2. Installation

Stork can be installed from pre-built packages or from sources; the following sections describe both methods. Unless there is a good reason to compile from sources, installing from native deb or RPM packages is easier and faster.

2.1. Compatible Systems

stork-server and stork-agent are written in the Go language; the server uses a PostgreSQL database. In principle, the software can be run on any POSIX system that has a Go compiler and PostgreSQL. It is likely the software can also be built on other modern systems, but ISC’s testing capabilities are modest. We encourage users to try running Stork on other OSes not on this list and report their findings to ISC.

We put the main effort into ensuring compatibility with live Ubuntu and RHEL long-time-support (LTS) versions.

The table below describes the checks performed on the particular operating systems.

Compatibility of the operating systems

System Family

System Version

Architecture

Unit Tests

System Tests

Build Binaries

Build Packages

Installation (without systemd)

Installation & Upgrade & Run (with systemd)

Debian

10

x64

X

Debian

11

x64

X

Debian

11

arm64

X

Debian

12

arm64

X

Debian

12.1-slim

x64

X

X

X

X

X

Debian

12.1-slim

arm64

X

X

X

Ubuntu

20.04

x64

X

Ubuntu

22.04

x64

D

D

D

D

X / D

Ubuntu

22.04

arm64

X

Ubuntu

24.04

x64

X

Ubuntu

24.04

arm64

X

RHEL

UBI 8.8

x64

X

X

X

RHEL

UBI 8.8

arm64

X

X

X

RHEL

8

x64

X

RHEL

9

x64

X

RHEL

9

arm64

X

Fedora

36

x64

X

Fedora

39

x64

X

Fedora

40

x64

X

Alpine

3.18

x64

X

X

X

Alpine

3.18

arm64

X

X

X

MacOS

14.4

arm64

D

D

D

D

D

FreeBSD

?

x64

U

U

U

U

OpenBSD

?

x64

U

U

U

Legend:

  • X - the check is regularly performed on our CI system

  • D - the operating system is used to develop Stork, so some checks are performed as a side effect

  • U - the check is not covered by our CI system, but some users reported successful passes

* MacOS is not and will not be officially supported. However, many developers on ISC’s team use Macs, so the intention is to keep Stork buildable on this platform.

** The BSD-like systems are not officially supported, but some users reported successful installations on these systems.

2.2. Installation Prerequisites

The Stork agent does not require any specific dependencies to run. It can be run immediately after installation.

Stork uses the status-get command to communicate with Kea.

Stork requires the premium Host Commands (host_cmds) hook library to be loaded by the Kea instance to retrieve host reservations stored in an external database. Stork works without the Host Commands hook library, but is not able to display host reservations. Stork can retrieve host reservations stored locally in the Kea configuration without any additional hook libraries.

Stork requires the open source Statistics Commands (stat_cmds) hook library to be loaded by the Kea instance to retrieve lease statistics. Stork works without the Stat Commands hook library, but is not able to show pool utilization and other statistics.

Stork uses Go implementation to handle TLS connections, certificates, and keys. The secrets are stored in the PostgreSQL database, in the secret table.

For the Stork server, a PostgreSQL database (https://www.postgresql.org/) version 10 or later is required. Stork will attempt to run with older versions, but may not work correctly. The general installation procedure for PostgreSQL is OS-specific and is not included here. However, please note that Stork uses pgcrypto extensions, which often come in a separate package. For example, a postgresql-crypto package is required on Fedora and postgresql12-contrib is needed on RHEL and CentOS.

2.3. Stork Tool

The Stork Tool is a program installed with the Stork Server, providing commands to set up server’s database and manage TLS certificates. Using this tool is facultative because the server runs the database migrations and creates suitable certificates at startup on its own. However, the tool provides useful commands for inspecting the current database schema version and downgrading to one of the previous versions. In addition, in the Preparing Stork Server Database section it is described how the tool can be conveniently used to create a new database and its credentials without a need to run SQL commands directly using the psql program.

The Inspecting Keys and Certificates section describes how to use the tool for TLS certificates management.

Further sections describe different methods for installing the Stork Server from packages. See: Installing on Debian/Ubuntu and Installing on CentOS/RHEL/Fedora. The stork-tool program is installed from the packages together with the server. Alternatively, the tool can be built from sources:

$ rake build:tool

Please refer to the manual page for usage details: stork-tool - A Tool for Managing Stork Server.

2.4. Preparing Stork Server Database

Before running Stork Server, a PostgreSQL database and the user with suitable privileges must be created. Using the stork-tool is the most convenient way to set up the database.

The following command creates a new database stork and a user stork with all privileges in this database. It also installs the pgcrypto extension required by the Stork Server.

$ stork-tool db-create --db-name stork --db-user stork
created database and user for the server with the following credentials  database_name=stork password=L82B+kJEOyhDoMnZf9qPAGyKjH5Qo/Xb user=stork

By default, stork-tool connects to the database as user postgres, a default admin role in many PostgreSQL installations. If an installation uses a different administrator name, it can be specified with the --db-maintenance-user option. For example:

$ stork-tool db-create --db-maintenance-user thomson --db-name stork --db-user stork
created database and user for the server with the following credentials  database_name=stork password=L82B+kJEOyhDoMnZf9qPAGyKjH5Qo/Xb user=stork

Similarly, a postgres database should often exist in a PostgreSQL installation. However, a different maintenance database can be selected with the --db-maintenance-name option.

The stork-tool generates a random password to the created database. This password needs to be copied into the server environment file or used in the stork-server command line to configure the server to use this password while connecting to the database. Use the --db-password option with the db-create command to create a user with a specified password.

It is also possible to create the database manually (i.e., using the psql tool).

First, connect to PostgreSQL using psql and the postgres administration user. Depending on the system’s configuration, it may require switching to the user postgres first, using the su postgres command.

$ psql postgres
psql (11.5)
Type "help" for help.
postgres=#

Then, prepare the database:

postgres=# CREATE USER stork WITH PASSWORD 'stork';
CREATE ROLE
postgres=# CREATE DATABASE stork;
CREATE DATABASE
postgres=# GRANT ALL PRIVILEGES ON DATABASE stork TO stork;
GRANT
postgres=# \c stork
You are now connected to database "stork" as user "postgres".
postgres=# GRANT ALL PRIVILEGES ON SCHEMA public TO stork;
GRANT
stork=# create extension pgcrypto;
CREATE EXTENSION

Note

Make sure the actual password is stronger than “stork”, which is trivial to guess. Using default passwords is a security risk. Stork puts no restrictions on the characters used in the database passwords, nor on their length. In particular, it accepts passwords containing spaces, quotes, double quotes, and other special characters. Please also consider using the stork-tool to generate a random password.

To generate a random password run:

$ stork-tool db-password-gen
generated new database password               password=1qWVzmLKy/j40/FVsvjM2ylcFdaFfNxh

The newly created database is not ready for use until necessary database migrations are executed. The migrations create tables, indexes, triggers, and functions required by the Stork Server. As mentioned above, the server can automatically run the migrations at startup, bringing up the database schema to the latest version. However, if a user wants to run the migrations before starting the server, they can use the stork-tool:

$ stork-tool db-init
$ stork-tool db-up

The up and down commands have an optional -t parameter that specifies the desired schema version. It is useful when debugging database migrations or downgrading to one of the earlier Stork versions.

$ # migrate up version 25
$ stork-tool db-up -t 25
$ # migrate down back to version 17
$ stork-tool db-down -t 17

The server requires the latest database version to run, always runs the migration on its own, and refuses to start if the migration fails for any reason. The migration tool is mostly useful for debugging problems with migration, or for migrating the database without actually running the service. For the complete manual page, please see stork-tool - A Tool for Managing Stork Server.

To debug migrations, another useful feature is SQL tracing using the --db-trace-queries parameter. The options are either “all” (trace all SQL operations, including migrations and runtime) or “run” (only trace runtime operations and skip migrations). If specified without any parameters, “all” is assumed. With it enabled, stork-tool prints out all its SQL queries on stderr. For example, these commands can be used to generate an SQL script that updates the schema. Note that for some migrations, the steps are dependent on the contents of the database, so this is not a universal Stork schema. This parameter is also supported by the Stork Server.

$ stork-tool db-down -t 0
$ stork-tool db-up --db-trace-queries 2> stork-schema.txt

2.4.1. Tuning Database Timeouts

In rare cases, reading or writing to the database may hang. This can be caused by a temporary network issue, or by misconfiguration of the proxy server switching the connection between different database instances. Setting appropriate timeout values can mitigate such issues.

PostgreSQL exposes two distinct connection options to configure the read and write timeouts. Stork’s corresponding configuration parameters specify the timeouts: --db-read-timeout (the STORK_DATABASE_READ_TIMEOUT environment variable) and --db-write-timeout (the STORK_DATABASE_WRITE_TIMEOUT). Non-zero timeout value must be specified with the unit, e.g., 500ms` for 500 milliseconds, 1s for one second, 5m for five minutes.

The default value is 0, which disables the timeout. In this case, Stork waits indefinitely for the completion of the read and write database operations.

Note

Some operations may take a long time to complete (e.g., pulling the hosts), especially when the monitored Kea configurations are large. The timeouts should be adjusted accordingly.

Warning

We don’t recommend specifying short timeouts when the database connection problems are rare and/or the hangs related to infinite reads or writes haven’t been observed. Specifying too short timeouts may lead to premature database reads or writes errors for long lasting operations.

Note that there are distinct flags --rest-read-timeout and --rest-write-timeout for controlling how long the REST API operation last. They are more suitable if you want to secure the Stork API against Denial-of-Service attacks that involve sending massive, long-processing requests to the web service to exhaust its resources.

2.5. Installing From Packages

Stork packages are stored in repositories located on the Cloudsmith service: https://cloudsmith.io/~isc/repos/stork/packages/. DEB (Debian/Ubuntu family), RPM (RedHat-family), and APK (Alpine) packages may be found there.

Detailed instructions for setting up the operating system to use this repository are available under the Set Me Up button on the Cloudsmith repository page.

A few command line tools are required for setting up the repository:

  • bash to execute the setup.*.sh scripts that use bash-specific features like == inside the test expression, local variables, function keyword in function declarations.

  • curl to fetch the setup.*.sh script itself, but also for actions carried out by the script like fetching GPG keys, checking if URLs are available, or fetching other scripts.

  • cut for the output manipulation done by the script

  • gpg for importing GPG keys in the script

  • sed for various textual substitutions done by the script

  • sudo for elevating privileges required by the package manager

  • apt-get in case of a Debian-based distribution

  • rpm in case of an RPM-based distribution

  • one of dnf, microdnf, yum, zypper in case of an RPM-based distribution

  • apk in case of an Alpine-based distribution

Other command line tools may be required based on how the script evolves or based on what OS the script is running on:

  • grep and head for filtering output

  • sort for sorting output

  • fmt and xargs for better reporting of errors

  • uname to detect the OS the script is running on

  • python and pip for a redundant way of automatically detecting the OS in case the main OS detection mechanism does not work

It is possible to install both stork-agent and stork-server on the same machine. It is useful in small deployments with a single monitored machine, to avoid setting up a dedicated system for the Stork server. In those cases, however, an operator must consider the potential impact of the stork-server on other services running on the same machine.

2.5.1. Installing the Stork Server

2.5.1.1. Installing on Debian/Ubuntu

The first step for both Debian and Ubuntu is:

$ curl -1sLf 'https://dl.cloudsmith.io/public/isc/stork/cfg/setup/bash.deb.sh' | sudo bash

Next, install the Stork server package:

$ sudo apt install isc-stork-server

2.5.1.2. Installing on CentOS/RHEL/Fedora

The first step for RPM-based distributions is:

$ curl -1sLf 'https://dl.cloudsmith.io/public/isc/stork/cfg/setup/bash.rpm.sh' | sudo bash

Next, install the Stork server package:

$ sudo dnf install isc-stork-server

If dnf is not available, yum can be used instead:

$ sudo yum install isc-stork-server

2.5.1.3. Installing on Alpine

The first step for Alpine is installing bash and curl:

$ apk add bash curl

Next, setup the Cloudsmith repository:

$ curl -1sLf 'https://dl.cloudsmith.io/public/isc/stork/cfg/setup/bash.apk.sh' | bash

Then, install the Stork server package:

$ apk add isc-stork-server

2.5.1.4. Setup

The following steps are common for Debian-based and RPM-based distributions using systemd.

Configure the Stork server settings in /etc/stork/server.env.

Note

The environment file IS NOT read by default if you run the Stork server manually (without using systemd). To load the environment variables from this file you should call the . /etc/stork/server.env command before executing the binary (in the same shell instance) or run Stork with the --use-env-file switch.

The following settings are required for the database connection (they have a common STORK_DATABASE_ prefix):

  • STORK_DATABASE_HOST - the address of a PostgreSQL database; the default is localhost

  • STORK_DATABASE_PORT - the port of a PostgreSQL database; the default is 5432

  • STORK_DATABASE_NAME - the name of a database; the default is stork

  • STORK_DATABASE_USER_NAME - the username for connecting to the database; the default is stork

  • STORK_DATABASE_PASSWORD - the password for the username connecting to the database

Note

All of the database connection settings have default values, but we strongly recommend protecting the database with a non-default and hard-to-guess password in the production environment. The STORK_DATABASE_PASSWORD setting must be adjusted accordingly.

The remaining settings pertain to the server’s RESTful API configuration (the STORK_REST_ prefix):

  • STORK_REST_HOST - the IP address on which the server listens

  • STORK_REST_PORT - the port number on which the server listens; the default is 8080

  • STORK_REST_TLS_CERTIFICATE - a file with a certificate to use for secure connections

  • STORK_REST_TLS_PRIVATE_KEY - a file with a private key to use for secure connections

  • STORK_REST_TLS_CA_CERTIFICATE - a certificate authority file used for mutual TLS authentication

    Providing the CA certificate path enables the TLS client certificate verification. Any HTTP request to the server assigned with a missing, invalid, or untrusted TLS certificate will be rejected.

  • STORK_REST_STATIC_FILES_DIR - a directory with static files served in the user interface

    The STORK_REST_STATIC_FILES_DIR should be set to /usr/share/stork/www for the Stork Server installed from the binary packages. It’s the default location for the static content.

  • STORK_REST_BASE_URL - the base URL of the UI

    Specify this flag if the UI is served from a subdirectory (not the root URL). It must start and end with a slash. Example: https://www.example.com/admin/stork/ would need to have “/admin/stork/” as the rest-base-url.

Note

The Stork agent must trust the REST TLS certificate presented by Stork server. Otherwise, the registration process fails due to invalid Stork Server certificate verification. We strongly recommend using proper, trusted certificates for security reasons. If you need to use a self-signed certificate (e.g., for deployment in the Docker environment), then you can add its CA certificate to the system certificates on the Stork agent machine. See Stack Overflow thread and discussion in #859.

The remaining settings pertain to the server’s Prometheus /metrics endpoint configuration (the STORK_SERVER_ prefix is for general purposes):

  • STORK_SERVER_ENABLE_METRICS - enable the Prometheus metrics collector and /metrics HTTP endpoint

Warning

The Prometheus /metrics endpoint does not require authentication. Therefore, securing this endpoint from external access is highly recommended to prevent unauthorized parties from gathering the server’s metrics. One way to restrict endpoint access is by using an appropriate HTTP proxy configuration to allow only local access or access from the Prometheus host. Please consult the NGINX example configuration file shipped with Stork.

With the settings in place, the Stork server service can now be enabled and started:

$ sudo systemctl enable isc-stork-server
$ sudo systemctl start isc-stork-server

To check the status:

$ sudo systemctl status isc-stork-server

Note

By default, the Stork server web service is exposed on port 8080 and can be tested using a web browser at http://localhost:8080. To use a different IP address or port, set the STORK_REST_HOST and STORK_REST_PORT variables in the /etc/stork/stork.env file.

The Stork server can be configured to run behind an HTTP reverse proxy using Nginx or Apache. The Stork server package contains an example configuration file for Nginx, in /usr/share/stork/examples/nginx-stork.conf.

The logging details, including colorization is configured analogously to the Stork Agent logging settings.

Stork can read and combine the configuration parameters from a few sources simultaneously. The command line flags have precedence over the environment variables read from the file when the –use-env-file flag is specified. The environment variables read from the file take precedence over the environment variables set in the current shell.

2.5.1.5. Stork UI Behind a Reverse Proxy

A reverse proxy is a server solution responsible for preliminary processing incoming requests from the Internet and redirecting them to specific web services running in the internal network. The reverse proxies may help increase performance (e.g., by caching responses), security (e.g., by enveloping the responses in TLS, logging the requests), and reliability (e.g., by allowing switching web service instances).

Stork is distributed with a basic configuration for Nginx. It is available, after installation from a package, in the dist/server/usr/share/stork/examples/nginx-stork.conf file. The same file is located in git repository: etc/nginx-stork.conf.

Stork Server can be configured to expose the web application from a URL subdirectory. It may be needed when there is no dedicated domain for Stork Server, and the web application is served from the subdirectory of an existing domain (e.g., http://example.com/stork).

If the backend executable (stork-server) and UI files (/usr/share/stork/www by default) are on the same machine, the backend is responsible for sharing the UI static files. You can configure the necessary subdirectory using the --rest-base-url CLI flag or the STORK_REST_BASE_URL environment variable. The value must be surrounded by slashes (e.g.: /stork/). The --rest-base-url CLI flag affects both the backend and UI. It changes the value of the <base> HTML tag in the index.html file (that modifies all links and URLs used by UI) and turns on the simple remapping of the requested URL (the backend trims the base path from processed URLs). The reverse proxy doesn’t require any special configuration.

If the backend and the UI files are located on different machines, you must manually modify the value of the <base> HTML tag in the index.html file. The href attribute must be set to a necessary subdirectory. The value must be surrounded by slashes (e.g.: /stork/). Configure your HTTP proxy server to rewrite the requested URL and remove the base URL before passing the requests to Stork Server. Below is an example of configuring the <VirtualHost> section for Apache. See the etc/httpd-stork.conf file for full configuration.

<VirtualHost *:81>
   <LocationMatch "^/stork">
      RewriteEngine On
      RewriteCond %{REQUEST_URI} ^/stork/(.*)
      RewriteRule ^ /%1 [L]
   </LocationMatch>

   # Other location rules here...

</VirtualHost>

2.5.1.6. Securing the Database Connection

The PostgreSQL server can be configured to encrypt communications between the clients and the server. Detailed information on how to enable encryption on the database server, and how to create the suitable certificate and key files, is available in the PostgreSQL documentation.

The Stork server supports secure communications with the database. The following configuration settings in the server.env file enable and configure communication encryption with the database server. They correspond with the SSL settings provided by libpq - the native PostgreSQL client library written in C:

  • STORK_DATABASE_SSLMODE - the SSL mode for connecting to the database (i.e., disable, require, verify-ca, or verify-full); the default is disable

  • STORK_DATABASE_SSLCERT - the location of the SSL certificate used by the server to connect to the database

  • STORK_DATABASE_SSLKEY - the location of the SSL key used by the server to connect to the database

  • STORK_DATABASE_SSLROOTCERT - the location of the root certificate file used to verify the database server’s certificate

The default SSL mode setting, disable, configures the server to use unencrypted communication with the database. Other settings have the following meanings:

  • require - use secure communication but do not verify the server’s identity unless the root certificate location is specified and that certificate exists. If the root certificate exists, the behavior is the same as in the case of verify-ca.

  • verify-ca - use secure communication and verify the server’s identity by checking it against the root certificate stored on the Stork server machine.

  • verify-full - use secure communication and verify the server’s identity against the root certificate. In addition, check that the server hostname matches the name stored in the certificate.

Specifying the SSL certificate and key location is optional. If they are not specified, the Stork server uses the ones from the current user’s home directory: ~/.postgresql/postgresql.crt and ~/.postgresql/postgresql.key. If they are not present, Stork tries to find suitable keys in common system locations.

Please consult the libpq documentation for similar libpq configuration details.

2.5.2. Installing the Stork Agent

There are two ways to install the packaged Stork agent on a monitored machine. The first method is to use the Cloudsmith repository, as with the Stork server installation. The second method, supported since Stork 0.15.0, is to use an installation script provided by the Stork server, which downloads the agent packages embedded in the server package. The preferred installation method depends on the selected agent registration type. Supported registration methods are described in Securing Connections Between the Stork Server and a Stork Agent.

2.5.2.1. Agent Configuration Settings

The following are the Stork agent configuration settings available in the /etc/stork/agent.env file after installing the package. All these settings use the STORK_AGENT_ prefix to indicate that they configure the Stork agent. Configuring Stork using the environment variables is recommended for deployments using systemd.

Note

The environment file IS NOT read by default if you run the Stork agent manually (without using systemd). To load the environment variables from this file you should call the . /etc/stork/agent.env command before executing the binary (in the same shell instance) or run Stork with the --use-env-file switch.

The general settings:

  • STORK_AGENT_HOST - the IP address of the network interface or DNS name which stork-agent should use to receive connections from the server; the default is 0.0.0.0 (i.e. listen on all interfaces)

  • STORK_AGENT_PORT - the port number the agent should use to receive connections from the server; the default is 8080

  • STORK_AGENT_LISTEN_STORK_ONLY - this enables Stork functionality only, i.e. disables Prometheus exporters; the default is false

  • STORK_AGENT_LISTEN_PROMETHEUS_ONLY - this enables the Prometheus exporters only, i.e. disables Stork functionality; the default is false

  • STORK_AGENT_SKIP_TLS_CERT_VERIFICATION - this skips TLS certificate verification when stork-agent connects to Kea over TLS and Kea uses self-signed certificates; the default is false

The following settings are specific to the Prometheus exporters:

  • STORK_AGENT_PROMETHEUS_KEA_EXPORTER_ADDRESS - the IP address or hostname the agent should use to receive the connections from Prometheus fetching Kea statistics; default is 0.0.0.0

  • STORK_AGENT_PROMETHEUS_KEA_EXPORTER_PORT - the port the agent should use to receive connections from Prometheus when fetching Kea statistics; the default is 9547

  • STORK_AGENT_PROMETHEUS_KEA_EXPORTER_INTERVAL - specifies how often the agent collects stats from Kea, in seconds; default is 10

  • STORK_AGENT_PROMETHEUS_KEA_EXPORTER_PER_SUBNET_STATS - enable or disable collecting per subnet stats from Kea; default is true (collecting enabled). You can use this option to limit the data passed to Prometheus/Grafana in large networks.

  • STORK_AGENT_PROMETHEUS_BIND9_EXPORTER_ADDRESS - the IP address or hostname the agent should use to receive the connections from Prometheus fetching BIND9 statistics; default is 0.0.0.0 to listen on for incoming Prometheus connection; default is 0.0.0.0

  • STORK_AGENT_PROMETHEUS_BIND9_EXPORTER_PORT - the port the agent should use to receive the connections from Prometheus fetching BIND9 statistics; default is 9119

  • STORK_AGENT_PROMETHEUS_BIND9_EXPORTER_INTERVAL - specifies how often the agent collects stats from BIND9, in seconds; default is 10

The last setting is used only when Stork agents register in the Stork server using an agent token:

  • STORK_AGENT_SERVER_URL - the stork-server URL used by the agent to send REST commands to the server during agent registration

Warning

stork-server does not currently support communication with stork-agent via an IPv6 link-local address with zone ID (e.g., fe80::%eth0). This means that the STORK_AGENT_HOST variable must be set to a DNS name, an IPv4 address, or a non-link-local IPv6 address.

Stork can read and combine the configuration parameters from a few sources simultaneously. The command line flags have precedence over the environment variables read from the file when the –use-env-file flag is specified. The environment variables read from the file take precedence over the environment variables set in the current shell.

2.5.2.2. Logging Settings

Unless otherwise specified using STORK_LOG_LEVEL, the default value of INFO log level is used. Supported log levels are: DEBUG, INFO, WARN, ERROR.

To control the logging colorization, Stork supports the CLICOLOR and CLICOLOR_FORCE standard UNIX environment variables. When set, the following rules will be applied:

  • CLICOLOR_FORCE != 0

    ANSI colors should be enabled no matter what.

  • CLICOLOR_FORCE == 0

    Don’t output ANSI color escape codes.

  • CLICOLOR_FORCE is unset and CLICOLOR == 0

    Don’t output ANSI color escape codes.

  • Otherwise

    ANSI colors are enabled if TTY is used.

For example, to disable the output colorization:

rake run:agent CLICOLOR=0

Note

The true and false values are also accepted instead of the 1 and 0.

2.5.2.3. Securing Connections Between the Stork Server and a Stork Agent

Connections between the server and the agents are secured using standard cryptography solutions, i.e. PKI and TLS.

The server generates the required keys and certificates during its first startup. They are used to establish safe, encrypted connections between the server and the agents with authentication at both ends of these connections. The agents use the keys and certificates generated by the server to create agent-side keys and certificates, during the agents’ registration procedure described in the next sections. The private key and CSR certificate generated by an agent and signed by the server are used for authentication and connection encryption.

An agent can be registered in the server using one of the two supported methods:

  1. using an agent token

  2. using a server token

In the first case, an agent generates a token and passes it to the server requesting registration. The server associates the token with the particular agent. A Stork super administrator must approve the registration request in the web UI, ensuring that the token displayed in the UI matches the agent’s token in the logs. The Stork agent is typically installed from the Cloudsmith repository when this registration method is used.

In the second registration method, a server generates a common token for all new registrations. The super admin must copy the token from the UI and paste it into the agent’s terminal during the interactive agent registration procedure. This registration method does not require any additional approval of the agent’s registration request in the web UI. If the pasted server token is correct, the agent should be authorized in the UI when the interactive registration completes. When this registration method is used, the Stork agent is typically installed using a script that downloads the agent packages embedded in the server.

The applicability of the two methods is described in Registration Methods Summary.

The installation and registration processes using each method are described in the subsequent sections.

2.5.2.4. Securing Connections Between stork-agent and the Kea Control Agent

The Kea Control Agent (CA) may be configured to accept connections only over TLS. It requires specifying trust-anchor, cert-file and key-file values in the kea-ctrl-agent.conf file. For details, see the Kea Administrator Reference Manual.

The Stork agent can communicate with Kea over TLS, via the same certificates that it uses in communication with the Stork server.

The Stork agent by default requires that the Kea Control Agent provide a trusted TLS certificate. If Kea uses a self-signed certificate, the Stork agent can be launched with the --skip-tls-cert-verification flag or STORK_AGENT_SKIP_TLS_CERT_VERIFICATION environment variable set to 1, to disable Kea certificate verification.

The Kea CA accepts only requests signed with a trusted certificate, when the cert-required parameter is set to true in the Kea CA configuration file. In this case, the Stork agent must use valid certificates; it cannot use self-signed certificates created during Stork agent registration.

Kea 1.9.0 added support for basic HTTP authentication to control access for incoming REST commands over HTTP. If the Kea CA is configured to use Basic Auth, valid credentials must be provided in the Stork agent credentials file: /etc/stork/agent-credentials.json.

By default, this file does not exist, but the /etc/stork/agent-credentials.json.template file provides example data. The template file can be renamed by removing the .template suffix; then the file can be edited and valid credentials can be provided. The chown and chmod commands should be used to set the proper permissions; this file contains the secrets, and should be readable/writable only by the user running the Stork agent and any administrators.

Warning

Basic HTTP authentication is weak on its own as there are known dictionary attacks, but those attacks require a “man in the middle” to get access to the HTTP traffic. That can be eliminated by using basic HTTP authentication exclusively over TLS. In fact, if possible, using client certificates for TLS is better than using basic HTTP authentication.

For example:

{
   "basic_auth": [
      {
         "ip": "127.0.0.1",
         "port": 8000,
         "user": "foo",
         "password": "bar"
      }
   ]
}

It contains a single object with a single “basic” key. The “basic” value is a list of the Basic Auth credentials. All credentials must contain the values for four keys:

  • ip - the IPv4 or IPv6 address of the Kea CA. It supports IPv6 abbreviations (e.g. “FF:0000::” is the same as “ff::”).

  • port - the Kea Control Agent port number.

  • user - the Basic Auth user ID to use in connection with a specific Kea CA.

  • password - the Basic Auth password to use in connection with a specific Kea CA.

To apply changes in the credentials file, the stork-agent daemon must be restarted.

If the credentials file is invalid, the Stork agent will run but without Basic Auth support. The notice will be indicated with a specific message in the log.

2.5.2.5. Installation From Cloudsmith and Registration With an Agent Token

This section describes how to install an agent from the Cloudsmith repository and perform the agent’s registration using an agent token.

The Stork agent installation steps are similar to the Stork server installation steps described in Installing on Debian/Ubuntu and Installing on CentOS/RHEL/Fedora. Use one of the following commands depending on the local Linux distribution:

$ sudo apt install isc-stork-agent

$ sudo dnf install isc-stork-agent

instead of the server installation commands.

Next, specify the required settings in the /etc/stork/agent.env file. The STORK_AGENT_SERVER_URL should be the URL on which the server receives the REST connections, e.g. http://stork-server.example.org:8080. The STORK_AGENT_HOST should point to the agent’s address (or name), e.g. stork-agent.example.org. Finally, a non-default agent port can be specified with the STORK_AGENT_PORT.

Note

Even though the examples provided in this documentation use the http scheme, we highly recommend using secure protocols in production environments. We use http in the examples because it usually makes it easier to start testing the software and eliminate all issues unrelated to the use of https before it is enabled.

Start the agent service:

$ sudo systemctl enable isc-stork-agent
$ sudo systemctl start isc-stork-agent

To check the status:

$ sudo systemctl status isc-stork-agent

The following log messages should be returned when the agent successfully sends the registration request to the server:

machine registered
stored agent signed cert and CA cert
registration completed successfully

A server administrator must approve the registration request via the web UI before a machine can be monitored. Visit the Services -> Machines page in the Stork UI, and click the Unauthorized button located above the list of machines on the right side. This list contains all machines pending registration approval. Before authorizing a machine, ensure that the agent token displayed on this list is the same as the agent token in the agent’s logs or the /var/lib/stork-agent/tokens/agent-token.txt file. If they match, click on the Action button and select Authorize. The machine should now be visible on the list of authorized machines.

2.5.2.6. Installation With a Script and Registration With a Server Token

This section describes how to install an agent using a script and packages downloaded from the Stork server and register the agent using a server token.

To enable this installation, you must download Stork agent packages from cloudsmith.io for the operating systems on which the agents will be installed. Next, put the downloaded packages in the assets/pkgs subdirectory of the directory holding Stork server’s static UI content. It is defined by the STORK_REST_STATIC_FILES_DIR environment variable, and its default location is /usr/share/stork/www. The supported package types are DEB, RPM, and APK. The package file names must start with the isc-stork-agent prefix and end with the .deb, .rpm, or .apk extensions. It is recommended to leave the original filenames.

Open Stork in the web browser and log in as a user from the “super admin” group. Select Services and then Machines from the menu. Click on the How to Install Agent on New Machine button to display the agent installation instructions. Copy and paste the commands from the displayed window into the terminal on the machine where the agent is installed. These commands are also provided here for convenience:

$ wget http://stork.example.org:8080/stork-install-agent.sh
$ chmod a+x stork-install-agent.sh
$ sudo ./stork-install-agent.sh

stork.example.org is an example URL for the Stork server; it must be replaced with the real server URL used in the deployment.

The script downloads an OS-specific agent package from the Stork server (deb or RPM), installs the package, and starts the agent’s registration procedure.

In the agent machine’s terminal, a prompt for a server token is presented:

>>>> Server access token (optional):

The server token is available for a super admin user after clicking on the How to Install Agent on New Machine button in the Services -> Machines page. Copy the server token from the dialog box and paste it in at the prompt displayed on the agent machine.

The following prompt appears next:

>>>> IP address or FQDN of the host with Stork Agent (the Stork Server will use it to connect to the Stork Agent):

Specify an IP address or fully qualified domain name (FQDN) that the server should use to reach out to an agent via the secure gRPC channel.

When asked for the port:

>>>> Port number that Stork Agent will use to listen on [8080]:

specify the port number for the gRPC connections, or hit Enter if the default port 8080 matches the local settings.

If the registration is successful, the following messages are displayed:

machine ping over TLS: OK
registration completed successfully

Unlike with Installation From Cloudsmith and Registration With an Agent Token, this registration method does not require approval via the web UI. The machine should already be listed among the authorized machines.

2.5.2.7. Installation With a Script and Registration With an Agent Token

This section describes how to install an agent using a script and packages downloaded from the Stork server and perform the agent’s registration using an agent token. It is an interactive alternative to the procedure described in Installation From Cloudsmith and Registration With an Agent Token.

Start the interactive registration procedure following the steps in the Installation With a Script and Registration With a Server Token section.

In the agent machine’s terminal, a prompt for a server token is presented:

>>>> Server access token (optional):

Because this registration method does not use the server token, do not type anything in this prompt. Hit Enter to move on.

The following prompt appears next:

>>>> IP address or FQDN of the host with Stork Agent (the Stork Server will use it to connect to the Stork Agent):

Specify an IP address or FQDN that the server should use to reach out to an agent via the secure gRPC channel.

When asked for the port:

>>>> Port number that Stork Agent will use to listen on [8080]:

specify the port number for the gRPC connections, or hit Enter if the default port 8080 matches the local settings.

The following log messages should be returned when the agent successfully sends the registration request to the server:

machine registered
stored agent signed cert and CA cert
registration completed successfully

As with Installation From Cloudsmith and Registration With an Agent Token, the agent’s registration request must be approved in the UI to start monitoring the newly registered machine.

2.5.2.8. Installation From Cloudsmith and Registration With a Server Token

This section describes how to install an agent from the Cloudsmith repository and perform the agent’s registration using a server token. It is an alternative to the procedure described in Installation With a Script and Registration With a Server Token.

The Stork agent installation steps are similar to the Stork server installation steps described in Installing on Debian/Ubuntu and Installing on CentOS/RHEL/Fedora. Use one of the following commands, depending on the Linux distribution:

$ sudo apt install isc-stork-agent

$ sudo dnf install isc-stork-agent

Start the agent service:

$ sudo systemctl enable isc-stork-agent
$ sudo systemctl start isc-stork-agent

To check the status:

$ sudo systemctl status isc-stork-agent

Start the interactive registration procedure with the following command:

$ su stork-agent -s /bin/sh -c 'stork-agent register -u http://stork.example.org:8080'

The last parameter should be the appropriate Stork server URL.

Follow the same registration steps described in Installation With a Script and Registration With a Server Token.

2.5.2.9. Registration Methods Summary

Stork supports two different agent-registration methods, described above. Both methods can be used interchangeably, and it is often a matter of preference which one the administrator selects. However, the agent token registration may be more suitable in some situations. This method requires a server URL, agent address (or name), and agent port as registration settings. If they are known upfront, it is possible to prepare a system (or container) image with the agent offline. After starting the image, the agent sends the registration request to the server and awaits authorization in the web UI.

The agent registration with the server token is always manual. It requires copying the token from the web UI, logging into the agent, and pasting the token. Therefore, the registration using the server token is not appropriate when it is impossible or awkward to access the machine’s terminal, e.g. in Docker. On the other hand, the registration using the server token is more straightforward because it does not require unauthorized agents’ approval via the web UI.

If the server token leaks, it poses a risk that rogue agents might register. In that case, the administrator should regenerate the token to prevent the uncontrolled registration of new agents. Regeneration of the token does not affect already-registered agents. The new token must be used for any new registrations.

The server token can be regenerated in the How to Install Agent on New Machine dialog box available after navigating to the Services -> Machines page.

2.5.2.10. Agent Setup Summary

After successful agent setup, the agent periodically tries to detect installed Kea DHCP or BIND9 services on the system. If it finds them, they are reported to the Stork server when it connects to the agent.

Further configuration and usage of the Stork server and the Stork agent are described in the Using Stork chapter.

2.5.2.11. Inspecting Keys and Certificates

The Stork server maintains TLS keys and certificates internally to secure the communication between stork-server and any agents. They can be inspected and exported using stork-tool, with a command such as:

$ stork-tool cert-export --db-url postgresql://user:pass@localhost/dbname -f srvcert -o srv-cert.pem

The above command may fail if the database password contains any characters requiring URL encoding. In this case, a command line with multiple switches can be used instead:

$ stork-tool cert-export --db-user user --db-password pass --db-host localhost --db-name dbname -f srvcert -o srv-cert.pem

The certificates and secret keys can be inspected using OpenSSL, using commands such as openssl x509 -noout -text -in srv-cert.pem (for the certificates) and openssl ec -noout -text -in cakey (for the keys).

There are five secrets that can be exported or imported: the Certificate Authority secret key (cakey), the Certificate Authority certificate (cacert), the Stork server private key (srvkey), the Stork server certificate (srvcert), and a server token (srvtkn).

For more details, please see stork-tool - A Tool for Managing Stork Server.

2.5.2.12. Using External Keys and Certificates

It is possible to use external TLS keys and certificates. They can be imported to the Stork server using stork-tool:

$ stork-tool cert-import --db-url postgresql://user:pass@localhost/dbname -f srvcert -i srv-cert.pem

The above command may fail if the database password contains any characters requiring URL encoding. In this case, a command line with multiple switches can be used instead:

$ stork-tool cert-import --db-user user --db-password pass --db-host localhost --db-name dbname -f srvcert -i srv-cert.pem

Both the Certificate Authority key and the Certificate Authority certificate must be changed at the same time, as the certificate depends on the key. If they are changed, then the server key and certificate must also be changed.

Note

Imported certificates and keys must follow the same standards as those self-generated by the Stork server. They must also have the same format. This ISC Knowledge Base article provides step-by-step examples of generating a new set of certificates using OpenSSL and importing them to Stork. Note that the example OpenSSL configurations from this article may have to be adjusted to the specifics of your deployment.

For more details, please see stork-tool - A Tool for Managing Stork Server.

2.5.3. Installing the hooks

The hook is an additional file (plugin) that extends the standard Stork functionalities. It contains functions that are called during handling of various operations and can change the typical flow or run in parallel. Independent developers may create the hooks and enhance the Stork applications with new, optional features.

The hook packages are distributed as RPM and DEB packages on Cloudsmith.

The hooks are binary files with the .so extension. These files must be placed in the hook directory. The default location is /usr/lib/stork-agent/hooks for Stork agent and /usr/lib/stork-server/hooks for Stork server. You can change it using the --hook-directory CLI option or setting the STORK_AGENT_HOOK_DIRECTORY or STORK_SERVER_HOOK_DIRECTORY environment variable.

All the hooks must be compatible with the used Stork application (agent or server) and its exact version. If the hook directory contains non-hook files or out-of-date hooks, then Stork will not run.

The hooks may provide own configuration options. The list of available options is listed in the output of the stork-agent --help and stork-server --help commands.

The list of supported Stork server hooks:

  • LDAP authentication

    The hook provides the possibility to authenticate users by LDAP credentials, fetch their profiles, and map LDAP groups into Stork roles.

2.5.4. Upgrading

Due to the new security model introduced with TLS in Stork 0.15.0, upgrades from versions 0.14.0 and earlier require the agents to be re-registered.

The server upgrade procedure is the same as the initial installation procedure.

Install the new packages on the server. Installation scripts in the deb/RPM package will perform the required database and other migrations.

2.6. Installing From Sources

2.6.1. Compilation Prerequisites

Usually, it is more convenient to install Stork using native packages. See Compatible Systems and Installing From Packages for details regarding supported systems. However, the sources can also be built separately.

The dependencies that need to be installed to build the Stork sources are:

  • Rake

  • Java Runtime Environment (only if building natively, not using Docker)

  • Docker (only if running in containers; this is needed to build the demo)

Other dependencies are installed automatically in a local directory by Rake tasks, which does not require root privileges. If the demo environment will be run, Docker is needed but not Java; Docker installs Java within a container.

For details about the environment, please see the Stork wiki at https://gitlab.isc.org/isc-projects/stork/-/wikis/Install .

2.6.2. Download Sources

The Stork sources are available in ISC’s GitLab instance: https://gitlab.isc.org/isc-projects/stork.

To get the latest sources invoke:

$ git clone https://gitlab.isc.org/isc-projects/stork

2.6.3. Building

There are two Stork components:

  • stork-agent - this is a binary, written in Go

  • stork-server - this is comprised of two parts: - backend service - a binary, written in Go - frontend - an Angular application written in Typescript

All components can be built using the following command:

$ rake build

The agent component is installed using this command:

$ rake install:agent

and the server component with this command:

$ rake install:server

By default, all components are installed in the specific system directories; this is useful for installation in a production environment. For the testing purposes tt can be customized via the DEST variable, e.g.:

$ rake install:server DEST=/home/user/stork

2.6.4. Installing on FreeBSD

Stork is not regularly tested on FreeBSD but can be installed on this operating system with the manual steps provided below.

The first step is the installation of packages from the repository:

pkg install ruby
pkg install rubygem-rake
pkg install wget
pkg install openjdk11-jre
pkg install node14
pkg install npm-node14
npm install -g npm
pkg install python3
pkg install protobuf
pkg install gcc
pkg install gtar

Stork build system can install all remaining dependencies automatically.

Unfortunately, there is no possibility to build the binary packages for OpenBSD. But it is possible to build the contents of the packages (executables, UI, man, and docs).

rake build:server_dist
rake build:agent_dist

The output files will be located in the dist/ directory.

2.6.5. Installing on OpenBSD

Stork is not regularly tested on OpenBSD but can be installed on this operating system with the manual steps provided below. The installation guide is similar to FreeBSD one.

The first step is the installation of packages from the repository:

pkg_add ruby
ln -s /usr/local/bin/gem31 /usr/local/bin/gem
gem install --user-install rake
pkg_add wget
pkg_add jdk
pkg_add node
pkg_add unzip
pkg_add protobuf
pkg_add gcc
pkg_add go

Stork requires Golang version 1.18 or later.

Stork build system can install all remaining dependencies automatically.

Unfortunately, there is no possibility to build the binary packages for OpenBSD. But it is possible to build the contents of the packages (executables, UI, man, and docs).

rake build:server_dist
rake build:agent_dist

The output files will be located in the dist/ directory.

2.6.6. Cross-compilation

Warning

Our tests do not cover the cross-compilation feature; you use it at your own risk.

The Stork build system fully supports Linux and MacOS operating systems on the AMD64 and ARM64 architectures. It is also prepared to handle FreeBSD and OpenBSD with some limitations but support for these systems isn’t actively maintained.

The Stork agent, server, and tool are written in pure Golang, which means they can be easily cross-compiled on all supported platforms.

You can use the rake utils:list_go_supported_platforms to get a list of all supported operating systems and architectures.

To build any Stork component for a specific platform, you need to provide the STORK_GOOS (for the operating system), STORK_GOARCH (for the architecture) and (optionally) STORK_GOARM (for ARM version, ARM architectures only) environment variables:

rake build:server STORK_GOOS=darwin STORK_GOARCH=arm64 STORK_GOARM=8
rake build:agent STORK_GOOS=freebsd STORK_GOARCH=amd64

These variables are supported for the build:server, build:agent, build:agent commands to compile the executable binaries. They can also be used with combination of the build:server_pkg and build:agent_pkg commands to build the packages:

rake build:server_pkg STORK_GOOS=darwin STORK_GOARCH=arm64
rake build:agent_pkg STORK_GOOS=freebsd STORK_GOARCH=amd64

Warning

Remember that the output package type always depends on the current operating system, not the executable type. It means that specifying the darwin operating system in STORK_GOOS and building the package on Debian causes generating a DEB package with a macOS-compatible executable, which is useless.

It is not recommended to compile Stork for 32-bit architectures as it may cause problems with unexpected integer overflows. Stork was never designed to operate on non-posix platforms, so Windows is not and will not be supported. Compiling Stork components for Windows is discouraged because Golang’s standard library may suppress some errors related to the file operations on the NTFS filesystem.

2.7. Integration With Prometheus and Grafana

Stork can optionally be integrated with Prometheus, an open source monitoring and alerting toolkit, and Grafana, an easy-to-view analytics platform for querying, visualization, and alerting. Grafana requires external data storage. Prometheus is currently the only environment supported by both Stork and Grafana. It is possible to use Prometheus without Grafana, but using Grafana requires Prometheus.

2.7.1. Prometheus Integration

The Stork agent, by default, makes Kea statistics, as well as some BIND 9 statistics, available in a format understandable by Prometheus. In Prometheus nomenclature, the Stork Agent works as a Prometheus “exporter.” If the Prometheus server is available, it can be configured to monitor Stork agents. To enable stork-agent monitoring, the prometheus.yml file (which is typically stored in /etc/prometheus/, but this may vary depending on the installation) must be edited to add the following entries:

# statistics from Kea
- job_name: 'kea'
  static_configs:
    - targets: ['agent-kea.example.org:9547', 'agent-kea6.example.org:9547', ... ]

# statistics from bind9
- job_name: 'bind9'
  static_configs:
    - targets: ['agent-bind9.example.org:9119', 'another-bind9.example.org:9119', ... ]

By default, the Stork agent exports Kea data on TCP port 9547 and BIND 9 data on TCP port 9119. This can be configured using command-line parameters, or the Prometheus export can be disabled altogether. For details, see the Stork agent manual page at stork-agent - Stork Agent to Monitor BIND 9 and Kea services.

The Stork server can also be optionally integrated, but Prometheus support for it is disabled by default. To enable it, run the server with the -m or --metrics flag or set the STORK_SERVER_ENABLE_METRICS environment variable. Next, update the prometheus.yml file:

# statistics from Stork Server
- job_name: 'storkserver'
   static_configs:
      - targets: ['server.example.org:8080']

The Stork server exports metrics on the assigned HTTP/HTTPS port (defined via the --rest-port flag).

Note

The Prometheus client periodically collects metrics from the clients (stork-server or stork-agent, for example), via an HTTP call. By convention, the endpoint that shares the metrics has the /metrics path. This endpoint returns data in Prometheus-specific format.

Warning

The Prometheus /metrics endpoint does not require authentication. Therefore, securing this endpoint from external access is highly recommended to prevent unauthorized parties from gathering the server’s metrics. One way to restrict endpoint access is by using an appropriate HTTP proxy configuration to allow only local access or access from the Prometheus host. Please consult the NGINX example configuration file shipped with Stork.

After restarting, the Prometheus web interface can be used to inspect whether the statistics have been exported properly. Kea statistics use the kea_ prefix (e.g. kea_dhcp4_addresses_assigned_total); BIND 9 statistics will eventually use the bind_ prefix (e.g. bind_incoming_queries_tcp); and Stork server statistics use the storkserver_ prefix.

2.7.2. Alerting in Prometheus

Prometheus provides the ability to configure alerting. A good starting point is the Prometheus documentation on alerting. Briefly, the three main steps are: configure the Alertmanager; configure Prometheus to talk to the Alertmanager; and define the alerting rules in Prometheus. There are no specific requirements or recommendations, as these are very deployment-dependent. The following is an incomplete list of ideas that could be considered:

  • The storkserver_auth_unreachable_machine_total metric is reported by stork-server and shows the number of unreachable machines. Its value under normal circumstances should be zero. Configuring an alert for non-zero values may be the best indicator of a large-scale problem, such as a whole VM or server becoming unavailable.

  • The storkserver_auth_authorized_machine_total and storkserver_auth_unauthorized_machine_total metrics may be used to monitor situations when new machines (e.g. by automated VM cloning) may appear in the network or existing machines may disappear.

  • The kea_dhcp4_addresses_assigned_total metric, along with kea_dhcp4_addresses_total, can be used to calculate pool utilization. If the server allocates all available addresses, it will not be able to handle new devices, which is one of the most common failure cases of the DHCPv4 server. Depending on the deployment specifics, a threshold alert when the pool utilization approaches 100% should be seriously considered.

  • Contrary to popular belief, DHCPv6 can also run out of resources, in particular with prefix delegation (PD). The kea_dhcp6_pd_assigned_total metric divided by kea_dhcp6_pd_total can be considered an indicator of PD pool utilization. It is an important metric if PD is being used.

The alerting mechanism configured in Prometheus has the relative advantage of not requiring an additional component (Grafana). The alerting rules are defined in a text file using simple YAML syntax. For details, see the Prometheus documentation on alerting rules. One potentially important feature is Prometheus’ ability to automatically discover available Alertmanager instances, which may be helpful in various redundancy considerations. The Alertmanager provides a rich list of receivers, which are the actual notification mechanisms used: email, PagerDuty, Pushover, Slack, Opsgenie, webhook, WeChat, and more.

ISC makes no specific recommendations between Prometheus or Grafana. This is a deployment consideration.

2.7.3. Grafana Integration

Stork provides several Grafana templates that can easily be imported, available in the grafana/ directory of the Stork source code. The currently available templates are bind9-resolver.json, kea-dhcp4.json, and kea-dhcp6.json. Grafana integration requires three steps:

1. Prometheus must be added as a data source. This can be done in several ways, including using the user interface to edit the Grafana configuration files. This is the easiest method; for details, see the Grafana documentation about Prometheus integration. Using the Grafana user interface, select Configuration, select Data Sources, click “Add data source,” and choose Prometheus; then specify the necessary parameters to connect to the Prometheus instance. In test environments, the only necessary parameter is the URL, but authentication is also desirable in most production deployments.

2. Import the existing dashboard. In the Grafana UI, click Dashboards, then Manage, then Import, and select one of the templates, e.g. kea-dhcp4.json. Make sure to select the Prometheus data source added in the previous step. Once imported, the dashboard can be tweaked as needed.

3. Once Grafana is configured, go to the Stork user interface, log in as “super admin”, click Settings in the Configuration menu, and then add the URLs for Grafana and Prometheus that point to the installations. Once this is done, Stork will be able to show links for subnets leading to specific subnets.

Alternatively, a Prometheus data source can be added by editing datasource.yaml (typically stored in /etc/grafana, but this may vary depending on the installation) and adding entries similar to this one:

datasources:
- name: Stork-Prometheus instance
  type: prometheus
  access: proxy
  url: http://prometheus.example.org:9090
  isDefault: true
  editable: false

The Grafana dashboard files can also be copied to /var/lib/grafana/dashboards/ (again, the exact location may vary depending on the installation).

Example dashboards with some live data can be seen in the Stork screenshots gallery .

2.7.4. Subnet Identification

The Kea Control Agent shares subnet statistics labeled with the internal Kea IDs. The Prometheus/Grafana subnet labels depend on the installed Kea hooks. By default, the internal, numeric Kea IDs are used. However, if the subnet_cmds hook is installed, then the numeric IDs are resolved to subnet prefixes. This makes the Grafana dashboard more human-friendly and descriptive.

2.7.5. Alerting in Grafana

Grafana offers multiple alerting mechanism options that can be used with Stork; users are encouraged to see the Grafana page on alerting.

The list of notification channels (i.e. the delivery mechanisms) is extensive, as it supports email, webhook, Prometheus’ Alertmanager, PagerDuty, Slack, Telegram, Discord, Google Hangouts, Kafka REST Proxy, Microsoft Teams, Opsgenie, Pushover, and more. Existing dashboards provided by Stork can be modified and new dashboards can be created. Grafana first requires a notification channel to be configured (Alerting -> Notifications Channel menu). Once configured, existing panels can be edited with alert rules. One caveat is that most panels in the Stork dashboards use template variables, which are not supported in alerting. This stackoverflow thread discusses several ways to overcome this limitation.

Compared to Prometheus alerting, Grafana alerting is a bit more user-friendly. The alerts are set using a web interface, with a flexible approach that allows custom notification messages, such as instructions on what to do when receiving an alert, information on how to treat situations where received data is null or there is a timeout, etc.

The defined alerts are considered an integral part of a dashboard. This may be a factor in a deployment configuration, e.g. the dashboard can be tweaked to specific needs and then deployed to multiple sites.