Dockerfile to build a Salt Project Master image for the Docker open source container platform. It's built with mysqlclient psycopg2 pre-installed for use in conjunction with databases

salt-master is installed inside the image using the Salt Project repositories for Ubuntu as documented in the official documentation.

For other methods to install salt-master, please refer to the Salt install guide.

Automated builds of the image are available on GitHub Container Registry and is the recommended method of installation.

docker pull ghcr.io/coralhl/salt-master:3006.8_1

You can also pull the latest tag, which is built from the repository HEAD

docker pull ghcr.io/coralhl/salt-master:latest

These images are also available from Docker Registry:

docker pull coralhl/salt-master:latest

Alternatively, you can build the image locally using make command:

make release

The quickest way to get started is using docker compose.

wget https://raw.githubusercontent.com/coralhl/salt-master-docker/master/docker-compose.yml

Start the salt-master container with the docker-compose.yml file by executing:

docker compose up --detach

Alternatively, you can manually launch the salt-master container:

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env 'SALT_LOG_LEVEL=info' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    ghcr.io/coralhl/salt-master:latest

This image uses its own master.yml file to configure salt-master to run properly inside the container. However, you can still tune other configuration parameters to fit your needs by adding your configuration files inside a config/ directory and mounting it into /home/salt/data/config/.

For example, you can customize the Reactor System by adding a reactor.conf file to config/:

# config/reactor.conf
reactor:                                          # Master config section "reactor"
  - 'salt/minion/*/start':                        # Match tag "salt/minion/*/start"
    - /home/salt/data/config/reactor/start.sls    # Things to do when a minion starts

Then, you have to add the start.sls file into your config/reactor/ directory:

# config/reactor/start.sls
highstate_run:
  local.state.apply:
    - tgt: {{ data['id'] }}

Finally, run your salt-master instance mounting the required directories:

docker run --name salt-master -d \
    --publish 4505:4505 --publish 4506:4506 \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/config/:/home/salt/data/config/ \
    ghcr.io/coralhl/salt-master:latest

This image provides support for automatically restart salt-master when configuration files change. This support is disabled by default, but it can be enabled by setting the SALT_RESTART_MASTER_ON_CONFIG_CHANGE environment variable to True.

In order to provide salt with your custom states, you must bind the volume /home/salt/data/srv/ to your roots directory.

Minion keys can be added automatically on startup to salt-master by mounting the volume /home/salt/data/keys and copying the minion keys inside keys/minions/ directory.

Note: The directory /home/salt/data/keys is defined as a volume in the salt-master image, so its contents can persist after the container is removed. However, it is recommended to mount this directory to a named volume or a host directory. That way, you can manage your keys outside the container and avoid losing them when the container is removed.

mkdir -p keys/minions
rsync root@minion1:/etc/salt/pki/minion/minion.pub keys/minions/minion1

docker run --name salt-master -d \
    --publish 4505:4505 --publish 4506:4506 \
    --env 'SALT_LOG_LEVEL=info' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/config/:/home/salt/data/config/ \
    ghcr.io/coralhl/salt-master:latest

Also, you can set your salt-master instance to auto accept minions that match certain grains. To do that, add the autosign_grains.conf to your config directory:

# config/autosign_grains.conf
autosign_grains_dir: /home/salt/data/srv/autosign_grains

Then, inside roots/autosign_grains you can place a file named like the grain you want to match and fill it with the content to match. For example, if you want to auto accept minions that belong to specific domains, you have to add the domain file with the domains you want to allow:

# roots/autosign_grains/domain
coralhl.io
coralhl.com

It is possible that you have to configure the minion to send the specific grains to the master in the minion config file:

# minion: /etc/salt/minion.d/autosign_grains.conf
autosign_grains:
  - domain

More info at: Salt Project - Auto accept Minions From Grains

It is possible to use signed master keys by establishing the environment variable SALT_MASTER_SIGN_PUBKEY to True.

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env 'SALT_LOG_LEVEL=info' \
    --env 'SALT_MASTER_SIGN_PUBKEY=True' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    ghcr.io/coralhl/salt-master:latest

The container will create the master_sign key and its signature. More information about how to configure the minion service can be found here .

Additionally, you can generate new signed keys for your existing master key by executing the following command:

docker run --name salt-master -it --rm \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    ghcr.io/coralhl/salt-master:latest \
    app:gen-signed-keys

The newly created keys will appear inside keys/generated/master_sign.XXXXX directory. Where XXXXX is a random code to avoid possible collisions with previous generated keys.

Master keys can be provided via Docker secrets. To do that, you have to set the following environment variable:

• SALT_MASTER_KEY_FILE: The path to the master-key-pair {pem,pub} files without suffixes.

Additionally, you can provide the master-sign key pair as well:

• SALT_MASTER_SIGN_KEY_FILE: The path to the master-sign-key-pair {pem,pub} files without suffixes.
• SALT_MASTER_PUBKEY_SIGNATURE_FILE: The path of the salt-master public key file with the pre-calculated signature.

Here you have a complete docker-compose.yml example

version: "3.9"

services:
  salt-master:
    image: ghcr.io/coralhl/salt-master:latest
    ports:
      - "4505:4505"
      - "4506:4506"
    volumes:
      - ./config:/home/salt/data/config
    secrets:
      - source: salt-master-key
        target: master.pem
        uid: 1000 # Or $PUID if env variable established
        gid: 1000 # Or $GUID if env variable established
        mode: 0400
      - source: salt-master-pub
        target: master.pub
        uid: 1000 # Or $PUID if env variable established
        gid: 1000 # Or $GUID if env variable established
        mode: 0644
      - source: salt-master-sign-priv-key
        target: master_sign.pem
        uid: 1000 # Or $PUID if env variable established
        gid: 1000 # Or $GUID if env variable established
        mode: 0400
      - source: salt-master-sign-pub-key
        target: master_sign.pub
        uid: 1000 # Or $PUID if env variable established
        gid: 1000 # Or $GUID if env variable established
        mode: 0644
      - source: salt-master-signature
        target: master_pubkey_signature
        uid: 1000 # Or $PUID if env variable established
        gid: 1000 # Or $GUID if env variable established
        mode: 0644
    environment:
      SALT_MASTER_SIGN_PUBKEY: True
      SALT_MASTER_KEY_FILE: /run/secrets/master
      SALT_MASTER_SIGN_KEY_FILE: /run/secrets/master_sign
      SALT_MASTER_PUBKEY_SIGNATURE_FILE: /run/secrets/master_pubkey_signature

secrets:
  salt-master-pem-key:
    file: keys/master.pem
  salt-master-pub-key:
    file: keys/master.pub
  salt-master-sign-priv-key:
    file: keys/master_sign.pem
  salt-master-sign-pub-key:
    file: keys/master_sign.pub
  salt-master-signature:
    file: keys/master_pubkey_signature

You can enable salt-api service by setting env variable SALT_API_ENABLED to True.

A self-signed SSL certificate will be automatically generated and the following configuration will be added to the master configuration file:

rest_cherrypy:
  port: 8000
  ssl_crt: /etc/pki/tls/certs/salt-master.crt
  ssl_key: /etc/pki/tls/certs/salt-master.key

The container exposes port 8000 by default, although you can map this port to whatever port you like in your docker run command:

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 --publish 8000:8000 \
    --env 'SALT_API_ENABLED=True' \
    --env 'SALT_API_USER_PASS=4wesome-Pass0rd' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/config/:/home/salt/data/config/ \
    ghcr.io/coralhl/salt-master:latest

If you choose using the docker-compose.yml file to manage your salt-master instance, uncomment salt-api settings to enable and configure the service.

By default, user salt_api is created, and you can set its password by setting the environment variable SALT_API_USER_PASS.

You can also change the salt-api username by setting SALT_API_USER. It is possible to disable this user by explicitly setting this variable to an empty string: SALT_API_USER='' if you are going to use an LDAP server.

As a security measure, if SALT_API_ENABLED is set to True and you don't disable SALT_API_USER, you'll be required to set SALT_API_USER_PASS. Otherwise, the setup process will fail and your container won't work.

SALT_API_USER_PASS_FILE env variable is available to provide the password via a file. This is useful when using Docker secretes. More info about how to configure secrets can be found in the subsection Working with secrets.

With all that set, you'll be able to provide your salt-api custom configuration by creating the salt-api.conf file inside your conf directory:

external_auth:
  pam:
    salt_api:
      - .*
      - "@runner"
      - "@wheel"
      - "@jobs"

More information is available in the following link: External Authentication System (eAuth).

Now you have your salt-master Docker image ready to accept external authentications and to connect external tools such as saltstack/pepper.

The pepper CLI script allows users to execute Salt commands from computers that are external to computers running the salt-master or salt-minion daemons as though they were running Salt locally.

pip3 install salt-pepper

Then configure pepper by filling your ~/.pepperrc file with your salt-api credentials:

[main]
SALTAPI_URL=https://your.salt-master.hostname:8000/
SALTAPI_USER=salt_api
SALTAPI_PASS=4wesome-Pass0rd
SALTAPI_EAUTH=pam

Begin executing salt states with pepper:

pepper '*' test.ping

This image contains support for running a built-in salt-minion service. You can enable it by setting the environment variable SALT_MINION_ENABLED to True.

The salt-minion will be automatically accepted by the master. Keys will be automatically configured, even if SALT_MASTER_SIGN_PUBKEY=True.

However, minion keys can be provided via Docker secrets. To do that, you have to set the env variable SALT_MINION_KEY_FILE, pointing to the path inside the container of the minion-key-pair {pem,pub} files without extensions.

Minion's keys will be stored inside the keys/SALT_MINION_ID/ directory.

This minion can be configured in the same way as the master. You can add your custom configuration files inside a minion_config/ directory and mount it into /home/salt/data/minion_config/.

The default id of the minion is builtin.minion. But you can change it by setting the environment variable SALT_MINION_ID.

Log levels are the same as the master, and you can set them by using the SALT_LOG_LEVEL and SALT_LEVEL_LOGFILE environment variables.

Here you have an example of how to run a salt-master with a built-in salt-minion:

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env 'SALT_MINION_ENABLED=True' \
    --env 'SALT_MINION_ID=control-minion' \
    --env 'SALT_MASTER_SIGN_PUBKEY=True' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/config/:/home/salt/data/config/ \
    --volume $(pwd)/minion_config/:/home/salt/data/minion_config/ \
    ghcr.io/coralhl/salt-master:latest

By default, the container is configured to run salt-master as user and group salt with uid and gid 1000. From the host the mounted data volumes will be shown as owned by user:group 1000:1000. This can be a problem if the host's id is different from 1000 or if files have too restrictive permissions. Specially the keys directory and its contents.

Also, the container processes seem to be executed as the host's user/group 1000. To avoid this, the container can be configured to map the uid and gid to match host ids by passing the environment variables PUID and PGID. The following command maps the ids to the current user and group on the host.

docker run --name salt-master -it --rm \
    --publish 4505:4505 --publish 4506:4506 \
    --env "PUID=$(id -u)" --env "PGID=$(id -g)" \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    ghcr.io/coralhl/salt-master:latest

This image uses PyGit2 as gitfs backend to allow Salt to serve files from git repositories.

It can be enabled by adding gitfs to the fileserver_backend list (see Available Configuration Parameters), and configuring one or more repositories in gitfs_remotes.

You can create an ssh key for pygit2 with the following command:

ssh-keygen -t ed25519 -C  -f gitfs_ssh -C '[email protected]'

Place it wherever you want inside the container and specify its path with the configuration parameters: gitfs_pubkey and gitfs_privkey in your gitfs.conf file.

For example:

# config/gitfs.conf
gitfs_provider: pygit2
gitfs_privkey: /home/salt/data/keys/gitfs/gitfs_ssh
gitfs_pubkey: /home/salt/data/keys/gitfs/gitfs_ssh.pub

This image has been tested with an ed25519 ssh key.

Alternately, you may create a new RSA key with SHA2 hashing like so:

ssh-keygen -t rsa-sha2-512 -b 4096 -f gitfs_ssh -C '[email protected]'

Salt can use GPG keys to decrypt pillar data. This image is ready to import your GPG keys from the gpgkeys directory inside the keys directory.

The private key must be named private.key and the public key pubkey.gpg.

If you want to provide these keys via secrets, you can set SALT_GPG_PRIVATE_KEY_FILE and SALT_GPG_PUBLIC_KEY_FILE env variables to specify the path to the files inside the container.

For example:

# docker-compose.yml
services:
  salt-master:
    ...
    env:
      SALT_GPG_PRIVATE_KEY_FILE: /run/secrets/private.key
      SALT_GPG_PUBLIC_KEY_FILE: /run/secrets/pubkey.gpg

In this case, keys will be symlinked to the gpgkeys directory.

It is important that the private key doesn't have passphrase in order to be imported by salt.

To generate a GPG key and export the private/public pair you can use the following commands:

# Generate key - REMEMBER: Leave empty the passphrase!
gpg --gen-key

# Check GPG keys
gpg --list-secret-keys
gpg: checking the trustdb
gpg: marginals needed: 3  completes needed: 1  trust model: pgp
gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: next trustdb check due at 2024-11-09
/tmp/gpgkeys/pubring.kbx
--------------------
sec   rsa3072 2022-11-10 [SC] [expires: 2024-11-09]
      CB032BA54F21722945FDDE399CE3DB8AE37D28B7
uid           [ultimate] Carlos Alvaro <[email protected]>
ssb   rsa3072 2022-11-10 [E] [expires: 2024-11-09]

# Export public and private keys
mkdir -p keys/gpgkeys
[email protected]
gpg --armor --export "${KEY_ID}" > keys/gpgkeys/pubkey.gpg
gpg --export-secret-keys --export-options export-backup -o keys/gpgkeys/private.key "${KEY_ID}"

More information about this feature is available at the official documentation.

You can encrypt strings using the following example:

echo -n 'Super secret pillar' | gpg --armor --batch --trust-model always --encrypt --recipient "${KEY_ID}"

Or you can encrypt files using the example bellow:

gpg --armor --batch --trust-model always --encrypt --recipient "${KEY_ID}" \
  --output /tmp/gpg_id_ed25519 ~/.ssh/id_ed25519
cat /tmp/gpg_id_ed25519

On macOS, you can pipe the output to pbcopy to copy the encrypted data to the clipboard. If you are using Linux, you can use xclip or xsel.

You can add third party formulas to your configuration simply by adding them to your gitfs_remotes:

# fileserver.conf
fileserver_backend:
  - roots
  - gitfs

# gitfs.conf
gitfs_provider: pygit2
gitfs_remotes:
  - https://github.com/saltstack-formulas/apache-formula
  - https://github.com/aokiji/salt-formula-helm.git

This is the Salt recommended way of doing it, and you can go to the Git Fileserver section on this document if you need help configuring the service.

You can find a great set of formulas on the following GitHub repositories:

• Official Salt Formulas
• Unofficial Salt Formulas

Although, as mention in Salt Project documentation , you are encouraged to fork desired formulas to avoid unexpected changes to your infrastructure.

However, sometimes you may need to load some formulas that are not available on a git repository, and you want to have them separated from your main srv directory.

For that case, you can mount a volume containing all your third party formulas separated in subdirectories into /home/salt/data/3pfs/, and they will be automatically added to the master configuration when your container starts.

# 3pfs directory content
3pfs
├── custom-formula
├── golang-formula
└── vim-formula

docker run --name salt-master -it --rm \
    --publish 4505:4505 --publish 4506:4506 \
    --env "PUID=$(id -u)" --env "PGID=$(id -g)" \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/3pfs/:/home/salt/data/3pfs/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    ghcr.io/coralhl/salt-master:latest

If you need to add more third party formulas, you can restart the container, or you can type the following command:

docker exec -it salt-master /sbin/entrypoint.sh app:reload-3rd-formulas

file_roots base configuration file will be updated with current existing formulas and salt-master service will be restarted to reload the new configuration.

Some formulas may depend on Python packages that are not included in the default Salt installation. You can add these packages by setting the PYTHON_PACKAGES_FILE environment variable with an absolute path pointing to a requirements.txt file inside the container.

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env SALT_LOG_LEVEL="info" \
    --env PYTHON_PACKAGES_FILE=/home/salt/data/other/requirements.txt \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/logs/:/home/salt/data/logs/ \
    --volume $(pwd)/requirements.txt:/home/salt/data/other/requirements.txt \
    ghcr.io/coralhl/salt-master:latest

This will install the packages listed in the requirements.txt file into the container before salt-master starts.

Alternatively, you can set the PYTHON_PACKAGES environment variable with a list of Python packages to be installed.

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env SALT_LOG_LEVEL="info" \
    --env PYTHON_PACKAGES="docker==7.0.0 redis" \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/logs/:/home/salt/data/logs/ \
    ghcr.io/coralhl/salt-master:latest

Although both methods are supported, they are mutually exclusive. If both are set, PYTHON_PACKAGES_FILE will take precedence.

salt-master output is streamed directly to the container's stdout and stderr. However, they are also written inside /home/salt/data/logs/.

This directory is defined as a volume so logs can persist after the container is removed.

Inside the directory you could find supervisor/ logs and salt/ logs.

You can access all logs by mounting the volume: /home/salt/data/logs/.

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --env 'SALT_LOG_LEVEL=info' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/logs/:/home/salt/data/logs/ \
    ghcr.io/coralhl/salt-master:latest

Check Available Configuration Parameters section for configuring logrotate.

This image includes a health check script: /usr/local/sbin/healthcheck (although it is disabled by default). It is useful to check if the salt-master service is alive and responding.

If you are running this image under k8s, you can define a liveness command as explained here .

If you use docker-compose as your container orchestrator, you can add the following entries to your compose file:

version: "3.4"

services:
  master:
    container_name: salt-master
    image: ghcr.io/coralhl/salt-master:latest
    healthcheck:
      test: ["CMD", "/usr/local/sbin/healthcheck"]
      start_period: 30s

(More info available at compose file official documentation)

Or, if you launch your container with docker:

docker run --name salt-master --detach \
    --publish 4505:4505 --publish 4506:4506 \
    --health-cmd='/usr/local/sbin/healthcheck' \
    --health-start-period=30s \
    --env 'SALT_LOG_LEVEL=info' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/logs/:/home/salt/data/logs/ \
    ghcr.io/coralhl/salt-master:latest

Then you can manually check this info by running the following command:

docker inspect --format "{{json .State.Health }}" salt-master | jq

Then, the output will be something similar to this:

{
  "Status": "healthy",
  "FailingStreak": 0,
  "Log": [
    {
      "Start": "2020-05-23T16:47:55.1046568Z",
      "End": "2020-05-23T16:48:02.3381442Z",
      "ExitCode": 0,
      "Output": "local:\n    True\n"
    }
  ]
}

If you run your salt-master instance with healthcheck enabled, you can use willfarrell/autoheal image to restart your service when healthcheck fails:

docker run -d \
  --name autoheal \
  --restart=always \
  -e AUTOHEAL_CONTAINER_LABEL=all \
  -v /var/run/docker.sock:/var/run/docker.sock \
  willfarrell/autoheal

This container will watch your containers and restart your failing instances.

Please refer the docker run command options for the --env-file flag where you can specify all required environment variables in a single file. This will save you from writing a potentially long docker run command. Alternatively you can use docker-compose.

Below you can find a list with the available options that can be used to customize your salt-master installation.

Any parameter not listed in the above table and available in the following link, can be set by creating the directory config and adding into it a .conf file with the desired parameters:

mkdir config
cat > config/ports.conf << EOF
# The tcp port used by the publisher:
publish_port: 3505
# The port used by the communication interface.
ret_port: 3506
EOF

docker run --name salt-master -d \
    --publish 3505:3505 --publish 3506:3506 \
    --env 'SALT_LOG_LEVEL=info' \
    --volume $(pwd)/roots/:/home/salt/data/srv/ \
    --volume $(pwd)/keys/:/home/salt/data/keys/ \
    --volume $(pwd)/config/:/home/salt/data/config/ \
    ghcr.io/coralhl/salt-master:latest

To test which salt minions are listening the following command can be executed directly from the host machine:

docker exec -it salt-master salt '*' test.ping

Then, you can apply salt states to your minions:

docker exec -it salt-master salt '*' state.apply [state]

For debugging and maintenance purposes you may want to access the container's shell. If you are using docker version 1.3.0 or higher you can access a running container shell using docker exec command.

docker exec -it salt-master bash

You can restart containers services by running the following command:

docker exec -it salt-master entrypoint.sh app:restart [salt-service]

Where salt-service is one of: salt-master or salt-api (if SALT_API_ENABLED is set to True).

Everyone is wellcome to contribute to this project, and I really appreciate your support. So don't be shy!

Before you start making changes, read carefully the following notes in order to avoid issues.

• ⚠️ Some tests start and stop a non-isolated salt-minion instance. So don't run tests locally. Tests are automatically executed on GitHub when you push commits to your PR.

Many thanks to:

• The SaltProject team for the excellent salt project
• JetBrains for their free OpenSource license
• The Contributors for all the smart code and suggestions merged in the project
• The Stargazers for showing their support

• https://docs.saltproject.io/en/getstarted/
• https://docs.saltproject.io/en/latest/contents.html

This project is available as open source under the terms of the MIT License.