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Quickstart Guide


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Overview

A Docker swarm service for automatically updating your services whenever their base image is refreshed.
This Wiki Post will guide you through setting up Shepherd for Docker Swarm.

Prerequisite

Having a running Docker Swarm Enviroment (https://wiki.aeoneros.com/books/docker-guide/chapter/swarm-mode)

Usage

Docker CLI

docker service create --name shepherd \
  --constraint "node.role==manager" \
  --mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock,ro \
  containrrr/shepherd

Docker Compose

version: "3"
services:
  shepherd:
    image: containrrr/shepherd
    environment:
      TZ: 'US/Eastern'
      SLEEP_TIME: '5m'
      FILTER_SERVICES: ''
      VERBOSE: 'true'
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    deploy:
      placement:
        constraints:
          - node.role == manager

Compose Examples:

docker-compose.apprise.yml 
version: "3"

services:
  app:
    image: containrrr/shepherd
    environment:
      APPRISE_SIDECAR_URL: notify:5000
      TZ: 'US/Eastern'
      SLEEP_TIME: '5m'
      FILTER_SERVICES: ''
      VERBOSE: 'true'
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    networks:
      - notification
    deploy:
      placement:
        constraints:
          - node.role == manager

  notify:
    image: mazzolino/apprise-microservice:0.1
    environment:
      NOTIFICATION_URLS: mailtos://user:pass@domain/?to=target@example.com
    networks:
      - notification

networks:
  notification:

 

docker-compose.labels.yml 
version: "3"

services:
  shepherd:
    image: containrrr/shepherd
    environment:
      # Beware YAML gotchas regarding quoting:
      # With KEY: 'VALUE', quotes are part of yaml syntax and thus get stripped
      # but with KEY='VALUE', they are part of the value and stay there,
      # causing problems!
      SLEEP_TIME: "1d"
      TZ: "US/Eastern"
      VERBOSE: "true"
      IGNORELIST_SERVICES: "label=shepherd.autodeploy=false"
      FILTER_SERVICES: "label=shepherd.autodeploy=true"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    deploy:
      placement:
        constraints:
          - node.role == manager

  # Explicitly enable shepherd for this service
  updating-app:
    image: hello-world
    deploy:
      labels:
        - shepherd.autodeploy=true

  # Explicitly disable shepherd for this service
  not-updating-app:
    image: hello-world
    deploy:
      labels:
        - shepherd.autodeploy=false

  # Implicitly disable shepherd for this service
  # because of FILTER_SERVICES above
  another-not-updating-app:
    image: hello-world

 

docker-compose.swarm-cronjob.yml 
version: "3"

services:
  app:
    image: containrrr/shepherd
    environment:
      TZ: 'US/Eastern'
      FILTER_SERVICES: ''
      IGNORELIST_SERVICES: "test"
      RUN_ONCE_AND_EXIT: "true"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    deploy:
      replicas: 0
      restart_policy:
        condition: none
      labels:
        - swarm.cronjob.enable=true
        # Start service every day at midnight
        - swarm.cronjob.schedule=0 0 0 * * *
        - swarm.cronjob.skip-running=true
      placement:
        constraints:
          - node.role == manager

  scheduler:
    image: crazymax/swarm-cronjob:latest
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    environment:
      - "TZ=Europe/Berlin"
      - "LOG_LEVEL=info"
      - "LOG_JSON=false"
    deploy:
      placement:
        constraints:
          - node.role == manager

 

How does it work?

Shepherd triggers updates by updating the image specification for each service, removing the current digest. Docker resolves the image tag, checks the registry for a newer version, and updates running container tasks as needed. Docker handles rolling updates, minimizing downtime for replicated services.

Configuration / Environment Variables

Below is a table of environment variables used for configuring Shepherd:

Environment Variable Description Example Value
SLEEP_TIME Time interval between update checks (default: 5 minutes) 5m
IGNORELIST_SERVICES Space-separated list of services to ignore during updates shepherd my-other-service
FILTER_SERVICES Filter for specifying services to update (matches docker service ls filter) label=com.mydomain.autodeploy
ROLLBACK_ON_FAILURE Roll back a service to the previous version if an update fails true
UPDATE_OPTIONS Additional options for the docker service update command --update-delay=30s
TIMEOUT Timeout for the docker service update process (default: 5 minutes) 300
APPRISE_SIDECAR_URL URL for the Apprise sidecar service to enable update notifications apprise-microservice:5000
IMAGE_AUTOCLEAN_LIMIT Enable old image autocleaning on service update 5
RUN_ONCE_AND_EXIT Run Shepherd once and then exit true
WITH_REGISTRY_AUTH Enable private registry authentication true
REGISTRY_USER / REGISTRY_PASSWORD Credentials for private registry authentication user123 / secret_password
REGISTRIES_FILE Path to the secret file containing multiple registry authentication entries /var/run/secrets/shepherd-registries-auth
WITH_INSECURE_REGISTRY Enable connection to an insecure private registry true
WITH_NO_RESOLVE_IMAGE Prevent pulling images from the registry true
TZ Set the timezone for log entries Europe/Zurich

Use Private Registry Authentication

Use Private Registry Authentication

Use Private Registry Authentication

You can enable private registry authentication by setting the WITH_REGISTRY_AUTH variable. Use REGISTRY_USER and REGISTRY_PASSWORD for a single registry. If using multiple accounts, create a secret file with the following format:

idregistryloginpassword

Example:

blog    registry.gitlab.com    gitlab+deploy-token-5123674    ssw2Nrd2

Create the Docker secret:

docker secret create shepherd-registries-auth private/shepherd-registries-auth

Then use the secret in your docker-compose.yml:

services:
  app:
    image: containrrr/shepherd
    environment:
      REGISTRIES_FILE: /var/run/secrets/shepherd-registries-auth
    secrets:
      - shepherd-registries-auth
secrets:
  shepherd-registries-auth:
    external: true

Add a label to specify the correct line from the secret file:

deploy:
  labels:
    - shepherd.enable=true
    - shepherd.auth.config=blog

Set WITH_INSECURE_REGISTRY to true to connect to an insecure private registry.

Set WITH_NO_RESOLVE_IMAGE to true to prevent pulling images from the

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