Docker wait for dependencies

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Container to wait for container healthchecks before proceeding with the stack start
Available for linux/amd64 and linux/arm64 architectures.

Features

• TCP connectivity: Wait for services to be accessible via TCP (using host:port format)
• Shell command: Execute arbitrary shell commands and wait for successful completion
• Configurable timeouts: Customizable sleep intervals and timeout periods
• User-friendly output: Clear progress indicators and status messages
• Multi-architecture support: Available for linux/amd64 and linux/arm64

Example usage:

TCP Connectivity

Wait for services to accept TCP connections on specific ports:

services:
  database:
    image: postgres:15-alpine
    environment:
      POSTGRES_PASSWORD: secret
    ports:
      - "5432:5432"

  cache:
    image: redis:7-alpine
    ports:
      - "6379:6379"

  app:
    image: alpine:3.22
    depends_on:
      # Will start only after the wait-for-dependencies finishes waiting
      # for both database and cache to be reachable.
      wait-for-dependencies:
        condition: service_completed_successfully
    ports:
      - "8000:8000"

  wait-for-dependencies:
    image: drevops/docker-wait-for-dependencies:25.9.0
    depends_on:
      - database
      - cache
    command: database:5432 cache:6379

Combined TCP and Health Check Commands

Wait for both TCP connectivity and custom health check endpoints:

services:
  api:
    image: php:8.3-cli-alpine
    ports:
      - "8080:8080"
    command: php -S 0.0.0.0:8080 -t /app

  worker:
    image: alpine:3.18
    ports:
      - "9000:9000"
    command: nc -l -p 9000

  app:
    image: alpine:3.22
    depends_on:
      # Will start only after the wait-for-dependencies finishes waiting
      # for both api and worker to be reachable.
      wait-for-dependencies:
        condition: service_completed_successfully
    ports:
      - "8000:8000"

  wait-for-dependencies:
    image: drevops/docker-wait-for-dependencies:25.9.0
    depends_on:
      - api
      - worker
    command:
      - api:8080
      - worker:9000
      - "curl -f http://api:8080/health"
      - "test -S /var/run/app.sock"

Configuration

The container supports the following environment variables:

Variable	Default	Description
SLEEP_LENGTH	2	Time (in seconds) to wait between each check attempt
TIMEOUT_LENGTH	300	Maximum time (in seconds) to wait before giving up
SUMMARY_ENABLED	true	Show summary message when all checks complete successfully

Development & Maintenance

npm run lint # Lint shell scripts and Dockerfile
npm run lint-fix # Auto-fix formatting issues
npm run test-unit # Run unit tests for validation logic
npm run test-functional # Run end-to-end tests with Docker

Versioning

This project uses CalVer versioning:

• YY: Last two digits of the year, e.g., 25 for 2025.
• m: Numeric month, e.g., April is 4.
• patch: Patch number for the month, starting at 0.

Example: 25.4.2 indicates the third patch in April 2025.

Releasing

Releases are scheduled to occur at a minimum of once per month.

The cross-platform images are built by GitHub actions and pushed to DockerHub:

• YY.m.patch tag - when release tag is published on GitHub.
• latest - when release tag is published on GitHub.
• canary - on every push to main branch

Dependencies update

Renovate bot is used to update dependencies. It creates a PR with the changes and automatically merges it if CI passes. These changes are then released as a canary version.

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