Wait for other services to become available

./wait-for is a script designed to synchronize services like docker containers. It is sh and alpine compatible. It was inspired by vishnubob/wait-for-it, but the core has been rewritten at Eficode by dsuni and mrako.

When using this tool, you only need to pick the wait-for file as part of your project.

Usage

./wait-for host:port [host:port] [-t timeout] [-- command args]
  -q | --quiet                        Do not output any status messages
  -t TIMEOUT | --timeout=timeout      Timeout in seconds, zero for no timeout
  -- COMMAND ARGS                     Execute command with args after the test finishes

Examples

To check if eficode.com is available:

$ ./wait-for www.eficode.com:80 -- echo "Eficode site is up"

Connection to www.eficode.com port 80 [tcp/http] succeeded!
Eficode site is up

To wait for database container to become available:

version: '2'

services:
  db:
    image: postgres:9.4

  backend:
    build: backend
    command: sh -c '/scripts/wait-for db:5432 -- npm start'
    volumes:
      - scripts-volume:/scripts
    depends_on:
      - db

  scripts:
    image: hhxiao/wait-for
    volumes:
      - scripts-volume:/wait-for

volumes:
  scripts-volume:

To wait for kafka and cassandra container to become available:

version: '2'

services:
  cassandra:
    image: cassandra:3.10
    ports:
      - "9042:9042"

  kafka:
    image: spotify/kafka
    ports:
      - "2181:2181"
      - "9092:9092"
    environment:
      - ADVERTISED_HOST=kafka
      - ADVERTISED_PORT=9092

  backend:
    build: backend
    command: sh -c '/scripts/wait-for cassandra:9042 kafka:9092 -- npm start'
    volumes:
      - scripts-volume:/scripts
    depends_on:
    - cassandra
    - kafka

    scripts:
      image: hhxiao/wait-for
      volumes:
        - scripts-volume:/wait-for

  volumes:
    scripts-volume:

Testing

Ironically testing is done using bats, which on the other hand is depending on bash.

docker build -t wait-for .
docker run -t wait-for