Docker Compose Wait til dependency container is fully up before launching

问题

I'm working with a docker service using docker-compose, and I have a service that depends on anther.

I've used the depends_on key, but the service with the dependency launches prior to the depending service being completely up.

version: '3'

services:
  KeyManager:
    image: cjrutherford/keymanager
    deploy:
      replicas: 1
    ports:
      - '3220:3220'
    networks:
      - privnet
  YellowDiamond:
    image: cjrutherford/server
    depends_on:
      - KeyManager
    deploy:
      replicas: 1
    ports:
      - '3000:3000'
    networks:
      - privnet
      - web
networks:
  privnet:
    internal: true
  web:

Both of these are node applications, and the keymanager is required to be running to accept requests before the server launches. Can I add a timeout? or send a trigger in the app? it's just launching way too early to get the key from the manager.

回答1:

I've often found using a wait-for-it bash script much more effective than the built in health check to docker-compose.

This runs a TCP health check against a given port and waits until this is complete before starting to run a process.

Sample code:

version: "2"
services:
  web:
    build: .
    ports:
      - "80:8000"
    depends_on:
      - "db"
    command: ["./wait-for-it.sh", "db:5432", "--", "python", "app.py"]
  db:
    image: postgres

Here's some docs:

https://docs.docker.com/compose/startup-order/
https://github.com/vishnubob/wait-for-it

回答2:

You are probably looking for docker compose healthcheck

healthcheck:
  test: ["CMD-SHELL", "pg_isready -U postgres"]
  interval: 10s
  timeout: 5s
  retries: 5

There is a good reference here as well:
https://github.com/peter-evans/docker-compose-healthcheck

来源：https://stackoverflow.com/questions/55502234/docker-compose-wait-til-dependency-container-is-fully-up-before-launching

标签

Docker

docker-compose