Docker-Compose:如何等待其他服务准备就绪? [英] Docker-Compose: how to wait for other service to be ready?

问题描述

我有以下 docker-compose，在启动 myprogram-app 之前，我需要等待服务 jhipster-registry 启动并接受连接.

I have the following docker-compose, where I need to wait for the service jhipster-registry to be up and accepting connections before starting myprogram-app.

我按照官方文档https://docs.docker.com/compose/compose-file/compose-file-v2/

version: '2.1'
services:
    myprogram-app:
        image: myprogram
        mem_limit: 1024m
        environment:
            - SPRING_PROFILES_ACTIVE=prod,swagger
            - EUREKA_CLIENT_SERVICE_URL_DEFAULTZONE=http://admin:$${jhipster.registry.password}@jhipster-registry:8761/eureka
            - SPRING_CLOUD_CONFIG_URI=http://admin:$${jhipster.registry.password}@jhipster-registry:8761/config
            - SPRING_DATASOURCE_URL=jdbc:postgresql://myprogram-postgresql:5432/myprogram
            - JHIPSTER_SLEEP=0
            - SPRING_DATA_ELASTICSEARCH_CLUSTER_NODES=myprogram-elasticsearch:9300
            - JHIPSTER_REGISTRY_PASSWORD=53bqDrurQAthqrXG
            - EMAIL_USERNAME
            - EMAIL_PASSWORD
        ports:
            - 8080:8080
        networks:
          - backend
        depends_on:
          - jhipster-registry:
              "condition": service_started
          - myprogram-postgresql
          - myprogram-elasticsearch
    myprogram-postgresql:
        image: postgres:9.6.5
        mem_limit: 256m
        environment:
            - POSTGRES_USER=myprogram
            - POSTGRES_PASSWORD=myprogram
        networks:
          - backend
    myprogram-elasticsearch:
        image: elasticsearch:2.4.6
        mem_limit: 512m
        networks:
          - backend
    jhipster-registry:
        extends:
            file: jhipster-registry.yml
            service: jhipster-registry
        mem_limit: 512m
        ports:
            - 8761:8761
        networks:
          - backend
        healthcheck:
          test: "exit 0"
networks:
  backend:
    driver: "bridge"

但是在运行 docker-compose up 时出现以下错误:

but I get the following error when running docker-compose up:

ERROR: The Compose file './docker-compose.yml' is invalid because:
services.myprogram-app.depends_on contains {"jhipster-registry": {"condition": "service_started"}}, which is an invalid type, it should be a string

我做错了什么，还是不再支持此功能?如何在服务之间实现这种同步?

Am I doing something wrong, or this feature is no more supported? How to achieve this sync between services?

更新版本

version: '2.1'
services:
    myprogram-app:
        image: myprogram
        mem_limit: 1024m
        environment:
            - SPRING_PROFILES_ACTIVE=prod,swagger
            - EUREKA_CLIENT_SERVICE_URL_DEFAULTZONE=http://admin:$${jhipster.registry.password}@jhipster-registry:8761/eureka
            - SPRING_CLOUD_CONFIG_URI=http://admin:$${jhipster.registry.password}@jhipster-registry:8761/config
            - SPRING_DATASOURCE_URL=jdbc:postgresql://myprogram-postgresql:5432/myprogram
            - JHIPSTER_SLEEP=0
            - SPRING_DATA_ELASTICSEARCH_CLUSTER_NODES=myprogram-elasticsearch:9300
            - JHIPSTER_REGISTRY_PASSWORD=53bqDrurQAthqrXG
            - EMAIL_USERNAME
            - EMAIL_PASSWORD
        ports:
            - 8080:8080
        networks:
          - backend
        depends_on:
          jhipster-registry:
            condition: service_healthy
          myprogram-postgresql:
            condition: service_started
          myprogram-elasticsearch:
            condition: service_started
        #restart: on-failure
    myprogram-postgresql:
        image: postgres:9.6.5
        mem_limit: 256m
        environment:
            - POSTGRES_USER=myprogram
            - POSTGRES_PASSWORD=tuenemreh
        networks:
          - backend
    myprogram-elasticsearch:
        image: elasticsearch:2.4.6
        mem_limit: 512m
        networks:
          - backend
    jhipster-registry:
        extends:
            file: jhipster-registry.yml
            service: jhipster-registry
        mem_limit: 512m
        ports:
            - 8761:8761
        networks:
          - backend
        healthcheck:
          test: ["CMD", "curl", "-f", "http://jhipster-registry:8761", "|| exit 1"]
          interval: 30s
          retries: 20
          #start_period: 30s
networks:
  backend:
    driver: "bridge"

更新的版本给了我一个不同的错误，

The updated version gives me a different error,

ERROR: for myprogram-app  Container "8ebca614590c" is unhealthy.
ERROR: Encountered errors while bringing up the project.

说jhipster-registry的容器不健康，但是可以通过浏览器访问.如何修复健康检查中的命令以使其正常工作?

saying that the container of jhipster-registry is unhealthy, but it's reachable via browser. How can I fix the command in the healthcheck to make it work?

推荐答案

文档 表明，在 Docker Compose 版本 2 文件中，depends_on: 可以是字符串列表，或者是键所在的映射服务名称和值是条件.对于您没有(或不需要)健康检查的服务，有一个 service_started 条件.

The documentation suggests that, in Docker Compose version 2 files specifically, depends_on: can be a list of strings, or a mapping where the keys are service names and the values are conditions. For the services where you don't have (or need) health checks, there is a service_started condition.

depends_on:
  # notice: these lines don't start with "-"
  jhipster-registry:
    condition: service_healthy
  myprogram-postgresql:
    condition: service_started
  myprogram-elasticsearch:
    condition: service_started

根据您对程序及其库的控制程度，如果您可以安排服务能够在其依赖项不一定可用的情况下启动(等效地，如果其依赖项在服务期间死亡，则可以正常运行)更好正在运行)，而不是使用 depends_on: 选项.例如，如果数据库关闭，您可能会返回 HTTP 503 服务不可用错误.另一个通常有用的策略是，如果您的依赖项不可用，则立即退出，但使用 一个设置，比如restart: on-error 来要求协调器重启服务.

Depending on how much control you have over your program and its libraries, it's better still if you can arrange for the service to be able to start without its dependencies necessarily being available (equivalently, to function if its dependencies die while the service is running), and not use the depends_on: option. You might return an HTTP 503 Service Unavailable error if the database is down, for instance. Another strategy that often is helpful is to immediately exit if your dependencies aren't available but use a setting like restart: on-error to ask the orchestrator to restart the service.

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