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docker-compose depends_on官方文档说明

depends_on

depends_on expresses startup and shutdown dependencies between services.

Short syntax

The short syntax variant only specifies service names of the dependencies. Service dependencies cause the following behaviors:

Compose creates services in dependency order. In the following example, db and redis are created before web.
Compose removes services in dependency order. In the following example, web is removed before db and redis.

Simple example:

services:
  web:
    build: .
    depends_on:
      - db
      - redis
  redis:
    image: redis
  db:
    image: postgres

Compose guarantees dependency services have been started before starting a dependent service. Compose waits for dependency services to be "ready" before starting a dependent service.

Long syntax

The long form syntax enables the configuration of additional fields that can't be expressed in the short form.

restart: When set to true Compose restarts this service after it updates the dependency service. This applies to an explicit restart controlled by a Compose operation, and excludes automated restart by the container runtime after the container dies.
condition: Sets the condition under which dependency is considered satisfied
- service_started: An equivalent of the short syntax described above
- service_healthy: Specifies that a dependency is expected to be "healthy" (as indicated by healthcheck) before starting a dependent service.
- service_completed_successfully: Specifies that a dependency is expected to run to successful completion before starting a dependent service.
required: When set to false Compose only warns you when the dependency service isn't started or available. If it's not defined the default value of required is true.

Service dependencies cause the following behaviors:

Compose creates services in dependency order. In the following example, db and redis are created before web.
Compose waits for healthchecks to pass on dependencies marked with service_healthy. In the following example, db is expected to be "healthy" before web is created.
Compose removes services in dependency order. In the following example, web is removed before db and redis.

services:
  web:
    build: .
    depends_on:
      db:
        condition: service_healthy
        restart: true
      redis:
        condition: service_started
  redis:
    image: redis
  db:
    image: postgres

Compose guarantees dependency services are started before starting a dependent service. Compose guarantees dependency services marked with service_healthy are "healthy" before starting a dependent service.

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