Docker-compose does not wait for any container to be “ready” before going ahead with the next containers. In order to achieve the order of execution, we can use:
- The “depends_on” which got added in version 2 of docker-compose can be used as shown in a sample docker-compose.yml file below:
version: "2.4"
services:
backend:
build: .
depends_on:
- db
db:
image: postgres
The introduction of service dependencies has various causes and effects:
- The
docker-compose up command starts and runs the services in the dependency order specified. For the above example, the DB container is started before the backend.
docker-compose up SERVICE_NAME by default includes the dependencies associated with the service. In the given example, running docker-compose up backend creates and starts DB (dependency of backend).- Finally, the command
docker-compose stop also stops the services in the order of the dependency specified. For the given example, the backend service is stopped before the DB service.
