Postgres docker service now fails to start without "POSTGRES_HOST_AUTH_METHOD: trust" option

Problem to solve

• To use the most recent postgres docker image, it now requires an additional option POSTGRES_HOST_AUTH_METHOD: trust which is not currently listed on the section of the documentation: https://docs.gitlab.com/ee/ci/services/postgres.html

• Sources:

  • https://gitlab.com/gitlab-com/support-forum/issues/5199#note_288766448
  • https://github.com/docker-library/postgres/issues/681

Further details

• Before the weekend the following configuration was working flawlessly:

test-api:
  stage: test
  image: node:13.8.0-alpine
  services:
    - postgres:10-alpine
  only:
    - merge_requests
  variables:
    POSTGRES_DB: nice_marmot
    POSTGRES_USER: runner
    POSTGRES_PASSWORD: ""

• Out the blue after the weekend, it stopped working showing the error

Service runner-ed2dce3a-project-4556663-concurrent-0-postgres-0 probably didn't start properly.
 Health check error:
 ContainerStart: Error response from daemon: Cannot link to a non running container: /runner-ed2dce3a-project-4556663-concurrent-0-postgres-0 AS /runner-ed2dce3a-project-4556663-concurrent-0-postgres-0-wait-for-service/service (executor_docker.go:1259:0s)
 Service container logs:
 2020-02-17T13:35:29.470574649Z Error: Database is uninitialized and superuser password is not specified.
 2020-02-17T13:35:29.470606915Z        You must specify POSTGRES_PASSWORD for the superuser. Use
 2020-02-17T13:35:29.470611569Z        "-e POSTGRES_PASSWORD=password" to set it in "docker run".
 2020-02-17T13:35:29.470615118Z
 2020-02-17T13:35:29.470618049Z        You may also use POSTGRES_HOST_AUTH_METHOD=trust to allow all connections
 2020-02-17T13:35:29.470621289Z        without a password. This is *not* recommended. See PostgreSQL
 2020-02-17T13:35:29.470624357Z        documentation about "trust":
 2020-02-17T13:35:29.470627495Z        https://www.postgresql.org/docs/current/auth-trust.html
 *********

• Adding the variable POSTGRES_HOST_AUTH_METHOD: trust fixes the issue

Proposal

• The documentation (https://docs.gitlab.com/ee/ci/services/postgres.html) should indicate the existence of the variable :)