docker-compose.ymlでpgbouncerを利用するサンプル

.env

DATABASES_HOST=hostname-of-database
DATABASES_USER=database-user-name
DATABASES_PASSWORD=database-password

pgbouncer.yml

  # https://inside.pixiv.blog/sue445/7729
  pgbouncer:
    restart: always
    image: pgbouncer/pgbouncer:1.10.0
    # depends_on:
    # - db

    # 設定値は下記を参照
    # * Dockerイメージの環境変数: https://gitlab.com/aztek-io/pgbouncer-container/blob/master/entrypoint.sh
    # * pgbouncer.iniの設定: https://pgbouncer.github.io/config.html
    env_file:
     - .env
    environment:
    - DATABASES_PORT=5432
    - PGBOUNCER_LISTEN_PORT=5432

    # c.f.
    # * https://about.gitlab.com/2017/10/02/scaling-the-gitlab-database/
    # * https://gitlab.com/gitlab-org/omnibus-gitlab/blob/c7fda3c84dc57fafe830b3318d337c6fea68eae5/files/gitlab-cookbooks/gitlab-ee/attributes/default.rb#L159-261
    - PGBOUNCER_DEFAULT_POOL_SIZE=100
    - PGBOUNCER_RESERVE_POOL_SIZE=5
    - PGBOUNCER_RESERVE_POOL_TIMEOUT=3
    - PGBOUNCER_MAX_CLIENT_CONN=2048
    - PGBOUNCER_POOL_MODE=transaction
    - PGBOUNCER_SERVER_IDLE_TIMEOUT=30
    healthcheck:
      # pgbouncerが起動しきるまで待つ
      # FIXME: できればPostgreSQLに接続可能になるまで待ちたいのだがpsqlが入っていないので厳しい
      test: ps aux | grep -v grep | grep pgbouncer
      interval: 1s
      timeout: 5s
      retries: 30
      # FIXME: 念の為待つ
      start_period: 30s
    # deploy:
    #   restart_policy:
    #     condition: on-failure
    #   update_config:
    #     parallelism: 1
    #     delay: 1s
    #     order: start-first