docker postgresql のhealth checkの備忘録

TL;DR

1. dockerのpostresql containerにhealthcheck blockを追加
2. test block内に　pg_isready commandを利用したhealth check コマンドを追加する
3. application container 側のdepends_on blockに　db:　condition: service_healthyを追加

0. 参考

docker blog
postgre docker image
docker compose reference
peter-evans/docker-compose-healthcheck #17

1. postgresql imageの準備をする

tree ${PROJECT_PATH} -L 2
${PROJECT_PATH}
├── README.md
├── compose.yaml
├── database
│   └── dockerfile

${PROJECT_PATH}/compose.yaml

services:
  database_container:
    container_name: database_container
    build:
      context: ./database
      dockerfile: dockerfile
    tty: true
    restart: always
    ports:
      - "5432:5432"
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: example
      POSTGRES_USER: example

volumes:
  pgdata: {}

FROM postgres:16

2. healthcheck blockを追加する

docker blogを参考に、health check blockの追加を実施。

${PROJECT_PATH}/compose.yaml

services:
  database_container:
      container_name: database_container
      # ...
      # 追記
      healthcheck:
      test: ["CMD-SHELL", "pg_isready"]
      interval: 1s
      timeout: 5s
      retries: 10

% docker compose up --build
database_container  | 2024-08-25 08:17:56.724 UTC [40] FATAL:  role "root" does not exist

role "root" does not existとなってしまい、まぁ起動しているから追加すれば良いのですが、毎回でるの辛いので、pg_isreadyから確認する。

3. health check blockを修正する

-U username
--username=username
Connect to the database as the user username instead of the default.
https://www.postgresql.org/docs/current/app-pg-isready.html

peter-evans/docker-compose-healthcheck issues 17
peter-evans/docker-compose-healthcheck issues 17

上記から、container > healthcheck > testコマンドないでuserを設定して渡らせる。

${PROJECT_PATH}/compose.yaml

services:
  database_container:
    container_name: database_container
    build:
      context: ./database
      dockerfile: dockerfile
    tty: true
    restart: always
    ports:
      - "5432:5432"
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: example
      POSTGRES_USER: example
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER}"]
      interval: 1s
      timeout: 5s
      retries: 10

docker compose up --build
database_container  | 2024-08-25 08:19:17.311 UTC [1] LOG:  database system is ready to accept connections
database_container  | 2024-08-25 08:24:17.340 UTC [27] LOG:  checkpoint starting: time