Fix database with pytest-docker

The following is prepared as "Pytest environment example to fix the database with Docker".

-Qiita article

• GitHub

This article was MySQL, but I also checked it with PostgreSQL.

As a library of database connection interface,

--For MySQL: PyMySQL --For PostgreSQL: psycopg2

I used, but I think it is almost the same when using other things.

Fix fixture example in conftest.py

In the sample of pytest-docker, waiting for the startup of httpbin,

def is_responsive(url):
    try:
        response = requests.get(url)
        if response.status_code == 200:
            return True
    except ConnectionError:
        return False


@pytest.fixture(scope="session")
def http_service(docker_ip, docker_services):
    """Ensure that HTTP service is up and responsive."""

    # `port_for` takes a container port and returns the corresponding host port
    port = docker_services.port_for("httpbin", 80)
    url = "http://{}:{}".format(docker_ip, port)
    docker_services.wait_until_responsive(
        timeout=30.0, pause=0.1, check=lambda: is_responsive(url)
    )
    return url

Database version of this. On the application side, even when using ORM such as SQLAlchemy, I tried connecting with the direct connection library. I'm not sure if it's the timing of SQLAlchemy's create_engine () via ORM. It's like making it clear that you are connecting via the driver library and checking the startup.

For MySQL container

Wait until the MySQL container starts up and there are no exceptions to connect ()

def is_mysqld_ready(docker_ip):
    try:
        pymysql.connect(
            host=docker_ip,
            user=os.getenv('MYSQL_USER', ''),
            password=os.getenv('MYSQL_PASSWORD', ''),
            db=os.getenv('MYSQL_DATABASE', '')
        )
        return True
    except:
        return False

@pytest.fixture(scope="session")
def database_service(docker_ip, docker_services):
    docker_services.wait_until_responsive(
        timeout=30.0, pause=0.1, check=lambda: is_mysqld_ready(docker_ip)
    )
    return

For PostgreSQL container

It's the same.

def is_postgresql_ready(docker_ip):
    try:
        psycopg2.connect(
            "postgresql://{user}:{password}@{host}/{db}".format(
                user=os.getenv('POSTGRES_USER', ''),
                password=os.getenv('POSTGRES_PASSWORD', ''),
                host=docker_ip,
                db=os.getenv('POSTGRES_DB', '')
            )
        )
        return True
    except:
        return False

@pytest.fixture(scope="session")
def database_service(docker_ip, docker_services):
    docker_services.wait_until_responsive(
        timeout=30.0, pause=0.1, check=lambda: is_postgresql_ready(docker_ip)
    )
    return

docker-compose.yml

#For MySQL
version: "3"

services:
  database:
    image: mysql:5.7
    ports:
      - 3306:3306
    volumes:
      - ./initdb.d:/docker-entrypoint-initdb.d
    environment:
      - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
      - MYSQL_USER=${MYSQL_USER}
      - MYSQL_PASSWORD=${MYSQL_PASSWORD}
      - MYSQL_DATABASE=${MYSQL_DATABASE}

#For PostgreSQL
version: "3"

services:
  database:
    image: postgres:13
    ports:
      - 5432:5432
    volumes:
      - ./initdb.d:/docker-entrypoint-initdb.d
    environment:
      - POSTGRES_USER=${POSTGRES_USER}
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
      - POSTGRES_DB=${POSTGRES_DB}

Schema and test data preparation

After that, the SQL and initialization shell script etc. are thrown into the ./initdb.d folder of ./initdb.d:/docker-entrypoint-initdb.d which is volume mounted and initialized by docker-compose. If you do, you can test it.

In the Qiita article, Initialize data when starting MySQL with Docker.