How to connect to a database in a Docker container?

Follow these steps to connect to a database in a Docker container:

1. Start the Docker Daemon:

Open a terminal and start the Docker daemon. The Docker daemon listens for Docker API requests and manages Docker objects such as images, containers, networks. \`\`\` sudo service docker start \`\`\`

1. Run your database in a Docker container:

\`\`\`bash docker run —name some-mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -p 3306:3306 -d mysql \`\`\` This command does several things: - `docker run` creates a new container. - `—name` assigns a name to the container. - `-e` sets environment variables (`MYSQL_ROOT_PASSWORD`). - `-p` publishes the container’s port(s) to the host. - `-d` runs the container in detached mode. - `mysql` is the name of the image from Docker Hub to base the container on.

1. Identify your Docker container’s IP address:

You can check the IP address assigned to your running Docker container using the `docker inspect` command: \`\`\`bash docker inspect | grep IPAddress \`\`\` Replace `` with the ID of your running Docker container.

1. Connect to your database:

Now, you need to use a tool or programming language to connect to your database.

- For MySQL/MariaDB, you might use the `mysql` command which is included in those databases:

\`\`\`bash mysql -h -P -u root -p \`\`\`

- `mysql` is the MySQL command line tool.
- `-h` is the IP address to connect to (the Docker container’s IP).
- `-P` is the port to connect on which Docker has mapped and exposed.
- `-u` is the user that you’re connecting as.
- `-p` will cause MySQL to prompt you for your password.

Or you can use the localhost (127.0.0.1) instead of the docker-ip-address if the container port is mapped to the host:

```
mysql -h 127.0.0.1 -P -u root -p
```

For programming languages you usually use a connection string:

- Python Example:

```
import mysql.connector

cnx = mysql.connector.connect(user=‘root’, password=‘my-secret-pw’, host=‘127.0.0.1’, database=‘test’)
cnx.close()
```

Just replace `host` and `port` with the details of your Dockerized database.

Replace `user` and `password` with the credentials for your database. Replace `database` with the name of your database. Replace `127.0.0.1` with your Docker container’s IP address if it is not mapping ports to the host.