Building and Running a Custom MySQL Image with Docker and Verification

In this Dockerfile, you've set the environment variable for the MySQL database name. You can also use the `COPY` instruction to add custom configuration files or scripts into the container. In this example, files from your host's `./scripts/` directory are copied into the container's `/docker-entrypoint-initdb.d/` directory. In this directory, `.sh`, `.sql`, and `.sql.gz` scripts are executed when the container is started for the first time. For more details about Dockerfiles, see the [Dockerfile reference](/reference/dockerfile/). 3. Create a script file to initialize a table in the database. In the directory where your `Dockerfile` is located, create a subdirectory named `scripts`, and then create a file named `create_table.sql` with the following content. ```text CREATE TABLE IF NOT EXISTS mydb.myothertable ( column_name VARCHAR(255) ); INSERT INTO mydb.myothertable (column_name) VALUES ('other_value'); ``` You should now have the following directory structure. ```text ├── your-project-directory/ │ ├── scripts/ │ │ └── create_table.sql │ └── Dockerfile ``` 2. Build your image. 1. In a terminal, change directory to the directory where your `Dockerfile` is located. 2. Run the following command to build the image. ```console $ docker build -t my-custom-mysql . ``` In this command, `-t my-custom-mysql` tags (names) your new image as `my-custom-mysql`. The period (.) at the end of the command specifies the current directory as the context for the build, where Docker looks for the Dockerfile and any other files needed for the build. 3. Run your image as you did in [Run a local containerized database](#run-a-local-containerized-database). This time, specify your image's name instead of `mysql:latest`. Also, you no longer need to specify the `MYSQL_DATABASE` environment variable as it's now defined by your Dockerfile. ```console $ docker run --name my-mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d my-custom-mysql ``` 4. Verify that your container is running with the following command. ```console $ docker ps ``` You should see output like the following. ```console CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES f74dcfdb0e59 my-custom-mysql "docker-entrypoint.s…" 2 hours ago Up 51 minutes 3306/tcp, 33060/tcp my-mysql ``` 5. Verify that your initialization script was ran. Run the following command in a terminal to show the contents of the `myothertable` table. ```console $ docker exec my-mysql mysql -u root -pmy-secret-pw -e "SELECT * FROM mydb.myothertable;" ``` You should see output like the following. ```console column_name other_value ``` Any container ran using your `my-custom-mysql` image will have the table initialized when first started. ## Use Docker Compose to run a database Docker Compose is a tool for defining and running multi-container Docker applications. With a single command, you can configure all your application's services (like databases, web apps, etc.) and manage them. In this example, you'll create a Compose file and use it to run a MySQL database container and a phpMyAdmin container. To run your containers with Docker Compose:

This section details how to build a custom MySQL Docker image by creating a Dockerfile, adding a script to initialize a table in the database, and building the image using the `docker build` command. It then guides on how to run the custom image, verifying that the container is running and that the initialization script was executed correctly by querying the newly created table. Finally, it introduces Docker Compose as a tool for managing multi-container Docker applications, specifically for running a MySQL database container along with a phpMyAdmin container.