- db-data:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=example
      - POSTGRES_PASSWORD_FILE=/run/secrets/db-password
    expose:
      - 5432
    healthcheck:
      test: ["CMD", "pg_isready"]
      interval: 10s
      timeout: 5s
      retries: 5
volumes:
  db-data:
secrets:
  db-password:
    file: db/password.txt
```

> [!NOTE]
>
> To learn more about the instructions in the Compose file, see [Compose file
> reference](/reference/compose-file/).

Before you run the application using Compose, notice that this Compose file uses
`secrets` and specifies a `password.txt` file to hold the database's password.
You must create this file as it's not included in the source repository.

In the `docker-dotnet-sample` directory, create a new directory named `db` and
inside that directory create a file named `password.txt`. Open `password.txt` in an IDE or text editor and add the following password. The password must be on a single line, with no additional lines in the file.

```text
example
```

Save and close the `password.txt` file.

You should now have the following in your `docker-dotnet-sample` directory.

```text
├── docker-dotnet-sample/
│ ├── .git/
│ ├── db/
│ │ └── password.txt
│ ├── src/
│ ├── tests/
│ ├── .dockerignore
│ ├── .gitignore
│ ├── compose.yaml
│ ├── Dockerfile
│ ├── README.Docker.md
│ └── README.md
```

Run the following command to start your application.

```console
$ docker compose up --build
```

Open a browser and view the application at [http://localhost:8080](http://localhost:8080). You should see a simple web application with the text `Student name is`.

The application doesn't display a name because the database is empty. For this application, you need to access the database and then add records.

## Add records to the database

For the sample application, you must access the database directly to create sample records.

You can run commands inside the database container using the `docker exec`
command. Before running that command, you must get the ID of the database
container. Open a new terminal window and run the following command to list all
your running containers.

```console
$ docker container ls
```

You should see output like the following.

```console
CONTAINER ID   IMAGE                  COMMAND                  CREATED              STATUS                        PORTS                    NAMES
cb36e310aa7e   docker-dotnet-server   "dotnet myWebApp.dll"    About a minute ago   Up About a minute             0.0.0.0:8080->8080/tcp   docker-dotnet-server-1
39fdcf0aff7b   postgres               "docker-entrypoint.s…"   About a minute ago   Up About a minute (healthy)   5432/tcp                 docker-dotnet-db-1
```

In the previous example, the container ID is `39fdcf0aff7b`. Run the following command to connect to the postgres database in the container. Replace the container ID with your own container ID.

```console
$ docker exec -it 39fdcf0aff7b psql -d example -U postgres
```

And finally, insert a record into the database.

```console
example=# INSERT INTO "Students" ("ID", "LastName", "FirstMidName", "EnrollmentDate") VALUES (DEFAULT, 'Whale', 'Moby', '2013-03-20');
```

You should see output like the following.

```console
INSERT 0 1
```

Close the database connection and exit the container shell by running `exit`.

```console
example=# exit
```

## Verify that data persists in the database

Open a browser and view the application at [http://localhost:8080](http://localhost:8080). You should see a simple web application with the text `Student name is Whale Moby`.

Press `ctrl+c` in the terminal to stop your application.

In the terminal, run `docker compose rm` to remove your containers and then run `docker compose up` to run your application again.

```console
$ docker compose rm
$ docker compose up --build
```

Refresh [http://localhost:8080](http://localhost:8080) in your browser and verify that the student name persisted, even after the containers were removed and ran again.