;; MSG SIZE  rcvd: 44
   ```

   In the "ANSWER SECTION", you will see an `A` record for `mysql` that resolves to `172.23.0.2`
   (your IP address will most likely have a different value). While `mysql` isn't normally a valid hostname,
   Docker was able to resolve it to the IP address of the container that had that network alias. Remember, you used the
   `--network-alias` earlier.

   What this means is that your app only simply needs to connect to a host named `mysql` and it'll talk to the
   database.

## Run your app with MySQL

The todo app supports the setting of a few environment variables to specify MySQL connection settings. They are:

- `MYSQL_HOST` - the hostname for the running MySQL server
- `MYSQL_USER` - the username to use for the connection
- `MYSQL_PASSWORD` - the password to use for the connection
- `MYSQL_DB` - the database to use once connected

> [!NOTE]
>
> While using env vars to set connection settings is generally accepted for development, it's highly discouraged
> when running applications in production. Diogo Monica, a former lead of security at Docker,
> [wrote a fantastic blog post](https://diogomonica.com/2017/03/27/why-you-shouldnt-use-env-variables-for-secret-data/)
> explaining why.
>
> A more secure mechanism is to use the secret support provided by your container orchestration framework. In most cases,
> these secrets are mounted as files in the running container. You'll see many apps (including the MySQL image and the todo app)
> also support env vars with a `_FILE` suffix to point to a file containing the variable.
>
> As an example, setting the `MYSQL_PASSWORD_FILE` var will cause the app to use the contents of the referenced file
> as the connection password. Docker doesn't do anything to support these env vars. Your app will need to know to look for
> the variable and get the file contents.

You can now start your dev-ready container.

1. Specify each of the previous environment variables, as well as connect the container to your app network. Make sure that you are in the `getting-started-app` directory when you run this command.

   {{< tabs >}}
   {{< tab name="Mac / Linux" >}}

   ```console
   $ docker run -dp 127.0.0.1:3000:3000 \
     -w /app -v "$(pwd):/app" \
     --network todo-app \
     -e MYSQL_HOST=mysql \
     -e MYSQL_USER=root \
     -e MYSQL_PASSWORD=secret \
     -e MYSQL_DB=todos \
     node:18-alpine \
     sh -c "yarn install && yarn run dev"
   ```
   
   {{< /tab >}}
   {{< tab name="PowerShell" >}}
   In Windows, run this command in PowerShell.

   ```powershell
   $ docker run -dp 127.0.0.1:3000:3000 `
     -w /app -v "$(pwd):/app" `
     --network todo-app `
     -e MYSQL_HOST=mysql `
     -e MYSQL_USER=root `
     -e MYSQL_PASSWORD=secret `
     -e MYSQL_DB=todos `
     node:18-alpine `
     sh -c "yarn install && yarn run dev"
   ```

   {{< /tab >}}
   {{< tab name="Command Prompt" >}}
   In Windows, run this command in Command Prompt.

   ```console
   $ docker run -dp 127.0.0.1:3000:3000 ^