2. Select **set up a workflow yourself**.

   This takes you to a page for creating a new GitHub Actions workflow file in
   your repository. By default, the file is created under `.github/workflows/main.yml`, let's change it name to `build.yml`.

If you prefer to use your text editor, create a new file named `build.yml` in the `.github/workflows/` directory of your repository.

Add the following content to the file:

```yaml
name: Build and push Docker image

on:
  push:
    branches:
      - main

jobs:
  build_and_push:
    runs-on: ubuntu-latest
    steps:
      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          push: true
          tags: ${{ vars.DOCKER_USERNAME }}/${{ github.event.repository.name }}:latest
```

Each GitHub Actions workflow includes one or several jobs. Each job consists of steps. Each step can either run a set of commands or use already [existing actions](https://github.com/marketplace?type=actions). The action above has three steps:

1. [**Login to Docker Hub**](https://github.com/docker/login-action): Action logs in to Docker Hub using the Docker ID and Personal Access Token (PAT) you created earlier.

2. [**Set up Docker Buildx**](https://github.com/docker/setup-buildx-action): Action sets up Docker [Buildx](https://github.com/docker/buildx), a CLI plugin that extends the capabilities of the Docker CLI.

3. [**Build and push**](https://github.com/docker/build-push-action): Action builds and pushes the Docker image to Docker Hub. The `tags` parameter specifies the image name and tag. The `latest` tag is used in this example.

## 2. Run the workflow

Let's commit the changes, push them to the `main` branch. In the workflow above, the trigger is set to `push` events on the `main` branch. This means that the workflow will run every time you push changes to the `main` branch. You can find more information about the workflow triggers [here](https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows).

Go to the **Actions** tab of you GitHub repository. It displays the workflow. Selecting the workflow shows you the breakdown of all the steps.

When the workflow is complete, go to your [repositories on Docker Hub](https://hub.docker.com/repositories). If you see the new repository in that list, it means the GitHub Actions workflow successfully pushed the image to Docker Hub.

## Summary

In this section, you learned how to set up a GitHub Actions workflow for your Ruby on Rails application.

Related information:

- [Introduction to GitHub Actions](/guides/gha.md)
- [Docker Build GitHub Actions](/manuals/build/ci/github-actions/_index.md)
- [Workflow syntax for GitHub Actions](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions)

## Next steps

In the next section, you'll learn how you can develop your application using containers.