buildah-build/README.md

# buildah
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Buildah is a GitHub Action for building Docker and Kubernetes-compatible images quickly and easily.

Buildah only works on Linux. GitHub's [Ubuntu Environments](https://github.com/actions/virtual-environments#available-environments) (`ubuntu-18.04` and newer) come with buildah installed. If you are not using these environments, or if you want to use a different version, you must first [install buildah](https://github.com/containers/buildah/blob/master/install.md).

After building your image, use [push-to-registry](https://github.com/redhat-actions/push-to-registry) to push the image and make it pullable.

## Action Inputs

<table>
  <thead>
    <tr>
      <th>Input</th>
      <th>Required</th>
      <th>Description</th>
    </tr>
  </thead>

  <tr>
    <td>image</td>
    <td>Yes</td>
    <td>Name to give the output image.</td>
  </tr>

  <tr>
    <td>tag</td>
    <td>No</td>
    <td>
      Tag to give to the output image.<br>
      Default: <code>latest</code>
    </td>
  </tr>

  <tr>
    <td>base-image</td>
    <td>No</td>
    <td>The base image to use to create the initial container. If not specified, the action will try to pick one automatically. (N.B: At this time the action is only able to auto select Java base image)</td>
  </tr>

  <tr>
    <td>dockerfiles</td>
    <td>No</td>
    <td>The list of Dockerfile paths to perform a build using docker instructions. This is a multiline input to allow multiple Dockerfiles.
    </td>
  </tr>

  <tr>
    <td>oci</td>
    <td>No</td>
    <td>
      Build the image using the OCI format, instead of the Docker format.<br>
      By default, this is <code>false</code>, because images built using the OCI format have <a href="https://github.com/docker/hub-feedback/issues/1871">issues</a> when published to Dockerhub.
    </td>
  </tr>

  <tr>
    <td>context</td>
    <td>No</td>
    <td>Path to directory to use as the build context.<br>
    Default: <code>.</code></td>
  </tr>

  <tr>
    <td>build-args</td>
    <td>No</td>
    <td>Build arguments to pass to the Docker build using <code>--build-arg</code>, if using a Dockerfile that requires ARGs.<br>
    Uses the form <code>arg_name=arg_value</code>, and separate arguments with newlines.</td>
  </tr>

  <tr>
    <td>content</td>
    <td>No</td>
    <td>The content to copy inside the container to create the final image. This is a multiline input to allow you to copy more than one file/directory.<br>
    <pre>content: |
  target/spring-petclinic-2.3.0.BUILD-SNAPSHOT.jar</pre>
    </td>
  </tr>

  <tr>
    <td>entrypoint</td>
    <td>No</td>
    <td>The entry point to set for the container. This is a multiline input; split arguments across lines.
      <pre>entrypoint: |
  java
  -jar
  spring-petclinic-2.3.0.BUILD-SNAPSHOT.jar</pre>
    </td>
  </tr>

  <tr>
    <td>port</td>
    <td>No</td>
    <td>The port to expose when running the container.</td>
  </tr>

  <tr>
    <td>workdir</td>
    <td>No</td>
    <td>The working directory to use within the container.</td>
  </tr>

  <tr>
    <td>envs</td>
    <td>No</td>
    <td>The environment variables to be set when running the container. This is a multiline input to add multiple environment variables.<br>
      <pre>
envs: |
  GOPATH=/root/buildah/go</pre>
    </td>
  </tr>
</table>

## Build Types

You can configure the `buildah` action to build your image using one or more Dockerfiles, or from scratch.

### Building using Docker

If you have been using Docker and have an existing Dockerfile, `buildah` can reuse your dockerfile.

In this case the inputs needed are `image` and `dockerfiles`. `tag` is also recommended. If your Dockerfile requires ARGs, these can be passed using `build-arg`.

```yaml
name: Build Image using Dockerfile
on: [push]

jobs:
  build:
    name: Build image
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - name: Buildah Action
      uses: redhat-actions/buildah-build@v1
      with:
        image: my-new-image
        tag: v1
        dockerfiles: |
          ./Dockerfile          
        build-args: |
          some_arg=some_value          
```

### Building from scratch

Building from scratch requires more inputs, that would normally be specified in the Dockerfile.

Do not set `dockerfiles` if you are doing a build from scratch, or a docker build will be performed, and the other inputs will be ignored.

- An output `image` name and usually a `tag`.
- `base-image`
  - In a Dockerfile, this would be the `FROM` directive.
- `content` to copy into the new image
  - In a Dockerfile, this would be `COPY` directives.
- `entrypoint` so the container knows what command to run.
  - In a Dockerfile, this would be the `ENTRYPOINT`.
- All other optional configuration inputs, such as `port`, `envs`, and `workdir`.

Example of building a Spring Boot Java app image:
```yaml
name: Build Image
on: [push]

jobs:
  build-image:
    name: Build image
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - run: mvn package

    - name: Build Image
      uses: redhat-actions/buildah-build@v1
      with:
        base-image: docker.io/fabric8/java-alpine-openjdk11-jre
        image: my-new-image
        tag: v1
        content: |
          target/spring-petclinic-2.3.0.BUILD-SNAPSHOT.jar          
        entrypoint: java -jar spring-petclinic-2.3.0.BUILD-SNAPSHOT.jar
        port: 8080
```

## Contributing

This is an open source project open to anyone. This project welcomes contributions and suggestions!

## Feedback & Questions

If you discover an issue please file a bug in [GitHub issues](https://github.com/redhat-actions/buildah/issues) and we will fix it as soon as possible.

## License

MIT, See [LICENSE](https://github.com/redhat-actions/buildah/blob/main/LICENSE.md) for more information.