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irfansofyana committed Jan 2, 2025
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# Dev Container Features: Self Authoring Template
# Dev Container Features Collection

> This repo provides a starting point and example for creating your own custom [dev container Features](https://containers.dev/implementors/features/), hosted for free on GitHub Container Registry. The example in this repository follows the [dev container Feature distribution specification](https://containers.dev/implementors/features-distribution/).
>
> To provide feedback to the specification, please leave a comment [on spec issue #70](https://github.com/devcontainers/spec/issues/70). For more broad feedback regarding dev container Features, please see [spec issue #61](https://github.com/devcontainers/spec/issues/61).
This repository contains my personal collection of [Dev Container Features](https://containers.dev/implementors/features/) that I've built and regularly use in my daily workflow as a software engineer. These features are designed to streamline development environment setup and enhance productivity across different projects.

## Example Contents
## Available Features

This repository contains a _collection_ of two Features - `hello` and `color`. These Features serve as simple feature implementations. Each sub-section below shows a sample `devcontainer.json` alongside example usage of the Feature.
### `kcat-apt`

### `hello`

Running `hello` inside the built container will print the greeting provided to it via its `greeting` option.
A Kafka command line utility using kcat (formerly kafkacat). This feature is specifically designed for Debian/Ubuntu-based containers.

```jsonc
{
"image": "mcr.microsoft.com/devcontainers/base:ubuntu",
"features": {
"ghcr.io/devcontainers/feature-starter/hello:1": {
"greeting": "Hello"
"ghcr.io/irfanputra/devcontainer-features/kcat-apt:1": {
"version": "latest"
}
}
}
```

```bash
$ hello
#### Options

Hello, user.
```
| Option | Type | Default | Description |
|--------|------|---------|-------------|
| version | string | "latest" | Select version of kcat (kafkacat) to install. Use distribution version format (e.g., '1.7.0-1'). |

### `color`
## Repo Structure

Running `color` inside the built container will print your favorite color to standard out.

```jsonc
{
"image": "mcr.microsoft.com/devcontainers/base:ubuntu",
"features": {
"ghcr.io/devcontainers/feature-starter/color:1": {
"favorite": "green"
}
}
}
```

```bash
$ color

my favorite color is green
```

## Repo and Feature Structure

Similar to the [`devcontainers/features`](https://github.com/devcontainers/features) repo, this repository has a `src` folder. Each Feature has its own sub-folder, containing at least a `devcontainer-feature.json` and an entrypoint script `install.sh`.
This repository follows the standard dev container Feature structure:

```
├── src
│ ├── hello
│ │ ├── devcontainer-feature.json
│ │ └── install.sh
│ ├── color
│ │ ├── devcontainer-feature.json
│ │ └── install.sh
| ├── ...
│ │ ├── devcontainer-feature.json
│ │ └── install.sh
...
```

An [implementing tool](https://containers.dev/supporting#tools) will composite [the documented dev container properties](https://containers.dev/implementors/features/#devcontainer-feature-json-properties) from the feature's `devcontainer-feature.json` file, and execute in the `install.sh` entrypoint script in the container during build time. Implementing tools are also free to process attributes under the `customizations` property as desired.

### Options

All available options for a Feature should be declared in the `devcontainer-feature.json`. The syntax for the `options` property can be found in the [devcontainer Feature json properties reference](https://containers.dev/implementors/features/#devcontainer-feature-json-properties).

For example, the `color` feature provides an enum of three possible options (`red`, `gold`, `green`). If no option is provided in a user's `devcontainer.json`, the value is set to "red".

```jsonc
{
// ...
"options": {
"favorite": {
"type": "string",
"enum": [
"red",
"gold",
"green"
],
"default": "red",
"description": "Choose your favorite color."
}
}
}
```

Options are exported as Feature-scoped environment variables. The option name is captialized and sanitized according to [option resolution](https://containers.dev/implementors/features/#option-resolution).

```bash
#!/bin/bash

echo "Activating feature 'color'"
echo "The provided favorite color is: ${FAVORITE}"

...
│ └── kcat-apt
│ ├── devcontainer-feature.json # Feature metadata and options
│ ├── install.sh # Installation script
│ └── README.md # Feature-specific documentation
├── test # Test files
└── README.md # This file
```

## Distributing Features

### Versioning

Features are individually versioned by the `version` attribute in a Feature's `devcontainer-feature.json`. Features are versioned according to the semver specification. More details can be found in [the dev container Feature specification](https://containers.dev/implementors/features/#versioning).
## Contributing

### Publishing
1. Fork the repository
2. Create a new feature directory under `src/`
3. Add the required files:
- `devcontainer-feature.json`
- `install.sh`
- `README.md` (optional)
4. Add tests under the `test/` directory
5. Submit a pull request

> NOTE: The Distribution spec can be [found here](https://containers.dev/implementors/features-distribution/).
>
> While any registry [implementing the OCI Distribution spec](https://github.com/opencontainers/distribution-spec) can be used, this template will leverage GHCR (GitHub Container Registry) as the backing registry.
## License

Features are meant to be easily sharable units of dev container configuration and installation code.

This repo contains a **GitHub Action** [workflow](.github/workflows/release.yaml) that will publish each Feature to GHCR.

*Allow GitHub Actions to create and approve pull requests* should be enabled in the repository's `Settings > Actions > General > Workflow permissions` for auto generation of `src/<feature>/README.md` per Feature (which merges any existing `src/<feature>/NOTES.md`).

By default, each Feature will be prefixed with the `<owner/<repo>` namespace. For example, the two Features in this repository can be referenced in a `devcontainer.json` with:

```
ghcr.io/devcontainers/feature-starter/color:1
ghcr.io/devcontainers/feature-starter/hello:1
```

The provided GitHub Action will also publish a third "metadata" package with just the namespace, eg: `ghcr.io/devcontainers/feature-starter`. This contains information useful for tools aiding in Feature discovery.

'`devcontainers/feature-starter`' is known as the feature collection namespace.

### Marking Feature Public

Note that by default, GHCR packages are marked as `private`. To stay within the free tier, Features need to be marked as `public`.

This can be done by navigating to the Feature's "package settings" page in GHCR, and setting the visibility to 'public`. The URL may look something like:

```
https://github.com/users/<owner>/packages/container/<repo>%2F<featureName>/settings
```

<img width="669" alt="image" src="https://user-images.githubusercontent.com/23246594/185244705-232cf86a-bd05-43cb-9c25-07b45b3f4b04.png">

### Adding Features to the Index

If you'd like your Features to appear in our [public index](https://containers.dev/features) so that other community members can find them, you can do the following:

* Go to [github.com/devcontainers/devcontainers.github.io](https://github.com/devcontainers/devcontainers.github.io)
* This is the GitHub repo backing the [containers.dev](https://containers.dev/) spec site
* Open a PR to modify the [collection-index.yml](https://github.com/devcontainers/devcontainers.github.io/blob/gh-pages/_data/collection-index.yml) file

This index is from where [supporting tools](https://containers.dev/supporting) like [VS Code Dev Containers](https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.remote-containers) and [GitHub Codespaces](https://github.com/features/codespaces) surface Features for their dev container creation UI.

#### Using private Features in Codespaces

For any Features hosted in GHCR that are kept private, the `GITHUB_TOKEN` access token in your environment will need to have `package:read` and `contents:read` for the associated repository.

Many implementing tools use a broadly scoped access token and will work automatically. GitHub Codespaces uses repo-scoped tokens, and therefore you'll need to add the permissions in `devcontainer.json`

An example `devcontainer.json` can be found below.

```jsonc
{
"image": "mcr.microsoft.com/devcontainers/base:ubuntu",
"features": {
"ghcr.io/my-org/private-features/hello:1": {
"greeting": "Hello"
}
},
"customizations": {
"codespaces": {
"repositories": {
"my-org/private-features": {
"permissions": {
"packages": "read",
"contents": "read"
}
}
}
}
}
}
```
This project is licensed under the terms specified in the [LICENSE](LICENSE) file.

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