asdf/docs/plugins-create.md

## What's in a Plugin

A plugin is a git repo, with a couple executable scripts, to support versioning another language or tool. These scripts are run when `list-all`, `install` or `uninstall` commands are run. You can set or unset env vars and do anything required to setup the environment for the tool.

## Required Scripts

- `bin/list-all` - lists all installable versions
- `bin/install` - installs the specified version

All scripts except `bin/list-all` will have access to the following env vars to act upon:

- `ASDF_INSTALL_TYPE` - `version` or `ref`
- `ASDF_INSTALL_VERSION` - if `ASDF_INSTALL_TYPE` is `version` then this will be the version number. Else it will be the git ref that is passed. Might point to a tag/commit/branch on the repo.
- `ASDF_INSTALL_PATH` - the dir where the it _has been_ installed (or _should_ be installed in case of the `bin/install` script)

These additional environment variables the `bin/install` script will also have accesss to:

- `ASDF_CONCURRENCY` - the number of cores to use when compiling the source code. Useful for setting `make -j`.

#### bin/list-all

Must print a string with a space-separated list of versions. Example output would be the following:

```
1.0.1 1.0.2 1.3.0 1.4
```

Note that the newest version should be listed last so it appears closer to the user's prompt. This is helpful since the `list-all` command prints each version on it's own line. If there are many versions it's possible the early versions will be off screen.

If versions are being pulled from releases page on a website it's recommended to not sort the versions if at all possible. Often the versions are already in the correct order or, in reverse order, in which case something like `tac` should suffice. If you must sort versions manually you cannot rely on `sort -V` since it is not supported on OSX. An alternate sort function [like this is a better choice](https://github.com/vic/asdf-idris/blob/master/bin/list-all#L6).

#### bin/install

This script should install the version, in the path mentioned in `ASDF_INSTALL_PATH`.

The install script should exit with a status of `0` when the installation is successful. If the installation fails the script should exit with any non-zero exit status.

If possible the script should only place files in the `ASDF_INSTALL_PATH` directory once the build and installation of the tool is deemed successful by the install script. asdf [checks for the existence](https://github.com/asdf-vm/asdf/blob/242d132afbf710fe3c7ec23c68cec7bdd2c78ab5/lib/utils.sh#L44) of the `ASDF_INSTALL_PATH` directory in order to determine if that version of the tool is installed. If the `ASDF_INSTALL_PATH` directory is populated at the beginning of the installation process other asdf commands run in other terminals during the installation may consider that version of the tool installed, even when it is not fully installed.

## Optional Scripts

#### bin/list-bin-paths

List executables for the specified version of the tool. Must print a string with a space-separated list of dir paths that contain executables. The paths must be relative to the install path passed. Example output would be:

```
bin tools veggies
```

This will instruct asdf to create shims for the files in `<install-path>/bin`, `<install-path>/tools` and `<install-path>/veggies`

If this script is not specified, asdf will look for the `bin` dir in an installation and create shims for those.

#### bin/exec-env

Setup the env to run the binaries in the package.

#### bin/exec-path

Get the executable path for the specified version of the tool. Must print a string with the relative executable path. This allows the plugin to conditionally override the shim's specified executable path, otherwise return the default path specified by the shim.

```
Usage:
  plugin/bin/exec-path <install-path> <command> <executable-path>

Example Call:
  ~/.asdf/plugins/foo/bin/exec-path "~/.asdf/installs/foo/1.0" "foo" "bin/foo"

Output:
  bin/foox
```

#### bin/uninstall

Uninstalls a specific version of a tool.

#### bin/list-legacy-filenames

Register additional setter files for this plugin. Must print a string with a space-separated list of filenames.

```
.ruby-version .rvmrc
```

Note: This will only apply for users who have enabled the `legacy_version_file` option in their `~/.asdfrc`.

#### bin/parse-legacy-file

This can be used to further parse the legacy file found by asdf. If `parse-legacy-file` isn't implemented, asdf will simply cat the file to determine the version. The script will be passed the file path as its first argument.

## Extension commands for asdf CLI.

It's possible for plugins to define new asdf commands by providing `bin/command*` scripts or executables that will
be callable using the asdf command line interface by using the plugin name as a subcommand.

For example, suppose a `foo` plugin has:

```shell
foo/
  bin/
    command
    command-bat
    command-bat-man
    command-help
```

Users can now execute

```shell
$ asdf foo         # same as running `$ASDF_DATA_DIR/plugins/foo/bin/command`
$ asdf foo bar     # same as running `$ASDF_DATA_DIR/plugins/foo/bin/command bar`
$ asdf foo help    # same as running `$ASDF_DATA_DIR/plugins/foo/bin/command-help`
$ asdf foo bat man # same as running `$ASDF_DATA_DIR/plugins/foo/bin/command-bat-man`
$ asdf foo bat baz # same as running `$ASDF_DATA_DIR/plugins/foo/bin/command-bat baz`
```

Plugin authors can use this feature to provide utilities related to their tools,
or even create plugins that are just new command extensions for asdf itself.

When `command*` files exists but have no executable bit set, they are considered to be
bash scripts and will be sourced having all the functions from `$ASDF_DIR/lib/utils.sh`
available. Also, the `$ASDF_CMD_FILE` resolves to the full path of the file being sourced.
If the executable bit is set, they are just executed and replace the asdf execution.

A good example of this feature is for plugins like `nodejs`, where people must import the release team keyring before
installing a nodejs version. Authors can provide a handy extension command for this without users
having to know where exactly is the plugin was installed.

If your plugin provides an asdf extension command, be sure to mention about it on your plugin's README.

## Custom shim templates

**PLEASE use this feature only if absolutely required**

asdf allows custom shim templates. For an executable called `foo`, if there's a `shims/foo` file in the plugin, then asdf will copy that file instead of using it's standard shim template.

This must be used wisely. For now AFAIK, it's only being used in the Elixir plugin, because an executable is also read as an Elixir file apart from just being an executable. Which makes it not possible to use the standard bash shim.

## Testing plugins

`asdf` contains the `plugin-test` command to test your plugin. You can use it as follows

```sh
asdf plugin test <plugin-name> <plugin-url> [--asdf-tool-version <version>] [--asdf-plugin-gitref <git-ref>] [test-command*]
```

Only the two first arguments are required.
If __version_ is specified, the tool will be installed with that specific version. Defaults to whatever returns `asdf latest <plugin-name>`.
If _git-ref_ is specified, the plugin itself is checked out at that commit/branch/tag, useful for testing a pull-request on your plugin's CI.

Rest arguments are considered the command to execute to ensure the installed tool works correctly.
Normally it would be something that takes `--version` or `--help`.
For example, to test the NodeJS plugin, we could run

```sh
asdf plugin test nodejs https://github.com/asdf-vm/asdf-nodejs.git node --version
```

We strongly recommend you test your plugin on a CI environment and make sure it works on both Linux and OSX.

#### Example Github Action

The [asdf-vm/actions](https://github.com/asdf-vm/actions) repo provides a GitHub Action for testing your plugins hosted on github.

```yaml
steps:
  - name: asdf_plugin_test
    uses: asdf-vm/actions/plugin-test@v1.0.0
    with:
      command: "my_tool --version"
    env:
      GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }} # automatically provided
```

#### Example TravisCI config

Here is a sample `.travis.yml` file, customize it to your needs

```yaml
language: c
script: asdf plugin test nodejs $TRAVIS_BUILD_DIR 'node --version'
before_script:
  - git clone https://github.com/asdf-vm/asdf.git asdf
  - . asdf/asdf.sh
os:
  - linux
  - osx
```

Note:
When using another CI, you will need to check what variable maps to the repo path.

You also have the option to pass a relative path to `plugin-test`.

For example, if the test script is ran in the repo directory: `asdf plugin test nodejs . 'node --version'`.

## GitHub API Rate Limiting

If your plugin's `list-all` depends on accessing the GitHub API, make sure you provide an Authorization token when accessing it, otherwise your tests might fail due to rate limiting.

To do so, create a [new personal token](https://github.com/settings/tokens/new) with only `public_repo` access.

Then on your travis.ci build settings add a _secure_ environment variable for it named something like `GITHUB_API_TOKEN`. And _DO NOT_ EVER publish your token in your code.

Finally, add something like the following to `bin/list-all`

```shell
cmd="curl -s"
if [ -n "$GITHUB_API_TOKEN" ]; then
 cmd="$cmd -H 'Authorization: token $GITHUB_API_TOKEN'"
fi

cmd="$cmd $releases_path"
```

## Submitting plugins to the official plugins repository

`asdf` can easily install plugins by specifying the plugin repository url, e.g. `plugin add my-plugin https://github.com/user/asdf-my-plugin.git`.

To make it easier on your users, you can add your plugin to the official plugins repository to have your plugin listed and easily installable using a shorter command, e.g. `asdf plugin add my-plugin`.

Follow the instruction at the plugins repository: [asdf-vm/asdf-plugins](https://github.com/asdf-vm/asdf-plugins).