Add composer-install buildpack (#2)

* Add build, detect, and integration tests

* Use 'composer check-platform-reqs' to generate an ini file for extensions

* Use "os" instead of "io/ioutil"

- https://pkg.go.dev/io/ioutil
- "As of Go 1.16, the same functionality is now provided by package io or package os, and those implementations should be preferred in new code. See the specific function documentation for details."

* Use "To(Succeed())" matcher instead of "NotTo(HaveOccurred())"

* Update README for clarity

* Add godocs and additional test coverage for PHP Version Resolver

* Clarify how "check-platform-reqs" generates a PHP INI file

* Add godoc

* Add godocs

* fix typo

* Add additional logs and integration testing for those logs

* Add additional test cases, especially for errors and logging

* Use .NotTo(HaveOccurred()) matcher when appropriate

* Increase failure cases or mark err handling as untested

- Almost all of the err handling should only occurr if there's a problem with
the layers directory

* Set layer cache flag equal to layer build flag

* Fix lint

* Remove README TODOs

Co-authored-by: Sophie Wigmore <[email protected]>

.github/workflows/approve-bot-pr.yml

@@ -53,7 +53,7 @@ jobs:
     - name: Checkout
       if: steps.human-commits.outputs.human_commits == 'false' && steps.unverified-commits.outputs.unverified_commits == 'false'
       uses: actions/checkout@v3
-
+      
     - name: Approve
       if: steps.human-commits.outputs.human_commits == 'false' && steps.unverified-commits.outputs.unverified_commits == 'false'
       uses: paketo-buildpacks/github-config/actions/pull-request/approve@main
@@ -66,4 +66,4 @@ jobs:
       run: |
         gh pr merge ${{ needs.download.outputs.pr-number }} --auto --rebase
       env:
-        GITHUB_TOKEN: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+        GITHUB_TOKEN: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}

.github/workflows/auto-merge.yml

@@ -0,0 +1,44 @@
+name: Auto-Merge
+
+on:
+  pull_request_review:
+    types:
+    - submitted
+
+jobs:
+  automerge:
+    name: Merge or Rebase
+    if: ${{ github.event.review.user.login == 'paketo-bot-reviewer' }}
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Fetch Pull Request Details
+      id: pull_request
+      env:
+        NUMBER: ${{ github.event.pull_request.number }}
+        GITHUB_TOKEN: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+      run: |
+        payload="$(
+          curl "https://api.github.com/repos/${GITHUB_REPOSITORY}/pulls/${NUMBER}" \
+            --silent \
+            --location \
+            --header "Authorization: token ${GITHUB_TOKEN}"
+        )"
+
+        echo "::set-output name=mergeable_state::$(echo "${payload}" | jq -r -c .mergeable_state)"
+
+    - name: Merge
+      if: ${{ steps.pull_request.outputs.mergeable_state == 'clean' || steps.pull_request.outputs.mergeable_state == 'unstable' }}
+      uses: paketo-buildpacks/github-config/actions/pull-request/merge@main
+      with:
+        token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+        number: ${{ github.event.pull_request.number }}
+
+    - name: Rebase
+      if: ${{ steps.pull_request.outputs.mergeable_state == 'behind' }}
+      uses: paketo-buildpacks/github-config/actions/pull-request/rebase@main
+      with:
+        token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+        number: ${{ github.event.pull_request.number }}

.github/workflows/check-pr-labels.yml

@@ -0,0 +1,24 @@
+name: Validate PR Labels
+on:
+  pull_request:
+    branches:
+    - main
+    types:
+    - synchronize
+    - opened
+    - reopened
+    - labeled
+    - unlabeled
+
+concurrency: pr_labels
+
+jobs:
+  semver:
+    name: Ensure Minimal Semver Labels
+    runs-on: ubuntu-latest
+    steps:
+    - uses: mheap/github-action-required-labels@v1
+      with:
+        count: 1
+        labels: semver:major, semver:minor, semver:patch
+        mode: exactly

.gitignore

@@ -0,0 +1,3 @@
+.idea/
+build/
+.bin/

README.md

@@ -1 +1,141 @@
-# Paketo Composer Install Buildpack
+# PHP Composer Install Cloud Native Buildpack
+
+This buildpack runs the [composer](https://getcomposer.org/) command `composer install`  to download project dependencies.
+It requires both `composer` and `php` on the path (see [requires](#requires)).
+
+A usage example can be found in the
+[`samples` repository under the `php/composer` directory](https://github.com/paketo-buildpacks/samples/tree/main/php/composer).
+
+## Detection
+
+Will add these requires/provisions to the build plan if and only if a `composer.json` file is found.
+
+### Requires:
+
+- `composer`
+- `php`
+
+### Provides:
+
+- `composer-packages`
+
+## Build
+
+Will run `composer install` in the project workspace to download project dependencies.
+The dependencies will be placed in a new layer and symlinked into the workspace at the 
+location specified by `COMPOSER_VENDOR_DIR`, which defaults to `vendor`.
+
+If dependencies are needed for Composer install scripts, use `BP_COMPOSER_INSTALL_GLOBAL`
+to specify which dependencies to install. 
+
+Use of a `composer.lock` file will enable caching of the downloaded dependencies, such that
+subsequent builds with the same `composer.lock` file will not need to run `composer install` again.
+
+## Integration
+
+The PHP Composer CNB provides `composer-packages` as a dependency. Downstream buildpacks
+can require that dependency by generating a [Build Plan
+TOML](https://github.com/buildpacks/spec/blob/master/buildpack.md#build-plan-toml)
+file that looks like the following:
+
+```toml
+[[requires]]
+
+    # The PHP Composer Install provision is named `composer-packages`.
+    # This value is considered part of the public API for the buildpack and will not 
+    # change without a plan for deprecation.
+    name = "composer-packages"
+
+    # The PHP Composer Install buildpack requires some additional metadata options.
+    # If neither metadata.build or metadata.launch is provided, this buidpack will contribute
+    # an ignored layer
+    [requires.metadata]
+
+        # Setting the build flag to true will ensure that packages installed by running
+        # `composer install` are available for subsequent buildpacks during their launch phase
+        launch = true
+
+        # Setting the build flag to true will ensure that packages installed by running
+        # `composer install` are available for subsequent buildpacks during their build phase
+        build = true
+```
+## Logging Configurations
+
+To configure the level of log output from the **buildpack itself**, set the
+`BP_LOG_LEVEL` environment variable at build time either directly or through
+a [`project.toml` file](https://github.com/buildpacks/spec/blob/main/extensions/project-descriptor.md)
+If no value is set, the default value of `INFO` will be used.
+
+The options for this setting are:
+- `INFO`: (Default) log information about the detection and build processes
+- `DEBUG`: log debugging information about the detection and build processes
+
+```shell
+pack build my-app --env BP_LOG_LEVEL=DEBUG
+```
+
+## Usage
+
+To package this buildpack for consumption
+
+```
+$ ./scripts/package.sh -v <version>
+```
+
+This builds the buildpack's Go source using `GOOS=linux` by default. You can supply another value as the first argument to package.sh.
+
+## Configuration
+
+### `COMPOSER`
+
+The `COMPOSER` variable allows you to specify the filename of `composer.json`.
+When set, this buildpack will use this location instead of `composer.json` in the detection phase.
+This value must be relative to the project root.
+
+For more information, please reference the [composer docs](https://getcomposer.org/doc/03-cli.md#composer).
+
+```shell
+COMPOSER=somewhere/composer-other.json
+```
+
+### `BP_COMPOSER_INSTALL_OPTIONS`
+
+Use `BP_COMPOSER_INSTALL_OPTIONS` to specify options for the Composer [install command](https://getcomposer.org/doc/03-cli.md#install-i).
+This buildpacks will always prepend `--no-progress` to the list of install options.
+The default is `--no-dev`.
+
+Note: `BP_COMPOSER_INSTALL_OPTIONS` will be parsed using the [shellwords library](https://github.com/mattn/go-shellwords).
+
+```shell
+# Note that env variables will typically be provided to this buildpack using `pack build -e`
+BP_COMPOSER_INSTALL_OPTIONS=--prefer-install --ignore-platform-reqs
+# will result in an installation command of `composer install --no-progress --prefer-install --ignore-platform-reqs`
+BP_COMPOSER_INSTALL_OPTIONS= # Note that this is set to empty
+# will result in an installation command of `composer install --no-progress`
+unset BP_COMPOSER_INSTALL_OPTIONS
+# will result in an installation command of `composer install --no-progress --no-dev`
+```
+
+### `BP_COMPOSER_INSTALL_GLOBAL`
+
+Use `BP_COMPOSER_INSTALL_GLOBAL` to specify packages required by Composer scripts.
+These will be installed using `composer global require`.
+These packages will not be available to the application.
+
+```shell
+BP_COMPOSER_INSTALL_GLOBAL="friendsofphp/php-cs-fixer squizlabs/php_codesniffer=*"
+```
+
+### Other environment variables
+
+Other environment variables used by Composer may be passed in to configure Composer behavior. 
+See the [full list here](https://getcomposer.org/doc/03-cli.md#environment-variables).
+A few examples are shown here.
+
+- `COMPOSER_VENDOR_DIR`:
+Used to make Composer install the dependencies into a directory other than `vendor`. 
+This value must be underneath the project root.
+
+- `COMPOSER_AUTH`:
+Used to set up authentication, for example to add a GitHub OAuth token to increase the 
+default rate limit.