Add Galaxy import workflow (#754)

* Add Galaxy import workflow.

* A dependency of galaxy-importer does not work on Python 3.12.

* Make yamllint happy.

(cherry picked from commit 5adac52)

.github/workflows/import-galaxy.yml

@@ -0,0 +1,130 @@
+---
+# Copyright (c) Ansible Project
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+name: import-galaxy
+'on':
+  # Run CI against all pushes (direct commits, also merged PRs) to main, and all Pull Requests
+  push:
+    branches:
+      - main
+      - stable-*
+  pull_request:
+
+jobs:
+  build-collection:
+    name: Build collection artifact
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+        with:
+          path: ./checkout
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+
+      - name: Install ansible-core devel
+        run: pip install https://github.com/ansible/ansible/archive/devel.tar.gz --disable-pip-version-check
+
+      - name: Make sure galaxy.yml has version entry
+        shell: python
+        id: collection-metadata
+        run: |
+          import os
+          import yaml
+
+          def set_output(name, value):
+              with open(os.environ['GITHUB_OUTPUT'], 'a', encoding='utf-8') as f:
+                  f.write(f'{name}={value}{os.linesep}')
+
+          # Make sure galaxy.yml contains a version
+          with open('galaxy.yml', 'rb') as f:
+              data = yaml.safe_load(f) ;
+          data['version'] = data.get('version') or '0.0.1'
+          with open('galaxy.yml', 'w', encoding='utf-8') as f:
+              f.write(yaml.dump(data))
+
+          # Create Galaxy requirements file
+          if data.get('dependencies'):
+              reqs = dict(collections=[])
+              for collection, version in sorted(data['dependencies'].items()):
+                  reqs['collections'].append(dict(
+                      name=collection,
+                      source='https://galaxy.ansible.com',
+                      version=version,
+                  ))
+              with open('../requirements.yml', 'w', encoding='utf-8') as f:
+                  f.write(yaml.dump(reqs))
+
+          # Extract namespace and collection name
+          set_output('name', data['name'])
+          set_output('namespace', data['namespace'])
+          set_output('version', data['version'])
+          set_output('filename', f"{data['namespace']}-{data['name']}-{data['version']}.tar.gz")
+        working-directory: ./checkout
+
+      - name: Build collection
+        run: ansible-galaxy collection build
+        working-directory: ./checkout
+
+      - name: Copy artifact into subdirectory
+        shell: bash
+        run: |
+          set -e
+          mkdir artifact
+          mv checkout/${{ steps.collection-metadata.outputs.filename }} artifact/
+          if [ -f requirements.yml ]; then
+            mv requirements.yml artifact/
+          fi
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: collection-build-${{ github.sha }}
+          path: ./artifact/
+
+  import-galaxy:
+    name: Import artifact with Galaxy importer
+    runs-on: ubuntu-latest
+    needs:
+      - build-collection
+    steps:
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          # Currently requirements-parser is incompatible with Python 3.12
+          # (https://github.com/madpah/requirements-parser/issues/88), so we
+          # have to stick to Python 3.11 for now...
+          python-version: '3.11'
+
+      - name: Install ansible-core devel
+        run: pip install https://github.com/ansible/ansible/archive/devel.tar.gz --disable-pip-version-check
+
+      - name: Install galaxy-importer
+        run: pip install galaxy-importer --disable-pip-version-check
+
+      - name: Download artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: collection-build-${{ github.sha }}
+
+      - name: List files
+        shell: bash
+        run: |
+          ls -la
+
+      - name: Install collection dependencies
+        shell: bash
+        run: |
+          if [ -f requirements.yml ]; then
+            ansible-galaxy collection install --pre --requirements-file requirements.yml
+          else
+            echo "Collection has no dependencies."
+          fi
+
+      - name: Run Galaxy importer
+        run: python -m galaxy_importer.main *-*-*.tar.gz