GitHub Action to display Git changes and fail a build

LICENSE

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+MIT License
+
+Copyright (c) 2022 Jonathan Ballet
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Git changes action
+
+This GitHub Action:
+
+* Show pending changes in a Git repository: uncommited files and pending
+  modifications.
+
+  ![untracked files](/doc/status.png)
+
+* Fail the step if there are any pending changes.
+
+  ![modified files](/doc/diff.png)
+
+This can be used to verify that the content of a Git repository didn't change
+after a set of steps.
+
+To use this GitHub Action:
+
+```yaml
+      - name: Check Git changes
+        uses: camunda-cloud/git-changes-action@v1
+```

action.yml

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+name: Git changes verifier
+description: |
+  Display changes from Git and fail the build if there are any changes pending.
+
+branding:
+  icon: alert-triangle
+  color: red
+
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      name: Find changes
+      run: ${{ github.action_path }}/git-changes.sh

git-changes.sh

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+#!/bin/bash
+
+set -euo pipefail
+
+output="$(git -c color.status=always status --short)"
+
+if [ -n "$output" ]; then
+  echo "== git status =="
+  echo -e "$output"
+  echo "================"
+fi
+
+git diff --color=always --exit-code
+
+if [ -n "$output" ]; then
+  echo
+  echo -e "\e[31;1mThere are pending changes!\e[0m"
+  exit 1
+fi