Replace Python script with Bash script for version retrieval

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 Red Matter and contributors
+
+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

@@ -1,23 +1,178 @@
 # git-version
 
-Module for retrieving versions from the git repo from which the parent module is running.
+Terraform module for retrieving version information from the Git repository in which the parent module is running. This module uses `git describe` to generate semantic version strings based on Git tags, commit history, and working tree state.
 
-## Overrides
+> **Windows Users:** See the [Windows Compatibility Guide](WINDOWS.md) for detailed setup instructions and troubleshooting.
 
-The version returned can be overridden via the environment and via a passed in override variable.
+## Features
 
-### Environment
+- **Zero external dependencies** - Only requires Bash (3.2+) and Git
+- **Cross-platform compatible** - Works on Linux, macOS, and other Unix-like systems
+- **Flexible version override system** - Support for environment variables and explicit overrides
+- **CI/CD friendly** - Handles scenarios where Git may not be available during apply-time
 
-By default, if the `TF_MODULE_VERSION` environment variable is set, this module will return the value of that variable
-instead of using Git to determine a version.
+## Dependencies
 
-The environment variable to check can be changed by setting the `version_environment_variable` variable.
+This module requires the following to be available in the execution environment:
 
-### Override variable
+| Dependency | Minimum Version | Purpose | Notes |
+|------------|-----------------|---------|-------|
+| **Terraform** | >= 0.12.0 | Infrastructure as Code runtime | Required |
+| **Bash** | >= 3.2 | Shell script execution | Compatible with macOS default bash |
+| **Git** | Any | Version control system | Must be available in PATH unless using overrides |
 
-The `version_override` variable defaults to `null`, but if set will be returned.
-In this case neither the Git repo nor the environment will be checked.
+### Platform Compatibility
 
-This can be useful as a way to allow parent modules to override the version via a variable without needing to implement
-logic of their own to optionally use the module depending on the status of their override variable.
-Instead, they can just pass the override variable in and if it's `null` then it will be ignored.
+- ✅ **Linux** - All distributions with bash and git
+- ✅ **macOS** - Compatible with default bash 3.2 (no Homebrew updates required)
+- ✅ **Windows** - Git Bash, WSL, or Cygwin environments ([detailed Windows guide](WINDOWS.md))
+- ✅ **CI/CD** - Works with environment variable overrides when Git is unavailable
+
+**Windows Users:** Git Bash is automatically included with Git for Windows. No additional installation required. See the [Windows Compatibility Guide](WINDOWS.md) for details.
+
+## Usage
+
+### Basic Usage
+
+```hcl
+module "version" {
+  source = "path/to/git-version"
+}
+
+output "current_version" {
+  value = module.version.version
+}
+```
+
+### With Custom Environment Variable
+
+```hcl
+module "version" {
+  source = "path/to/git-version"
+
+  version_environment_variable = "MY_CUSTOM_VERSION_VAR"
+}
+```
+
+### With Explicit Override
+
+```hcl
+module "version" {
+  source = "path/to/git-version"
+
+  version_override = "1.2.3-custom"
+}
+```
+
+## Version Resolution
+
+The module resolves versions using the following priority order (highest to lowest):
+
+### 1. Explicit Override (Highest Priority)
+
+The `version_override` variable directly sets the version, bypassing both environment variables and Git.
+
+```hcl
+version_override = "2.0.0-rc1"
+```
+
+**Use case:** Parent modules that need to conditionally override versions without implementing their own logic.
+
+### 2. Environment Variable Override
+
+By default, the `TF_MODULE_VERSION` environment variable is checked. If set, its value is returned instead of querying Git.
+
+```bash
+export TF_MODULE_VERSION=1.5.0
+terraform plan
+```
+
+The environment variable name can be customized:
+
+```hcl
+version_environment_variable = "DEPLOYMENT_VERSION"
+```
+
+**Use case:** CI/CD pipelines where Git may not be available during `terraform apply`, or when you want to pin a specific version for a deployment.
+
+### 3. Git Describe (Default Fallback)
+
+If no overrides are set, the module executes:
+
+```bash
+git describe --tags --long --dirty --always
+```
+
+This produces version strings like:
+
+- `1.2.3-0-ga1b2c3d` - On a tagged commit
+- `1.2.3-5-ga1b2c3d` - 5 commits after tag 1.2.3
+- `1.2.3-5-ga1b2c3d-dirty` - Same as above with uncommitted changes
+- `a1b2c3d` - No tags found (falls back to commit hash)
+
+**Use case:** Standard development workflow where Git history accurately reflects versioning.
+
+## Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|------|---------|----------|
+| `version_environment_variable` | Name of the environment variable to check for version override | `string` | `"TF_MODULE_VERSION"` | No |
+| `version_override` | Explicit version string to return (bypasses Git and environment) | `string` | `null` | No |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| `version` | The resolved version string from Git, environment, or override |
+
+## How It Works
+
+The module uses Terraform's `external` data source to execute a bash script ([git_describe.sh](git_describe.sh)) that:
+
+1. Checks if the specified environment variable contains a version
+2. If not, executes `git describe --tags --long --dirty --always`
+3. Returns the version as JSON: `{"version": "..."}`
+4. Falls back to `"UNKNOWN"` if Git command fails
+
+## CI/CD Integration
+
+### GitHub Actions Example
+
+```yaml
+- name: Terraform Plan
+  env:
+    TF_MODULE_VERSION: ${{ github.ref_name }}
+  run: terraform plan
+```
+
+### GitLab CI Example
+
+```yaml
+terraform:
+  variables:
+    TF_MODULE_VERSION: $CI_COMMIT_TAG
+  script:
+    - terraform apply
+```
+
+### Jenkins Example
+
+```groovy
+environment {
+    TF_MODULE_VERSION = "${env.GIT_TAG}"
+}
+```
+
+## Migration Notes
+
+**Version 1.2.0+**: Removed Python dependency in favor of Bash. The Python script (`git_describe.py`) is no longer used or required. If you have older versions of this module pinned, no changes are needed - the bash implementation produces identical output.
+
+**For Windows users:** Git Bash (included with Git for Windows) provides all required functionality. No additional setup needed beyond Git, which is already required for version control. See [WINDOWS.md](WINDOWS.md) for comprehensive Windows compatibility information, troubleshooting, and FAQs.
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+
+## Contributing
+
+When modifying the bash script, ensure compatibility with bash 3.2+ for macOS support. Test on both modern Linux (bash 5.x) and macOS (bash 3.2) before submitting changes.