rust-build-release action: bin-name should auto-detect binary instead of defaulting to test fixture

[coderabbitai]

Problem

The rust-build-release shared action has a bin-name input that defaults to rust-toy-app (a test fixture). When workflows do not explicitly pass the bin-name input, the action uses this default value and fails to find the actual binary produced by the build.

Desired Behaviour

The action should:

• Raise an error when multiple binaries exist with no default specified
• Automatically discover a default binary where possible (e.g., when only one binary target exists)
• Not use a test fixture as the default value

Context

Reported by @leynos in PR #226
Related PR: #226

[traycerai]

Plan

Observations

The rust-build-release action currently defaults the bin-name input to rust-toy-app, a test fixture. This causes failures when workflows don't explicitly provide the binary name. The codebase already has cargo_utils.py with a get_bin_name() function that can extract binary names from Cargo.toml by checking [[bin]] entries or falling back to [package].name. The action's "Stage artefacts" step uses bin-name to locate the built binary and man page, but there's no validation for multiple binaries or auto-detection logic.

Approach

The solution will modify the action to auto-detect the binary name from Cargo.toml when not explicitly provided. This involves: (1) removing the hardcoded default from action.yml, (2) creating a new Python script to resolve the binary name using existing cargo_utils.py functions, (3) adding validation to raise errors when multiple binaries exist without an explicit choice, and (4) updating the action workflow to call this script before the "Stage artefacts" step. This approach leverages existing utilities and maintains consistency with the repository's Python scripting patterns.

Implementation Steps

1. Update Action Input Definition

File: file:.github/actions/rust-build-release/action.yml

• Remove the default value rust-toy-app from the bin-name input (line 18)
• Change required: false to keep it optional
• Update the description to clarify auto-detection behavior: "Name of the binary produced by the build. If not specified, will be auto-detected from Cargo.toml (requires exactly one binary target)"

2. Create Binary Name Resolution Script

File: file:.github/actions/rust-build-release/src/resolve_bin_name.py (new file)

Create a new Python script with PEP 723 metadata:

• Dependencies: ["plumbum", "syspath-hack>=0.4.0,<0.5.0", "typer"]
• Import cargo_utils functions: read_manifest, get_bin_name
• Accept CLI arguments: --manifest-path (path to Cargo.toml), --bin-name (optional override)
• Logic flow:
  • If --bin-name is provided, validate it's non-empty and return it
  • Otherwise, read the manifest using read_manifest()
  • Check if [[bin]] array exists and has multiple entries
  • If multiple binaries exist, raise error: "Multiple binary targets found in Cargo.toml. Please specify bin-name input explicitly."
  • Otherwise, use get_bin_name() to extract the binary name
  • Print the resolved binary name to stdout for capture
• Use typer for CLI interface following the pattern in file:.github/actions/rust-build-release/src/action_setup.py
• Include proper error handling with GitHub Actions error annotations (::error::)

3. Add Binary Name Resolution Step to Action

File: file:.github/actions/rust-build-release/action.yml

Insert a new step after "Build release" (after line 65) and before "Stage artefacts":

• Name: "Resolve binary name"
• Condition: if: contains(inputs.target, 'unknown-linux-') || contains(inputs.target, 'unknown-illumos')
• Shell: bash
• Working directory: ${{ inputs.project-dir }}
• Script logic:
  • Call uv run --script "$GITHUB_ACTION_PATH/src/resolve_bin_name.py" with --manifest-path "${{ inputs.manifest-path }}" and conditionally --bin-name "${{ inputs.bin-name }}" if provided
  • Capture output to RESOLVED_BIN_NAME environment variable
  • Export to $GITHUB_ENV for subsequent steps
  • Handle empty inputs.bin-name gracefully (only pass flag if non-empty)

4. Update Stage Artefacts Step

File: file:.github/actions/rust-build-release/action.yml

Modify the "Stage artefacts" step (lines 66-136):

• Replace all occurrences of ${{ inputs.bin-name }} with ${RESOLVED_BIN_NAME}
• This includes:
  • Directory creation: dist/${RESOLVED_BIN_NAME}_${os}_${arch}
  • Binary source path: target/${{ inputs.target }}/release/${RESOLVED_BIN_NAME}
  • Man page search: find ... -path "*/out/${RESOLVED_BIN_NAME}.1"
  • Install commands for both binary and man page

5. Add Validation for Multiple Binaries

File: file:.github/actions/rust-build-release/src/resolve_bin_name.py

Implement detection logic:

• Parse the manifest's [[bin]] array
• Count entries with explicit name fields
• If count > 1 and no --bin-name override provided:
  • Extract all binary names
  • Format error message listing all found binaries
  • Exit with error code 1 and GitHub Actions error annotation
• Example error: ::error::Multiple binary targets found: ['bin1', 'bin2', 'bin3']. Specify the bin-name input to select one.

6. Update Action Documentation

File: file:.github/actions/rust-build-release/README.md

Update the inputs table (lines 28-33):

• Change bin-name default from rust-toy-app to (auto-detected)
• Update description: "Binary name produced by the build. Auto-detected from Cargo.toml when omitted. Required when multiple binary targets exist."
• Add usage example showing auto-detection:

  # Auto-detect binary name (single binary project)
  - uses: ./.github/actions/rust-build-release
    with:
      target: x86_64-unknown-linux-gnu
      project-dir: my-project

• Add example for multiple binaries:

  # Explicit bin-name (multiple binary project)
  - uses: ./.github/actions/rust-build-release
    with:
      target: x86_64-unknown-linux-gnu
      project-dir: my-project
      bin-name: my-cli

7. Update Test Workflows

File: file:.github/workflows/rust-toy-app.yml

Remove the explicit bin-name: rust-toy-app parameter from the action call (line 60 would be removed) to validate auto-detection works for the test fixture.

8. Add Unit Tests

File: file:.github/actions/rust-build-release/tests/test_resolve_bin_name.py (new file)

Create comprehensive tests:

• Test auto-detection with single binary (using [[bin]] entry)
• Test auto-detection with package name fallback (no [[bin]] section)
• Test explicit --bin-name override
• Test error when multiple binaries exist without override
• Test error handling for missing manifest
• Test error handling for invalid TOML
• Use tmp_path fixtures to create test manifests
• Mock or import the script module for testing
• Follow patterns from file:tests/test_cargo_utils.py

9. Integration Testing

Verify the changes work end-to-end:

• The existing file:.github/workflows/rust-toy-app.yml workflow should pass without explicit bin-name
• Create a test case with multiple binaries to verify error handling
• Ensure the resolved binary name correctly propagates to artifact staging

Validation Checklist

sequenceDiagram
    participant Workflow
    participant Action
    participant ResolveScript
    participant CargoUtils
    participant Manifest as Cargo.toml
    
    Workflow->>Action: Call rust-build-release<br/>(no bin-name input)
    Action->>Action: Build release binary
    Action->>ResolveScript: resolve_bin_name.py<br/>--manifest-path Cargo.toml
    ResolveScript->>CargoUtils: read_manifest()
    CargoUtils->>Manifest: Parse TOML
    Manifest-->>CargoUtils: Parsed data
    CargoUtils-->>ResolveScript: manifest dict
    ResolveScript->>ResolveScript: Check [[bin]] count
    alt Single binary
        ResolveScript->>CargoUtils: get_bin_name()
        CargoUtils-->>ResolveScript: binary name
        ResolveScript-->>Action: Output: "my-binary"
        Action->>Action: Set RESOLVED_BIN_NAME=my-binary
        Action->>Action: Stage artefacts using<br/>RESOLVED_BIN_NAME
    else Multiple binaries
        ResolveScript-->>Action: Error: Multiple binaries found
        Action->>Workflow: Exit with error
    end

Loading

Import In IDE

🤖 Prompt for AI Agents

## Observations

The `rust-build-release` action currently defaults the `bin-name` input to `rust-toy-app`, a test fixture. This causes failures when workflows don't explicitly provide the binary name. The codebase already has `cargo_utils.py` with a `get_bin_name()` function that can extract binary names from `Cargo.toml` by checking `[[bin]]` entries or falling back to `[package].name`. The action's "Stage artefacts" step uses `bin-name` to locate the built binary and man page, but there's no validation for multiple binaries or auto-detection logic.

## Approach

The solution will modify the action to auto-detect the binary name from `Cargo.toml` when not explicitly provided. This involves: (1) removing the hardcoded default from `action.yml`, (2) creating a new Python script to resolve the binary name using existing `cargo_utils.py` functions, (3) adding validation to raise errors when multiple binaries exist without an explicit choice, and (4) updating the action workflow to call this script before the "Stage artefacts" step. This approach leverages existing utilities and maintains consistency with the repository's Python scripting patterns.

## Implementation Steps

### 1. Update Action Input Definition

**File:** `file:.github/actions/rust-build-release/action.yml`

- Remove the default value `rust-toy-app` from the `bin-name` input (line 18)
- Change `required: false` to keep it optional
- Update the description to clarify auto-detection behavior: "Name of the binary produced by the build. If not specified, will be auto-detected from Cargo.toml (requires exactly one binary target)"

### 2. Create Binary Name Resolution Script

**File:** `file:.github/actions/rust-build-release/src/resolve_bin_name.py` (new file)

Create a new Python script with PEP 723 metadata:
- Dependencies: `["plumbum", "syspath-hack>=0.4.0,<0.5.0", "typer"]`
- Import `cargo_utils` functions: `read_manifest`, `get_bin_name`
- Accept CLI arguments: `--manifest-path` (path to Cargo.toml), `--bin-name` (optional override)
- Logic flow:
  - If `--bin-name` is provided, validate it's non-empty and return it
  - Otherwise, read the manifest using `read_manifest()`
  - Check if `[[bin]]` array exists and has multiple entries
  - If multiple binaries exist, raise error: "Multiple binary targets found in Cargo.toml. Please specify bin-name input explicitly."
  - Otherwise, use `get_bin_name()` to extract the binary name
  - Print the resolved binary name to stdout for capture
- Use `typer` for CLI interface following the pattern in `file:.github/actions/rust-build-release/src/action_setup.py`
- Include proper error handling with GitHub Actions error annotations (`::error::`)

### 3. Add Binary Name Resolution Step to Action

**File:** `file:.github/actions/rust-build-release/action.yml`

Insert a new step after "Build release" (after line 65) and before "Stage artefacts":
- Name: "Resolve binary name"
- Condition: `if: contains(inputs.target, 'unknown-linux-') || contains(inputs.target, 'unknown-illumos')`
- Shell: bash
- Working directory: `${{ inputs.project-dir }}`
- Script logic:
  - Call `uv run --script "$GITHUB_ACTION_PATH/src/resolve_bin_name.py"` with `--manifest-path "${{ inputs.manifest-path }}"` and conditionally `--bin-name "${{ inputs.bin-name }}"` if provided
  - Capture output to `RESOLVED_BIN_NAME` environment variable
  - Export to `$GITHUB_ENV` for subsequent steps
  - Handle empty `inputs.bin-name` gracefully (only pass flag if non-empty)

### 4. Update Stage Artefacts Step

**File:** `file:.github/actions/rust-build-release/action.yml`

Modify the "Stage artefacts" step (lines 66-136):
- Replace all occurrences of `${{ inputs.bin-name }}` with `${RESOLVED_BIN_NAME}`
- This includes:
  - Directory creation: `dist/${RESOLVED_BIN_NAME}_${os}_${arch}`
  - Binary source path: `target/${{ inputs.target }}/release/${RESOLVED_BIN_NAME}`
  - Man page search: `find ... -path "*/out/${RESOLVED_BIN_NAME}.1"`
  - Install commands for both binary and man page

### 5. Add Validation for Multiple Binaries

**File:** `file:.github/actions/rust-build-release/src/resolve_bin_name.py`

Implement detection logic:
- Parse the manifest's `[[bin]]` array
- Count entries with explicit `name` fields
- If count > 1 and no `--bin-name` override provided:
  - Extract all binary names
  - Format error message listing all found binaries
  - Exit with error code 1 and GitHub Actions error annotation
- Example error: `::error::Multiple binary targets found: ['bin1', 'bin2', 'bin3']. Specify the bin-name input to select one.`

### 6. Update Action Documentation

**File:** `file:.github/actions/rust-build-release/README.md`

Update the inputs table (lines 28-33):
- Change `bin-name` default from `rust-toy-app` to `(auto-detected)`
- Update description: "Binary name produced by the build. Auto-detected from Cargo.toml when omitted. Required when multiple binary targets exist."
- Add usage example showing auto-detection:
  ```yaml
  # Auto-detect binary name (single binary project)
  - uses: ./.github/actions/rust-build-release
    with:
      target: x86_64-unknown-linux-gnu
      project-dir: my-project
  ```
- Add example for multiple binaries:
  ```yaml
  # Explicit bin-name (multiple binary project)
  - uses: ./.github/actions/rust-build-release
    with:
      target: x86_64-unknown-linux-gnu
      project-dir: my-project
      bin-name: my-cli
  ```

### 7. Update Test Workflows

**File:** `file:.github/workflows/rust-toy-app.yml`

Remove the explicit `bin-name: rust-toy-app` parameter from the action call (line 60 would be removed) to validate auto-detection works for the test fixture.

### 8. Add Unit Tests

**File:** `file:.github/actions/rust-build-release/tests/test_resolve_bin_name.py` (new file)

Create comprehensive tests:
- Test auto-detection with single binary (using `[[bin]]` entry)
- Test auto-detection with package name fallback (no `[[bin]]` section)
- Test explicit `--bin-name` override
- Test error when multiple binaries exist without override
- Test error handling for missing manifest
- Test error handling for invalid TOML
- Use `tmp_path` fixtures to create test manifests
- Mock or import the script module for testing
- Follow patterns from `file:tests/test_cargo_utils.py`

### 9. Integration Testing

Verify the changes work end-to-end:
- The existing `file:.github/workflows/rust-toy-app.yml` workflow should pass without explicit `bin-name`
- Create a test case with multiple binaries to verify error handling
- Ensure the resolved binary name correctly propagates to artifact staging

### Validation Checklist

```mermaid
sequenceDiagram
    participant Workflow
    participant Action
    participant ResolveScript
    participant CargoUtils
    participant Manifest as Cargo.toml
    
    Workflow->>Action: Call rust-build-release<br/>(no bin-name input)
    Action->>Action: Build release binary
    Action->>ResolveScript: resolve_bin_name.py<br/>--manifest-path Cargo.toml
    ResolveScript->>CargoUtils: read_manifest()
    CargoUtils->>Manifest: Parse TOML
    Manifest-->>CargoUtils: Parsed data
    CargoUtils-->>ResolveScript: manifest dict
    ResolveScript->>ResolveScript: Check [[bin]] count
    alt Single binary
        ResolveScript->>CargoUtils: get_bin_name()
        CargoUtils-->>ResolveScript: binary name
        ResolveScript-->>Action: Output: "my-binary"
        Action->>Action: Set RESOLVED_BIN_NAME=my-binary
        Action->>Action: Stage artefacts using<br/>RESOLVED_BIN_NAME
    else Multiple binaries
        ResolveScript-->>Action: Error: Multiple binaries found
        Action->>Workflow: Exit with error
    end
```

---

Execution Information

Branch: main
Commit: 9a4882b

---

💡 Tips

Supported Commands (Inside Comments)

• Use @traycerai generate to iterate on the previous version of the implementation plan.

Supported Commands (Inside Description)

• Add @traycerai ignore anywhere in the ticket description to prevent this ticket from being processed.
• Add @traycerai branch:<branch-name> anywhere in the ticket description to specify the target branch for the implementation plan.

Community

• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.