smyklot

README

Smyklot

GitHub App for automated PR approvals and merges based on CODEOWNERS

Overview

Smyklot is a GitHub App that automates pull request approvals and merges by validating permissions against your repository's CODEOWNERS file. Simply comment on a PR with commands or add emoji reactions, and Smyklot handles the rest.

Features

• CODEOWNERS-based permissions - Only repository owners defined in .github/CODEOWNERS can approve/merge
• Multiple command formats - Supports slash commands (/approve), mentions (@smyklot approve), and bare commands (lgtm, merge)
• Merge method control - Explicit squash and rebase commands with intelligent fallback for merge
• Reaction-based commands - Use 👍 to approve, 🚀 to merge, or ❤️ to cleanup
• Cleanup command - Remove all bot reactions, approvals, and comments with a single command
• Approval deduplication - Prevents duplicate approvals with smart reaction handling
• Flexible configuration - Configure via SMYKLOT_CONFIG JSON, individual variables, or environment variables
• Emoji feedback - Get instant visual confirmation with ✅ (success), ❌ (error), or ⚠️ (warning)
• Comment edit/delete handling - Reacts to command edits and removes reactions when commands are deleted
• Reaction removal tracking - Automatically removes approvals/merges when reactions are removed
• Multi-command support - Execute multiple commands in a single comment
• Security-first design - Follows GitHub Actions best practices with minimal permissions
• Zero external dependencies - Runs entirely on GitHub Actions
• TDD implementation - 130+ passing tests

Quick Start

Prerequisites

• GitHub repository with Actions enabled
• .github/CODEOWNERS file in your repository

Installation

Option 1: GitHub App (Recommended)

1. Install the Smyklot GitHub App on your repository

2. Create .github/CODEOWNERS:

   * @username
   

3. Comment on PRs with commands or add reactions

Option 2: Manual Workflow

Copy the workflow file to your repository:

cp .github/workflows/pr-commands.yaml your-repo/.github/workflows/

Usage

Comment Commands

Smyklot responds to these commands in PR comments:

Command	Aliases	Format	Description
approve	lgtm, accept	/approve, @smyklot approve, approve	Approve the pull request
merge	-	/merge, @smyklot merge, merge	Merge the pull request (with fallback)
squash	-	/squash, @smyklot squash, squash	Squash merge the pull request
rebase	-	/rebase, @smyklot rebase, rebase	Rebase merge the pull request
unapprove	-	/unapprove, @smyklot unapprove	Remove approval
cleanup	-	/cleanup, @smyklot cleanup, cleanup	Remove all bot reactions, approvals, and comments
help	-	/help, @smyklot help	Show help information

Command Formats:

• Slash commands: /approve, /merge, /squash, /rebase, /unapprove, /cleanup, /help
• Mention commands: @smyklot approve, @smyklot merge, @smyklot squash, @smyklot rebase, @smyklot unapprove, @smyklot cleanup
• Bare commands: approve, accept, lgtm, merge, squash, rebase, cleanup (exact match only)

All commands are case-insensitive.

Reaction Commands

Reaction	Action
👍	Approve the pull request
🚀	Merge the pull request
❤️	Cleanup (remove all bot reactions, approvals, and comments)

Note: Reactions must be added to the PR description, not to comments. Removing a reaction will automatically undo the corresponding action (remove approval/merge labels).

Multiple Commands

You can use multiple non-contradicting commands in a single comment:

/approve
/merge

or

lgtm merge

Commands will be executed in order: approve first, then merge.

Examples

Approving a PR

Any of these will approve the PR:

/approve

@smyklot approve

lgtm

Or add a 👍 reaction to the PR description.

Merging a PR

Merge with default method (with fallback to squash/rebase if merge commits disallowed):

/merge

Or add a 🚀 reaction to the PR description.

Squash Merging

/squash

Rebase Merging

/rebase

Removing Approval

/unapprove

Or remove your 👍 reaction from the PR description.

Cleanup

Remove all bot reactions, approvals, and comments:

/cleanup

Or add a ❤️ reaction to the PR description.

Note: Cleanup cannot be combined with other commands.

Configuration

CODEOWNERS Setup

Create .github/CODEOWNERS in your repository:

# Global owners can approve/merge any PR
* @username1 @username2

Currently only global owners (* pattern) are supported. Path-specific owners will be added in Phase 2.

Bot Configuration

Smyklot can be configured via repository variables (Settings → Secrets and variables → Actions → Variables).

Configuration Precedence: CLI flags > Environment variables > Repository variables > Defaults

Option 1: Full JSON Configuration (Recommended)

Set a SMYKLOT_CONFIG repository variable with your complete configuration:

{
  "quiet_success": false,
  "quiet_reactions": false,
  "quiet_pending": false,
  "allowed_commands": ["approve", "merge"],
  "command_aliases": {
    "ok": "approve",
    "ship": "merge"
  },
  "command_prefix": "/",
  "disable_mentions": false,
  "disable_bare_commands": false,
  "disable_unapprove": false,
  "disable_reactions": false,
  "disable_deleted_comments": false,
  "allow_self_approval": false
}

Option 2: Individual Variables

Configure individual settings via repository variables or environment variables with SMYKLOT_ prefix:

Variable	Type	Default	Description
SMYKLOT_QUIET_SUCCESS	boolean	false	Disable success feedback comments
SMYKLOT_QUIET_REACTIONS	boolean	false	Disable reaction-based approval/merge comments
SMYKLOT_QUIET_PENDING	boolean	false	Disable pending CI comments (reactions only for "merge after CI")
SMYKLOT_ALLOWED_COMMANDS	list	all	Limit which commands are allowed
SMYKLOT_COMMAND_ALIASES	map	default	Define custom command aliases
SMYKLOT_COMMAND_PREFIX	string	/	Custom command prefix
SMYKLOT_DISABLE_MENTIONS	boolean	false	Disable mention commands
SMYKLOT_DISABLE_BARE_COMMANDS	boolean	false	Disable bare commands
SMYKLOT_DISABLE_UNAPPROVE	boolean	false	Disable unapprove command
SMYKLOT_DISABLE_REACTIONS	boolean	false	Disable reaction-based approvals/merges
SMYKLOT_DISABLE_DELETED_COMMENTS	boolean	false	Disable handling of deleted comments
SMYKLOT_ALLOW_SELF_APPROVAL	boolean	false	Allow PR authors to approve their own PRs
SMYKLOT_BOT_USERNAME	string	smyklot[bot]	Bot username for cleanup operations (GitHub App format: {app-slug}[bot])

Configuration Examples

Example 1: Quiet Mode

Only show emoji reactions, no success comments:

# In workflow or as repository variable
env:
  SMYKLOT_QUIET_SUCCESS: "true"

Result: User sees only ✅ reaction, no "PR Approved" comment.

Example 2: Custom Prefix

Use ! instead of / for commands:

env:
  SMYKLOT_COMMAND_PREFIX: "!"

Users can now use !approve and !merge.

Example 3: Command Aliases

Create shortcuts for commands:

env:
  SMYKLOT_COMMAND_ALIASES: '{"app":"approve","a":"approve","m":"merge"}'

Users can use /app, /a, or /m as shortcuts.

Example 4: Reactions Only

Disable comment-based commands, only allow reactions:

{
  "disable_mentions": true,
  "disable_bare_commands": true,
  "command_prefix": "disabled"
}

Only 👍 and 🚀 reactions will work.

Example 5: Disable Reaction Tracking

Don't remove approvals/merges when reactions are removed:

env:
  SMYKLOT_DISABLE_DELETED_COMMENTS: "true"

Example 6: Allow Self-Approval

⚠️ Not recommended for production - Allow PR authors to approve their own PRs:

env:
  SMYKLOT_ALLOW_SELF_APPROVAL: "true"

or via JSON:

{
  "allow_self_approval": true
}

Security Note: By default, Smyklot prevents self-approval to enforce separation of duties. Only enable this in development/testing environments.

Architecture

How It Works

1. User comments a command or adds a reaction on a PR
2. GitHub triggers issue_comment webhook
3. pr-commands.yaml workflow starts
4. Smyklot:
   • Parses the command (supports slash, mention, and bare formats)
   • Or processes reactions (👍 for approve, 🚀 for merge, ❤️ for cleanup)
   • Validates command combinations (cleanup cannot be combined with others)
   • Checks for duplicate approvals (prevents re-approving for both commands and reactions)
   • Fetches .github/CODEOWNERS via GitHub API
   • Checks user permissions
   • Calls GitHub API to approve/merge/cleanup
   • For merge: tries specified method or falls back (merge → squash → rebase)
   • Posts reactions and feedback
5. On comment edit/delete or reaction removal, updates accordingly

Permission System

Phase 1 (Current):

• Only global owners (* @username) are supported
• Global owners can approve/merge any PR
• Reaction-based approvals/merges with tracking
• Self-approval prevention (configurable, disabled by default)
• Fail-closed CODEOWNERS parsing (returns error if file is corrupted)

Phase 2 (Planned):

• Path-specific ownership patterns
• Scoped permissions based on changed files
• Team support (@org/team-name)
• Required approvals count

Security

Smyklot implements defense-in-depth security practices:

Input Validation:

• Comment body length validation (max 10KB) - prevents DoS attacks
• Repository owner/name format validation - prevents path traversal
• All inputs passed via environment variables (no shell interpolation)

API Security:

• Parameterized GraphQL queries - prevents injection attacks
• HTTP client timeout (30s) - prevents hung requests
• Exponential backoff retry logic - handles rate limiting gracefully
• Connection pooling - optimizes resource usage

Access Control:

• CODEOWNERS-based authorization with fail-closed parsing
• Self-approval prevention (configurable, disabled by default)
• Minimal workflow permissions (contents: read, pull-requests: write)
• Token-based authentication via GitHub App

Data Protection:

• Sensitive data sanitization in logs (tokens, keys, secrets redacted)
• Maximum CODEOWNERS file size (1MB) - prevents memory exhaustion
• No repository checkout required (CODEOWNERS fetched via API)

Supply Chain Security:

• Actions pinned by commit digest
• Go dependencies verified (go mod verify)
• Docker images use minimal base (FROM scratch)

Development

Requirements

• Go 1.25+
• mise for tool management
• Task for task automation

Setup

# Clone repository
git clone https://github.com/smykla-labs/smyklot.git
cd smyklot

# Install tools
mise install

# Download dependencies
go mod download

# Run tests
task test

Project Structure

smyklot/
├── cmd/
│   └── github-action/       # GitHub Actions entrypoint
├── pkg/
│   ├── commands/            # Command parser (slash, mention, bare)
│   ├── config/              # Configuration management (Viper)
│   ├── feedback/            # User feedback system (reactions, comments)
│   ├── github/              # GitHub API client
│   └── permissions/         # CODEOWNERS parser & permission checker
├── .github/workflows/       # GitHub Actions workflows
├── .goreleaser.yml          # GoReleaser config for releases
├── .mise.toml               # Tool versions
├── Dockerfile               # Docker image for GitHub Actions
├── Taskfile.yaml            # Task automation
└── go.mod                   # Go module definition

Available Tasks

task             # Show available tasks
task test        # Run all tests with coverage
task test:unit   # Run unit tests only
task lint        # Run all linters
task build       # Build binaries
task clean       # Clean build artifacts

Testing

All tests use Ginkgo/Gomega BDD framework:

# Run all tests
task test

# Run specific package
ginkgo -r pkg/commands/

# Watch mode for TDD
ginkgo watch -r

Current test coverage: 130+ tests passing

• 52+ command parser tests
• 12 CODEOWNERS parser tests
• 30 permission checker tests
• 30 feedback system tests
• 18+ GitHub client tests

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feat/amazing-feature)
3. Write tests first (TDD)
4. Implement the feature
5. Ensure all checks pass: task lint && task test
6. Commit with conventional commits (feat:, fix:, docs:, etc.)
7. Push to your fork
8. Open a pull request

Roadmap

Phase 1: GitHub Actions Bot ✅

• Command parser (slash, mention, bare)
• Multi-command support
• Merge method commands (merge, squash, rebase)
• Merge method fallback (merge → squash → rebase)
• Cleanup command (remove all bot reactions, approvals, comments)
• Approval deduplication (prevent duplicate approvals)
• Reaction-based approvals/merges/cleanup (👍, 🚀, ❤️)
• Reaction removal tracking
• Comment edit/delete handling
• CODEOWNERS parser (global owners)
• Permission checker
• GitHub API client
• Feedback system (emoji + comments)
• Configuration system (Viper)
• GitHub Actions workflows
• Docker-based GitHub Action
• Documentation

Phase 2: Enhanced Permissions (Planned)

• Path-specific ownership patterns
• Scoped approval requirements based on changed files
• Team support in CODEOWNERS (@org/team-name)
• Self-approval prevention (configurable)
• Required approvals count

Phase 3: Kubernetes Deployment (Future)

Prerequisites (Security Hardening):

• GraphQL injection prevention
• HTTP client timeout and connection pooling
• Rate limiting and retry logic
• Input validation
• Fail-closed CODEOWNERS parsing

Remaining Work:

• Refactor global mutable state to request-scoped parameters
• Add context.Context propagation throughout
• Implement HTTP webhook server
• Add concurrency tests with -race flag
• Implement comprehensive audit logging
• Kubernetes deployment (Helm chart)
• Prometheus metrics
• Migration strategy

Estimated Effort: 18-30 days

Phase 4: Discord Integration (Future)

• Discord bot
• Unified command system
• Cross-platform notifications
• Status synchronization

License

MIT License - see LICENSE for details

Acknowledgments

Built with:

• Ginkgo - BDD testing framework
• Gomega - Matcher library
• Viper - Configuration management
• Cobra - CLI framework
• mise - Tool version manager
• Task - Task runner
• GoReleaser - Release automation

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Made with ❤️ by @bartsmykla