git-catcher 0.4.0

Smee.io-based GitHub push webhook auto-deploy CLI tool

Git Catcher

A Python CLI tool that receives GitHub push webhooks in real time via the Smee.io SSE proxy and automatically runs git pull and a custom deploy command for allowed branches.

Works behind firewalls/NAT, and supports automatic reconnection with exponential backoff on disconnection.

Installation

pip install -r git_catcher/requirements.txt

Dependencies

Package	Purpose
httpx	SSE stream HTTP client
rich	Colored console logging
python-dotenv	Load environment variables from .env
InquirerPy	Interactive CLI prompts (init command)
hypothesis	Property-based testing (dev)
pytest	Test framework (dev)

Quick Start

1. Interactive Setup (recommended)

python -m git_catcher.main init

Or using the shortcut:

python run.py init

Answer the interactive prompts to automatically generate a .env file and docker-compose.yml.

• Auto-generate Smee.io URL (opens browser)
• Randomly generate Webhook Secret
• Select repository path and allowed branches
• Configure Slack notifications

2. Manual Setup

Copy .env.example to create a .env file and fill in the values.

cp git_catcher/.env.example git_catcher/.env

Variable	Default	Description
SMEE_URL	https://smee.io/YOUR_CHANNEL_ID	Smee.io channel URL (create at smee.io/new)
WEBHOOK_SECRET	""	GitHub Webhook Secret (signature verification skipped if not set)
REPO_PATH	/path/to/your/repo	Local path to the target Git repository
ALLOWED_BRANCHES	main,master	Branches to deploy (comma-separated)
POST_PULL_COMMAND	""	Shell command to run after git pull
RECONNECT_DELAY	1	Initial reconnect wait time (seconds)
MAX_RECONNECT_DELAY	300	Maximum reconnect wait time (seconds)
ALLOWED_REPOS	""	Allowed repositories (owner/repo format, comma-separated). Auto-detected from REPO_PATH git remote origin if empty
SLACK_WEBHOOK_URL	""	Slack Incoming Webhook URL. Notifications skipped if empty
NOTIFY_ON_START	true	Send Slack notification on startup (true/false)
POLL_INTERVAL	0	Git status polling interval (seconds; 0 disables)
LOG_LEVEL	INFO	Log level (DEBUG, INFO, WARNING, ERROR)
LOG_FILE	""	Log file path (file logging disabled if empty)
SHOW_ALL_EVENTS	false	Log all push events (true/false)

2. Create a Smee.io Channel

1. Go to https://smee.io/new.
2. A unique channel URL is automatically generated (e.g. https://smee.io/AbCdEfGhIjKlMn).
3. Copy this URL. Use the same value for the GitHub Webhook Payload URL and SMEE_URL in your .env.

Note: The git-catcher init command automatically opens Smee.io in your browser.

3. Add a GitHub Repository Webhook

1. In your GitHub repository, go to Settings → Webhooks → Add webhook.
2. Configure as follows:

Field	Value
Payload URL	Smee.io channel URL (e.g. https://smee.io/AbCdEfGhIjKlMn)
Content type	application/json
Secret	Same value as WEBHOOK_SECRET in .env
Which events?	Select "Just the push event"
Active	Checked

3. Click Add webhook to save.

Note: Leaving the Secret blank also skips signature verification in Git Catcher. Setting a Secret is recommended for security.

3-1. Receive Webhooks for All Repositories via GitHub App (optional)

If you only need a single repository, use 3. Add a GitHub Repository Webhook above. To receive push webhooks from all repositories in your personal account (including future ones), create a GitHub App.

1) Create a GitHub App

Create an app at GitHub Settings → Developer settings → GitHub Apps → New GitHub App.

Field	Value	Notes
App name	Any name	e.g. my-git-catcher
Homepage URL	https://github.com/your-account	Required for app identification
Webhook URL	Smee.io channel URL	Destination to receive webhook data
Webhook Secret	Same value as WEBHOOK_SECRET in .env	Shared key to prevent payload tampering between server and GitHub

2) Permissions and Event Subscriptions

At the bottom of the creation form, configure:

• Repository Permissions → Contents: Set to Read-only or higher (required to detect code changes)
• Subscribe to events → Check Push (webhook fires only on code pushes)

3) Install the App on Your Account

This is the most important step. Creating the app alone is not enough — you must install it on your account.

1. On the created app page, click Install App.
2. Select your account and choose All repositories.
3. Click Install.

Selecting All repositories automatically applies the webhook to all existing repositories and any created in the future.

4) Security and Verification

Item	Description
Private Key (.pem)	Generate from the app settings page. Used for authentication when calling the GitHub API from your server
Recent Deliveries	View sent webhook payloads and test redelivery via Redeliver in the app settings → Advanced tab

4. .env Example

SMEE_URL must match the channel URL from Smee.io, and WEBHOOK_SECRET must match the Secret entered in GitHub Webhook settings.

SMEE_URL=https://smee.io/AbCdEfGhIjKlMn
WEBHOOK_SECRET=your-webhook-secret-here
REPO_PATH=/path/to/your/repo
ALLOWED_BRANCHES=main,master
POST_PULL_COMMAND=
ALLOWED_REPOS=
SLACK_WEBHOOK_URL=https://hooks.slack.com/services/T.../B.../xxx
NOTIFY_ON_START=true
POLL_INTERVAL=0
LOG_LEVEL=INFO
LOG_FILE=
SHOW_ALL_EVENTS=false

See the environment variables table for details on each variable.

Running

Basic Usage

# Option 1: run as module
python -m git_catcher.main

# Option 2: shortcut (recommended)
python run.py

On startup, git-catcher connects to the Smee.io SSE stream and waits for GitHub push events. When a push is detected on an allowed branch, it automatically runs git fetch → git checkout → git pull → post-pull command in sequence.

Startup Notification

When NOTIFY_ON_START=true, git-catcher sends a Slack notification on startup containing:

• Repository name
• Allowed branch list
• Hostname
• External IP address
• Start time (UTC)

CLI Commands

Command	Description
git-catcher init	Interactive setup (generates .env and docker-compose.yml)
git-catcher run	Run git-catcher (default behavior)

CLI Options (run command)

Option	Description
-v	DEBUG logging for git_catcher module only
-vv	DEBUG logging for all modules
-vvvv	Also print raw webhook payloads
--show-all-events	Log all push events (deployment filtering still applies)
--log-file PATH	Log file path (also writes DEBUG logs to file when set)
--log-level LEVEL	Log level (DEBUG, INFO, WARNING, ERROR)

# Basic run
python run.py

# git_catcher module DEBUG + write to log file
python run.py -v --log-file deploy.log

# Show all push events + full DEBUG
python run.py -vv --show-all-events

# Interactive setup
python run.py init

Key Features

• Interactive setup: Answer prompts with git-catcher init to auto-generate .env and docker-compose.yml
• Quick start: Run with python run.py
• Startup notification: Sends a Slack notification on start when NOTIFY_ON_START=true (includes repo, branches, host, IP)
• Auto repo detection: Extracts owner/repo from REPO_PATH git remote origin URL when ALLOWED_REPOS is not set
• Slack deploy notifications: Notifies a Slack channel on deploy success/failure when SLACK_WEBHOOK_URL is set
• SSE reconnect recovery: Resumes from the last received event using Last-Event-ID on disconnection
• Rich console logging: Readable colored output with timestamp (HH:MM:SS.ms) format

Verifying It Works

1. Run Git Catcher:

   python run.py
   

2. When you see the SSE stream connected log, the connection is established.

3. If NOTIFY_ON_START=true, a startup notification is sent to Slack.

4. Push a commit to an allowed branch:

   git add .
   git commit -m "test webhook"
   git push origin main
   

5. Verify the following logs appear in order in the Git Catcher terminal:

   • Push detected: [main] test webhook
   • git fetch → git checkout → git pull complete
   • POST_PULL_COMMAND executed (if configured)
   • Slack notification sent (if configured)

If something is wrong, check the Recent Deliveries tab on the GitHub Webhook page to inspect delivery status.

Tests

pytest tests/ -v