tunnel

GitLab Tunnel

A gRPC-based reverse tunnel implementation, mostly intended for the GitLab Agent for Kubernetes project.

Overview

This project provides a gRPC-based reverse tunnel system that allows clients to establish secure connections back to GitLab instances (KAS).

• Routing from server to proper client
• Bidirectional streaming communication

Architecture

The system consists of two main components:

• Tunnel Server (tunserver/): Handles incoming client connections and routes requests to appropriate gateways (the server with the open connection to the client).
• Tunnel Client (tunclient/): Manages connections from agents to the tunnel server

Development

Prerequisites

• Go (see version in go.mod
• buf for Protocol Buffer management
• golangci-lint for linting

Or use mise to automatically install the correct versions:

mise install

Testing

# Run all tests
make test

Code Generation

The project uses Protocol Buffers and generated mocks:

# Generate protos code and mocks
make generate

# Generate only protos
make protos

# Generate only mocks
make mocks

Linting and Formatting

# Run linters
make lint

# Format code and fix linting issues
make fmt

License

MIT License - see LICENSE for details.