Slack MCP Client in Go

This project provides a Slack bot client that serves as a bridge between Slack and Model Context Protocol (MCP) servers. By leveraging Slack as the user interface, it allows LLM models to interact with multiple MCP servers using standardized MCP tools.

Overview

This project implements a Slack bot client that acts as a bridge between Slack and Model Context Protocol (MCP) servers. It uses Slack as a user interface while enabling LLM models to communicate with various MCP servers through standardized MCP tools.

Important distinction: This client is not designed to interact with the Slack API directly as its primary purpose. However, it can achieve Slack API functionality by connecting to a dedicated Slack MCP server (such as modelcontextprotocol/servers/slack) alongside other MCP servers.

How It Works

flowchart LR
    User([User]) --> SlackBot
    
    subgraph SlackBotService[Slack Bot Service]
        SlackBot[Slack Bot] <--> MCPClient[MCP Client]
    end
    

    
    MCPClient <--> MCPServer1[MCP Server 1]
    MCPClient <--> MCPServer2[MCP Server 2]
    MCPClient <--> MCPServer3[MCP Server 3]
    
    MCPServer1 <--> Tools1[(Tools)]
    MCPServer2 <--> Tools2[(Tools)]
    MCPServer3 <--> Tools3[(Tools)]
    
    style SlackBotService fill:#F8F9F9,stroke:#333,stroke-width:2px
    style SlackBot fill:#F4D03F,stroke:#333,stroke-width:2px
    style MCPClient fill:#2ECC71,stroke:#333,stroke-width:2px
    style MCPServer1 fill:#E74C3C,stroke:#333,stroke-width:2px
    style MCPServer2 fill:#E74C3C,stroke:#333,stroke-width:2px
    style MCPServer3 fill:#E74C3C,stroke:#333,stroke-width:2px
    style Tools1 fill:#9B59B6,stroke:#333,stroke-width:2px
    style Tools2 fill:#9B59B6,stroke:#333,stroke-width:2px
    style Tools3 fill:#9B59B6,stroke:#333,stroke-width:2px

User interacts only with Slack, sending messages through the Slack interface
Slack Bot Service is a single process that includes:
- The Slack Bot component that handles Slack messages
- The MCP Client component that communicates with MCP servers
The MCP Client forwards requests to the appropriate MCP Server(s)
MCP Servers execute their respective tools and return results

Features

✅ Multi-Mode MCP Client:
- Server-Sent Events (SSE) for real-time communication
- HTTP transport for JSON-RPC
- stdio for local development and testing
✅ Slack Integration:
- Uses Socket Mode for secure, firewall-friendly communication
- Works with both channels and direct messages
- Rich message formatting with Markdown and Block Kit
- Automatic conversion of quoted strings to code blocks for better readability
ED48
✅ Multi-Provider LLM Support:
- OpenAI (GPT-4, GPT-4o, etc.)
- Anthropic (Claude 3.5 Sonnet, etc.)
- Ollama (Local LLMs like Llama, Mistral, etc.)
- Factory pattern for easy provider switching
- LangChain gateway for unified API
✅ Custom Prompt Engineering:
- System Prompts - Define custom AI assistant behavior and personality
✅ RAG (Retrieval-Augmented Generation):
- LangChain Go Compatible - Drop-in replacement for standard vector stores
- Document Processing - PDF ingestion with intelligent chunking
- CLI Tools - Command-line utilities for document management
- Extensible Design - Easy to add SQLite, Redis, or vector embeddings
✅ Tool Registration: Dynamically register and call MCP tools
✅ Configuration Management:
- JSON-based MCP server configuration
- Environment variable support
- Multiple transport modes (HTTP/SSE, stdio)
✅ Production Ready:
- Docker container support
- Kubernetes Helm charts
- Comprehensive logging and error handling
- 88%+ test coverage

Installation

From Binary Release

Download the latest binary from the GitHub releases page or install using Go:

# Install latest version using Go
go install github.com/tuannvm/slack-mcp-client@latest

# Or build from source
git clone https://github.com/tuannvm/slack-mcp-client.git
cd slack-mcp-client
make build
# Binary will be in ./bin/slack-mcp-client

Running Locally with Binary

After installing the binary, you can run it locally with the following steps:

Set up environment variables:

# Using environment variables directly
export SLACK_BOT_TOKEN="xoxb-your-bot-token"
export SLACK_APP_TOKEN="xapp-your-app-token"
export OPENAI_API_KEY="sk-your-openai-key"
export OPENAI_MODEL="gpt-4o"
export LOG_LEVEL="info"

# Or create a .env file and source it
cat > .env << EOL
SLACK_BOT_TOKEN="xoxb-your-bot-token"
SLACK_APP_TOKEN="xapp-your-app-token"
OPENAI_API_KEY="sk-your-openai-key"
OPENAI_MODEL="gpt-4o"
LOG_LEVEL="info"
EOL

source .env

Create an MCP servers configuration file:

# Create mcp-servers.json in the current directory
cat > mcp-servers.json << EOL
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "$HOME"],
      "env": {}
    }
  }
}
EOL

Run the application:

# Run with default settings (looks for mcp-servers.json in current directory)
slack-mcp-client

# Or specify a custom config file location
slack-mcp-client --config /path/to/mcp-servers.json

# Enable debug mode
slack-mcp-client --debug

# Specify OpenAI model
slack-mcp-client --openai-model gpt-4o-mini

The application will connect to Slack and start listening for messages. You can check the logs for any errors or connection issues.

RAG Setup and Usage

The client includes an improved RAG (Retrieval-Augmented Generation) system that's compatible with LangChain Go and provides professional-grade performance:

Quick Start with RAG

Enable RAG in your configuration:

{
  "llm_provider": "openai",
  "llm_providers": {
    "openai": {
      "type": "openai", 
      "model": "gpt-4o",
      "rag_config": {
        "enabled": true,
        "provider": "json",
        "database_path": "./knowledge.json",
        "chunk_size": 1000,
        "chunk_overlap": 200,
        "max_results": 10
      }
    }
  }
}

Ingest documents using CLI:

# Ingest PDF files from a directory
slack-mcp-client --rag-ingest ./company-docs --rag-db ./knowledge.json

# Test search functionality
slack-mcp-client --rag-search "vacation policy" --rag-db ./knowledge.json

# Get database statistics
slack-mcp-client --rag-stats --rag-db ./knowledge.json

Use in Slack:

Once configured, the LLM can automatically search your knowledge base:

User: "What's our vacation policy?"

AI: "Let me search our knowledge base for vacation policy information..." (Automatically searches RAG database)

AI: "Based on our company policy documents, you get 15 days of vacation..."

RAG Features

🎯 Smart Search: Advanced relevance scoring with word frequency, filename boosting, and phrase matching
🔗 LangChain Compatible: Drop-in replacement for standard vector stores
📈 Extensible: Easy to add vector embeddings and other backends

Custom Prompts and Assistants

The client supports advanced prompt engineering capabilities for creating specialized AI assistants:

System Prompts

Create custom AI personalities and behaviors:

# Create a custom system prompt file
cat > sales-assistant.txt << EOL
You are SalesGPT, a helpful sales assistant specializing in B2B software sales.

Your expertise includes:
- Lead qualification and discovery
- Solution positioning and value propositions  
- Objection handling and negotiation
- CRM best practices and sales processes

Always:
- Ask qualifying questions to understand prospect needs
- Provide specific, actionable sales advice
- Reference industry best practices
- Maintain a professional yet friendly tone

When discussing pricing, always emphasize value over cost.
EOL

# Use the custom prompt
slack-mcp-client --system-prompt ./sales-assistant.txt

Configuration-Based Prompts

Define prompts in your configuration:

{
  "llm_provider": "openai",
  "llm_providers": {
    "openai": {
      "type": "openai",
      "model": "gpt-4o",
      "system_prompt": "You are a helpful DevOps assistant specializing in Kubernetes and cloud infrastructure.",
      "conversation_starters": [
        "Help me debug a Kubernetes pod issue",
        "Explain best practices for CI/CD pipelines", 
        "Review my Dockerfile for optimization"
      ]
    }
  }
}

Assistant Roles

Create specialized assistants for different use cases:

DevOps Assistant: Kubernetes, Docker, CI/CD expertise
Sales Assistant: Lead qualification, objection handling
HR Assistant: Policy questions, onboarding guidance
Support Assistant: Customer issue resolution
Code Review Assistant: Security, performance, best practices

Kubernetes Deployment with Helm

For deploying to Kubernetes, a Helm chart is available in the helm-chart directory. This chart provides a flexible way to deploy the slack-mcp-client with proper configuration and secret management.

Installing from GitHub Container Registry

The Helm chart is also available directly from GitHub Container Registry, allowing for easier installation without needing to clone the repository:

# Add the OCI repository to Helm (only needed once)
helm registry login ghcr.io -u USERNAME -p GITHUB_TOKEN

# Pull the Helm chart
helm pull oci://ghcr.io/tuannvm/charts/slack-mcp-client --version 0.1.0

# Or install directly
helm install my-slack-bot oci://ghcr.io/tuannvm/charts/slack-mcp-client --version 0.1.0 -f values.yaml

You can check available versions by visiting the GitHub Container Registry in your browser.

Prerequisites

Kubernetes 1.16+
Helm 3.0+
Slack Bot and App tokens

Basic Installation

# Create a values file with your configuration
cat > values.yaml << EOL
secret:
  create: true

env:
  SLACK_BOT_TOKEN: "xoxb-your-bot-token"
  SLACK_APP_TOKEN: "xapp-your-app-token"
  OPENAI_API_KEY: "sk-your-openai-key"
  OPENAI_MODEL: "gpt-4o"
  LOG_LEVEL: "info"

# Optional: Configure MCP servers
configMap:
  create: true
EOL

# Install the chart
helm install my-slack-bot ./helm-chart/slack-mcp-client -f values.yaml

Configuration Options

The Helm chart supports various configuration options including:

Setting resource limits and requests
Configuring MCP servers via ConfigMap
Managing sensitive data via Kubernetes secrets
Customizing deployment parameters

For more details, see the Helm chart README.

Using the Docker Image from GHCR

The Helm chart uses the Docker image from GitHub Container Registry (GHCR) by default. You can specify a particular version or use the latest tag:

# In your values.yaml
image:
  repository: ghcr.io/tuannvm/slack-mcp-client
  tag: "latest"  # Or use a specific version like "1.0.0"
  pullPolicy: IfNotPresent

To manually pull the image:

# Pull the latest image
docker pull ghcr.io/tuannvm/slack-mcp-client:latest

# Or pull a specific version
docker pull ghcr.io/tuannvm/slack-mcp-client:1.0.0

If you're using private images, you can configure image pull secrets in your values:

imagePullSecrets:
  - name: my-ghcr-secret

Docker Compose for Local Testing

For local testing and development, you can use Docker Compose to easily run the slack-mcp-client along with additional MCP servers.

Setup

Create a .env file with your credentials:

# Create .env file from example
cp .env.example .env
# Edit the file with your credentials
nano .env

Create a mcp-servers.json file (or use the example):

# Create mcp-servers.json from example
cp mcp-servers.json.example mcp-servers.json
# Edit if needed
nano mcp-servers.json

Start the services:

# Start services in detached mode
docker-compose up -d

# View logs
docker-compose logs -f

# Stop services
docker-compose down

Docker Compose Configuration

The included docker-compose.yml provides:

Environment variables loaded from .env file
Volume mounting for MCP server configuration
Examples of connecting to additional MCP servers (commented out)

version: '3.8'

services:
  slack-mcp-client:
    image: ghcr.io/tuannvm/slack-mcp-client:latest
    container_name: slack-mcp-client
    environment:
      - SLACK_BOT_TOKEN=${SLACK_BOT_TOKEN}
      - SLACK_APP_TOKEN=${SLACK_APP_TOKEN}
      - OPENAI_API_KEY=${OPENAI_API_KEY}
      - OPENAI_MODEL=${OPENAI_MODEL:-gpt-4o}
    volumes:
      - ./mcp-servers.json:/app/mcp-servers.json:ro

You can easily extend this setup to include additional MCP servers in the same network.

Slack App Setup

Create a new Slack app at https://api.slack.com/apps
Enable Socket Mode and generate an app-level token
Add the following Bot Token Scopes:
- app_mentions:read
- chat:write
- im:history
- im:read
- im:write
- users:read
- users.profile:read
Enable Event Subscriptions and subscribe to:
- app_mention
- message.im
Install the app to your workspace

For detailed instructions on Slack app configuration, token setup, required permissions, and troubleshooting common issues, see the Slack Configuration Guide.

LLM Integration

The client supports multiple LLM providers through a flexible integration system:

LangChain Gateway

The LangChain gateway enables seamless integration with various LLM providers:

OpenAI: Native support for GPT models (default)
Ollama: Local LLM support for models like Llama, Mistral, etc.
Extensible: Can be extended to support other LangChain-compatible providers

LLM-MCP Bridge

The custom LLM-MCP bridge layer enables any LLM to use MCP tools without requiring native function-calling capabilities:

Universal Compatibility: Works with any LLM, including those without function-calling
Pattern Recognition: Detects when a user prompt or LLM response should trigger a tool call
Natural Language Support: Understands both structured JSON tool calls and natural language requests

Configuration

LLM providers can be configured via environment variables or command-line flags:

# Set OpenAI as the provider (default)
export LLM_PROVIDER="openai"
export OPENAI_MODEL="gpt-4o"

# Use Anthropic
export LLM_PROVIDER="anthropic"
export ANTHROPIC_API_KEY="your-anthropic-api-key"
export ANTHROPIC_MODEL="claude-3-5-sonnet-20241022"

# Or use Ollama
export LLM_PROVIDER="ollama"
export LANGCHAIN_OLLAMA_URL="http://localhost:11434"
export LANGCHAIN_OLLAMA_MODEL="llama3"

Switching Between Providers

You can easily switch between providers by changing the LLM_PROVIDER environment variable:

# Use OpenAI
export LLM_PROVIDER=openai

# Use Anthropic
export LLM_PROVIDER=anthropic

# Use Ollama (local)
export LLM_PROVIDER=ollama

Configuration

The client uses two main configuration approaches:

Environment Variables

Configure LLM providers and Slack integration using environment variables:

Variable	Description	Default
SLACK_BOT_TOKEN	Bot token for Slack API	(required)
SLACK_APP_TOKEN	App-level token for Socket Mode	(required)
OPENAI_API_KEY	API key for OpenAI authentication	(required)
OPENAI_MODEL	OpenAI model to use	gpt-4o
ANTHROPIC_API_KEY	API key for Anthropic authentication	(required for Anthropic)
ANTHROPIC_MODEL	Anthropic model to use	claude-3-5-sonnet-20241022
LOG_LEVEL	Logging level (debug, info, warn, error)	info
LLM_PROVIDER	LLM provider to use (openai, anthropic, ollama)	openai
LANGCHAIN_OLLAMA_URL	URL for Ollama when using LangChain	http://localhost:11434
LANGCHAIN_OLLAMA_MODEL	Model name for Ollama when using LangChain	llama3

MCP Server Configuration

MCP servers are configured via a JSON configuration file (default: mcp-servers.json):

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/directory"],
      "env": {}
    },
    "github": {
      "command": "github-mcp-server",
      "args": ["stdio"],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "your-token"
      }
    },
    "web-api": {
      "mode": "http",
      "url": "http://localhost:8080/mcp",
      "initialize_timeout_seconds": 30
    }
  }
}

For detailed configuration options, see the Implementation Notes.

Slack-Formatted Output

The client includes a comprehensive Slack-formatted output system that enhances message display in Slack:

Automatic Format Detection: Automatically detects message type (plain text, markdown, JSON Block Kit, structured data) and applies appropriate formatting
Markdown Formatting: Supports Slack's mrkdwn syntax with automatic conversion from standard Markdown
- Converts **bold** to *bold* for proper Slack bold formatting
- Preserves inline code, block quotes, lists, and other formatting elements
Quoted String Enhancement: Automatically converts double-quoted strings to inline code blocks for better visualization
- Example: "namespace-name" becomes `namespace-name` in Slack
- Improves readability of IDs, timestamps, and other quoted values
Block Kit Integration: Converts structured data to Block Kit layouts for better visual presentation
- Automatically validates against Slack API limits
- Falls back to plain text if Block Kit validation fails

For more details, see the Slack Formatting Guide.

Transport Modes

The client supports three transport modes:

SSE (default): Uses Server-Sent Events for real-time communication with the MCP server
HTTP: Uses HTTP POST requests with JSON-RPC for communication
stdio: Uses standard input/output for local development and testing

Documentation

Comprehensive documentation is available in the docs/ directory:

Configuration & Setup

Slack Configuration Guide - Complete guide for setting up your Slack app, including required permissions, tokens, and troubleshooting common issues

Development & Implementation

Implementation Notes - Detailed technical documentation covering the current architecture, core components, and implementation details
Requirements Specification - Comprehensive requirements documentation including implemented features, quality requirements, and future enhancements

User Guides

Slack Formatting Guide - Complete guide to message formatting including Markdown-to-Slack conversion, Bl 85F7 ock Kit layouts, and automatic format detection
RAG Implementation Guide - Detailed guide for the improved RAG system with LangChain Go compatibility and performance optimizations
RAG SQLite Implementation - Implementation plan for native Go SQLite integration with ChatGPT-like upload experience
Testing Guide - Comprehensive testing documentation covering unit tests, integration tests, manual testing procedures, and debugging

Quick Links

Setup: Start with the Slack Configuration Guide for initial setup
RAG: Check the RAG Implementation Guide for document knowledge base integration
Formatting: See the Slack Formatting Guide for message formatting capabilities
RAG SQLite: See the RAG SQLite Implementation for native Go implementation with modern upload UX
Development: Check the Implementation Notes for technical details
Testing: Use the Testing Guide for testing procedures and debugging

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

CI/CD and Releases

This project uses GitHub Actions for continuous integration and GoReleaser for automated releases.

Continuous Integration Checks

Our CI pipeline performs the following checks on all PRs and commits to the main branch:

Code Quality

Linting: Using golangci-lint to check for common code issues and style violations
Go Module Verification: Ensuring go.mod and go.sum are properly maintained
Formatting: Verifying code is properly formatted with gofmt

Security

Vulnerability Scanning: Using govulncheck to check for known vulnerabilities in dependencies
Dependency Scanning: Using Trivy to scan for vulnerabilities in dependencies
SBOM Generation: Creating a Software Bill of Materials for dependency tracking

Testing

Unit Tests: Running tests with race detection and code coverage reporting
Build Verification: Ensuring the codebase builds successfully

Release Process

When changes are merged to the main branch:

CI checks are run to validate code quality and security
If successful, a new release is automatically created with:
- Semantic versioning based on commit messages
- Binary builds for multiple platforms
- Docker image publishing to GitHub Container Registry
- Helm chart publishing to GitHub Container Registry

Name		Name	Last commit message	Last commit date
Latest commit History 133 Commits
.github		.github
_includes		_includes
_layouts		_layouts
cmd		cmd
docs		docs
helm-chart/slack-mcp-client		helm-chart/slack-mcp-client
internal		internal
.env.example		.env.example
.gitignore		.gitignore
.golangci.yml		.golangci.yml
.goreleaser.yml		.goreleaser.yml
CHANGELOG.md		CHANGELOG.md
Dockerfile		Dockerfile
Makefile		Makefile
README.md		README.md
_config.yaml		_config.yaml
docker-compose.yml		docker-compose.yml
go.mod < 8000 /div>		go.mod
go.sum		go.sum
index.md		index.md
mcp-schema.json		mcp-schema.json
mcp-servers.json.example		mcp-servers.json.example
release.config.js		release.config.js
renovate.json		renovate.json

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Slack MCP Client in Go

Overview

How It Works

Features

Installation

From Binary Release

Running Locally with Binary

RAG Setup and Usage

Quick Start with RAG

RAG Features

Custom Prompts and Assistants

System Prompts

Configuration-Based Prompts

Assistant Roles

Kubernetes Deployment with Helm

Installing from GitHub Container Registry

Prerequisites

Basic Installation

Configuration Options

Using the Docker Image from GHCR

Docker Compose for Local Testing

Setup

Docker Compose Configuration

Slack App Setup

LLM Integration

LangChain Gateway

LLM-MCP Bridge

Configuration

Switching Between Providers

Configuration

Environment Variables

MCP Server Configuration

Slack-Formatted Output

Transport Modes

Documentation

Configuration & Setup

Development & Implementation

User Guides

Quick Links

Contributing

License

CI/CD and Releases

Continuous Integration Checks

Code Quality

Security

Testing

Release Process

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