Altinity MCP Server

A Model Context Protocol (MCP) server that provides tools for interacting with ClickHouse® databases. This server enables AI assistants and other MCP clients to query, analyze, and interact with ClickHouse® databases through a standardized protocol.

Features

• Multiple Transport Options: Support for STDIO, HTTP, and Server-Sent Events (SSE) transports
• Stateless MCP Protocol: The HTTP transport serves the stateless MCP protocol (spec revision 2026-07-28) — no session affinity required, safe to run behind round-robin load balancers; older clients transparently negotiate down to 2025-11-25 and earlier
• OAuth 2.0 Authorization: Broker OAuth flows from MCP clients against any OIDC provider; auto-detects Bearer vs Basic auth for ClickHouse (see OAuth 2.0 Documentation)
• JWE Authentication: Optional JWE-based authentication with encryption for secure database access
• TLS Support: Full TLS encryption support for both ClickHouse® connections and MCP server endpoints
• Comprehensive Tools: Built-in tools for listing tables, describing schemas, and executing queries
• Dynamic Tools: Automatically generate MCP tools from ClickHouse® views and tables (see Tools Documentation)
• Resource Templates: Dynamic resource discovery for database schemas and table information
• Query Prompts: AI-assisted query building and optimization prompts
• Configuration Management: Flexible configuration via files, environment variables, or CLI flags
• Hot Reload: Dynamic configuration reloading without server restart

Table of Contents

• Quick Start
• Integration Guide
• Installation & Deployment
• Configuration
• Available Tools
• Available Resources
• Available Prompts
• OpenAI GPTs Integration
• OAuth 2.0 Authorization
• JWE Authentication
• TLS Configuration
• Development & Testing
• CLI Reference
• Contributing
• License
• Support

Quick Start

Using STDIO Transport (Default)

# Basic usage with default settings
./altinity-mcp --clickhouse-host localhost --clickhouse-port 8123

# With custom database and credentials
./altinity-mcp \
  --clickhouse-host clickhouse.example.com \
  --clickhouse-port 9000 \
  --clickhouse-protocol tcp \
  --clickhouse-database analytics \
  --clickhouse-username reader \
  --clickhouse-password secret123 \
  --clickhouse-limit 5000

Using HTTP Transport with OpenAPI

./altinity-mcp \
  --transport http \
  --address 0.0.0.0 \
  --port 8080 \
  --clickhouse-host localhost \
  --openapi http

Using SSE Transport with JWE Authentication and OpenAPI

./altinity-mcp \
  --transport sse \
  --port 8080 \
  --allow-jwe-auth \
  --jwe-secret-key "your-jwe-encryption-secret" \
  --jwt-secret-key "your-jwt-signing-secret" \
  --clickhouse-host localhost \
  --openapi http

Integration Guide

For detailed instructions on integrating Altinity MCP with various AI tools and platforms, see our Integration Guide.

Installation & Deployment

Using Docker

docker run -it --rm ghcr.io/altinity/altinity-mcp:latest --clickhouse-host clickhouse

Kubernetes with Helm

From OCI helm registry (recommended)

# Install from OCI registry
helm install altinity-mcp oci://ghcr.io/altinity/altinity-mcp/helm/altinity-mcp \
  --set config.clickhouse.host=clickhouse.example.com \
  --set config.clickhouse.database=default \
  --set config.clickhouse.limit=5000

From local helm chart

git clone https://github.com/Altinity/altinity-mcp
cd altinity-mcp
helm install altinity-mcp ./helm/altinity-mcp \
  --set config.clickhouse.host=clickhouse-service \
  --set config.clickhouse.database=analytics \
  --set config.server.transport=http \
  --set config.server.port=8080

From a tag-published GHCR image

helm install altinity-mcp oci://ghcr.io/altinity/altinity-mcp/helm/altinity-mcp \
  --set image.tag=<tag-or-sha-tag> \
  --set config.clickhouse.host=clickhouse.example.com \
  --set config.clickhouse.database=default

For detailed Helm chart configuration options, see Helm Chart README.

Docker Compose

version: '3.8'
services:
  altinity-mcp:
    build: .
    ports:
      - "8080:8080"
    environment:
      - CLICKHOUSE_HOST=clickhouse
      - MCP_TRANSPORT=http
      - MCP_PORT=8080
    depends_on:
      - clickhouse
    entrypoint: ["/bin/sh", "-c", "/bin/altinity-mcp"]
  
  clickhouse:
    image: clickhouse/clickhouse-server:latest
    ports:
      - "8123:8123"

With installed golang

go install github.com/altinity/altinity-mcp/cmd/altinity-mcp@latest
$(go env GOPATH)/bin/altinity-mcp --help

From Source

git clone https://github.com/altinity/altinity-mcp.git
cd altinity-mcp
go build -o altinity-mcp ./cmd/altinity-mcp

Configuration

Configuration File

Create a YAML or JSON configuration file:

# config.yaml
clickhouse:
  host: "localhost"
  # Optional TCP destination override. The logical host above remains the
  # HTTP Host header and TLS SNI/certificate verification name.
  connect_host: ""
  port: 8123
  database: "default"
  username: "default"
  password: ""
  protocol: "http"
  read_only: false
  max_execution_time: 600
  tls:
    enabled: false
    ca_cert: ""
    client_cert: ""
    client_key: ""
    insecure_skip_verify: false

server:
  transport: "stdio"
  address: "0.0.0.0"
  port: 8080
  tls:
    enabled: false
    cert_file: ""
    key_file: ""
    ca_cert: ""
  jwt:
    enabled: false
    secret_key: ""
  openapi:
    enabled: false
    tls: false
  metrics:
    enabled: false
  dynamic_tools:
    - regexp: "mydb\\..*"
      prefix: "db_"
    - name: "get_user_data"
      regexp: "users\\.user_info_view"

logging:
  level: "info"

When connect_host is set, it takes precedence over HTTP_PROXY and HTTPS_PROXY for ClickHouse HTTP connections so the configured address is always the TCP destination. Environment proxy behavior is unchanged when connect_host is empty.

Note: For detailed information about dynamic tools configuration, see the Tools Documentation.

Use the configuration file:

./altinity-mcp --config config.yaml

Environment Variables

Every configuration field with a flag: tag in pkg/config/config.go is settable via CLI flag or env var. The CLI flag and env-var name are listed in the field's flag: and env: tags. altinity-mcp --help prints the full surface.

Common examples:

export CLICKHOUSE_HOST=localhost
export CLICKHOUSE_PORT=8123
export CLICKHOUSE_DATABASE=analytics
export CLICKHOUSE_LIMIT=5000
export MCP_TRANSPORT=http
export MCP_PORT=8080
export MCP_METRICS_ENABLED=true
export LOG_LEVEL=debug

# OAuth — env-var injection lets operators pull secrets from a Kubernetes
# Secret via `valueFrom.secretKeyRef` instead of committing them to YAML.
export MCP_OAUTH_ENABLED=true
export MCP_OAUTH_BROKER=true
export MCP_OAUTH_ISSUER=https://accounts.example.com
export MCP_OAUTH_SIGNING_SECRET=...

./altinity-mcp

Special flags that don't follow this pattern: --config (config file path), --config-reload-time, --openapi (one flag → two struct fields). See altinity-mcp --help.

Prometheus metrics

HTTP and SSE transports (including JWE and multicluster modes) expose /metrics when server.metrics.enabled, MCP_METRICS_ENABLED, or --metrics-enabled is true. Metrics are disabled by default, and a disabled server is a true no-op: no /metrics route, no request middleware, no query instrumentation, and no collectors registered.

server.metrics.enabled is restart-only. A config reload that changes it logs a warning and keeps the running value, because the route and middleware are bound when the HTTP server starts.

The endpoint serves the standard Go runtime and process collectors plus:

Metric	Type	Labels	Meaning
altinity_mcp_http_requests_total	counter	route, method, status	Requests by registered route pattern, normalized method (GET, POST, ..., other) and status class (2xx, 4xx, ...)
altinity_mcp_http_request_duration_seconds	histogram	route	End-to-end handler latency
altinity_mcp_clickhouse_queries_total	counter	kind, outcome	ClickHouse queries by select/execute and ok/error
altinity_mcp_clickhouse_query_duration_seconds	histogram	kind	ClickHouse round-trip latency
altinity_mcp_clickhouse_query_rows	histogram	kind	Rows returned by successful queries
altinity_mcp_clickhouse_query_bytes	histogram	kind	Approximate bytes returned by successful queries
altinity_mcp_blocked_clause_rejections_total	counter	clause	Queries rejected by blocked_query_clauses
altinity_mcp_clickhouse_up	gauge		1/0 from the last /health readiness ping; NaN in JWE/OAuth modes where no static credentials exist
altinity_mcp_catalog_cache_*	gauge/counter		Multicluster catalog-cache activity (multicluster mode only)

Every label is drawn from a fixed set: route labels use registered patterns rather than raw URLs (so JWE tokens never appear), methods outside the standard set collapse to other, and status codes collapse to their class.

The /metrics endpoint is unauthenticated. Restrict network access to it in the same way you would for /health.

The Helm chart uses metrics.enabled for the endpoint. Set metrics.serviceMonitor.enabled as well to create a Prometheus Operator ServiceMonitor that scrapes the existing HTTP service port. When config.server.tls.enabled is true the ServiceMonitor scrapes over https automatically; supply metrics.serviceMonitor.tlsConfig if Prometheus does not trust the server certificate.

Available Tools

execute_query

Executes SQL queries against ClickHouse® with optional result limiting.

MCP tool safety annotations:

• When the server runs with --read-only, execute_query is exposed as read-only.
• Otherwise execute_query is marked as potentially destructive.

Parameters:

• query (required): The SQL query to execute
• limit (optional): Maximum number of rows to return (default: server configured limit, max: 10,000)

Dynamic Tools

Dynamic tools generated from ClickHouse views are always exposed as read-only MCP tools with explicit safety hints.

View COMMENT supports either:

• A plain string description.
• A strict JSON object with top-level title, description, and annotations.

See Tools Documentation for examples and supported metadata.

Available Resources

clickhouse://schema

Provides complete schema information for the ClickHouse® database in JSON format.

clickhouse://table/{database}/{table}

Provides detailed information about a specific table including schema, sample data, and statistics.

Available Prompts

No prompts currently available

OpenAI GPTs Integration

The Altinity MCP Server supports seamless integration with OpenAI GPTs through its OpenAPI-compatible endpoints. These endpoints enable GPT assistants to perform ClickHouse® database operations directly.

OpenAI MCP/tooling references:

• Apps SDK Reference
• Define tools
• Build your MCP server
• MCP concepts / server docs

Authentication

• With JWE: Add the JWE token to either:
  1. Path parameter: /{jwe_token}/openapi/...
  2. Authorization header: Bearer {token} (alternative)
  3. x-altinity-mcp-key header (alternative)
• With OAuth: Send Authorization: Bearer {token}.
• With both: A self-contained JWE takes priority; otherwise OAuth supplies the credentials.
• With both disabled: Use server-configured ClickHouse credentials.

The exact /openapi schema route also requires authentication when either mode is enabled. Dynamic HTTP/SSE tools and OpenAPI schemas use catalogs isolated by the caller's effective credential; server credentials are never a fallback under authentication. An effective configuration change resets catalog generations and requires existing SSE clients to reconnect. Unchanged reload polls preserve sessions. See dynamic discovery.

Available Actions

1. Execute Read-only SQL Query

Path: /openapi/execute_query
Parameters:

• jwe_token (path param): JWE authentication token
• query (query param): Read-only SQL query to execute (required); writes are always rejected, even when clickhouse.read_only: false.
• limit (query param): Maximum rows to return (optional, default 1000, max 10000)

Example OpenAPI Path:

GET /{jwe_token}/openapi/execute_query?query=SELECT%20*%20FROM%20table&limit=500

clickhouse.max_query_length bounds the query in bytes and dynamic-tool JSON bodies (default 10 MiB; negative disables the limit). Oversized inputs return HTTP 413 before contacting ClickHouse. OpenAPI does not expose write_query.

Configuration Example for GPTs

{
  "openapi": "3.1.0",
  "info": {
    "title": "ClickHouse® SQL Interface",
    "version": "1.0.0"
  },
  "servers": [
    {"url": "https://your-server:8080/{token}"}
  ],
  "paths": {
    "/{jwe_token}/openapi/execute_query": {
      "get": {
        "operationId": "execute_query",
        "parameters": [
          {
            "name": "jwe_token",
            "in": "path",
            "required": true,
            "schema": {"type": "string"}
          },
          {
            "name": "query",
            "in": "query",
            "required": true,
            "schema": {"type": "string"}
          },
          {
            "name": "limit",
            "in": "query",
            "schema": {"type": "integer"}
          }
        ]
      }
    }
  }
}

Note: For Altinity Cloud deployments, use the provided endpoint URL with your organization-specific token.

Authentication and Authorization

JWE takes priority when the token carries nonempty host and username claims. A complete JWE uses its own connection fields without OAuth overrides. Partial JWE claims fall through to OAuth and cannot alter its configured endpoint. Invalid encrypted tokens are rejected.

OAuth 2.0 Authorization

The MCP server supports OAuth 2.0/OpenID Connect authentication, with Bearer tokens presented to ClickHouse or verified locally. This enables MCP clients to authenticate via an Identity Provider (Keycloak, Azure AD, Google, AWS Cognito) and use token-based ClickHouse authentication via token_processors.

OAuth headers, query settings, and role activation are isolated per request and cluster; forwarding a caller's bearer token does not change the configured ClickHouse headers or later requests.

For full setup instructions, provider-specific guides, and ClickHouse configuration, see the OAuth 2.0 Authorization Documentation.

JWE Authentication

When JWE authentication is enabled, the server expects tokens encrypted using AES Key Wrap (A256KW) and AES-GCM (A256GCM). These tokens contain ClickHouse® connection parameters:

{
  "host": "clickhouse.example.com",
  "port": 8123,
  "database": "analytics",
  "username": "user123",
  "password": "secret",
  "protocol": "http",
  "secure": "false"
}

JWE tokens are self-contained: host and username are required. An absent or empty password remains empty. Server endpoint, credentials, headers, roles, and TLS settings never fill missing claims. Only operational protocol and query settings are inherited; an omitted port defaults to 8123 (HTTP) or 9000 (TCP). Regenerate older tokens that relied on server connection defaults.

Nonempty token TLS file paths require server.jwe.tls_material_dir (--jwe-tls-material-dir, MCP_JWE_TLS_MATERIAL_DIR). Paths must remain inside that operator-controlled directory after symlink resolution. See the JWE migration and TLS allowlist guide.

The HTTP/SSE /jwe-token-generator endpoint is disabled by default. To enable administrative issuance, set server.jwe.token_generator.enabled: true and inject MCP_JWE_TOKEN_GENERATOR_ADMIN_TOKEN with at least 32 bytes. Each request requires that secret as an Authorization: Bearer token. Keep this endpoint on a trusted administrative network and exclude it from public ingress. See the generator setup and request limits.

Generate tokens using the provided utility.

go run ./cmd/jwe_auth/jwe_token_generator.go \
  --jwe-secret-key "your-jwe-encryption-secret" \
  --jwt-secret-key "your-jwt-signing-secret" \
  --host "clickhouse.example.com" \
  --port 8123 \
  --database "analytics" \
  --username "user123" \
  --password "password123" \
  --expiry 86400

More details in jwe_authentication.md

TLS Configuration

ClickHouse® TLS

./altinity-mcp \
  --clickhouse-tls \
  --clickhouse-tls-ca-cert /path/to/ca.crt \
  --clickhouse-tls-client-cert /path/to/client.crt \
  --clickhouse-tls-client-key /path/to/client.key

Server TLS

./altinity-mcp \
  --transport https \
  --server-tls \
  --server-tls-cert-file /path/to/server.crt \
  --server-tls-key-file /path/to/server.key

Development & Testing

Development workflow, build commands, test tiers, and the optional OAuth Docker e2e flow are documented in docs/development_and_testing.md.

For the full OAuth setup and ClickHouse-specific details, see the OAuth 2.0 Authorization Documentation.

CLI Reference

Global Flags

• --config: Path to configuration file (YAML or JSON)
• --log-level: Logging level (debug/info/warn/error)
• --clickhouse-limit: Default limit for query results (default: 1000)
• --openapi: Enable OpenAPI endpoints (disable/http/https) (default: disable)

ClickHouse® Flags

• --clickhouse-host: ClickHouse® server host
• --clickhouse-connect-host: Optional hostname or IP used only for the underlying TCP connection (CLICKHOUSE_CONNECT_HOST)
• --clickhouse-port: ClickHouse® server port
• --clickhouse-database: Database name
• --clickhouse-username: Username
• --clickhouse-password: Password
• --clickhouse-protocol: Protocol (http/tcp)
• --read-only: Read-only mode (prevents non-read SQL and avoids setting session variables)
• --clickhouse-max-execution-time: Query timeout in seconds
• --clickhouse-http-headers: HTTP headers for ClickHouse requests (key=value pairs)

Server Flags

• --transport: Transport type (stdio/http/sse)
• --address: Server address
• --port: Server port
• --allow-jwe-auth: Enable JWE authentication
• --jwe-secret-key: Secret key for JWE token decryption (must be 32 bytes for A256KW).
• --jwt-secret-key: Secret key for JWT signature verification
• --jwe-tls-material-dir: Directory allowlist for JWE TLS file paths (empty denies token file paths)
• --jwe-token-generator: Enable administrative JWE token issuance (default false; MCP_JWE_TOKEN_GENERATOR_ENABLED)
• --jwe-token-generator-admin-token: Admin bearer secret of at least 32 bytes (prefer MCP_JWE_TOKEN_GENERATOR_ADMIN_TOKEN secret injection)
• --jwe-token-generator-max-expiry-seconds: Maximum issued token lifetime (default 86400; MCP_JWE_TOKEN_GENERATOR_MAX_EXPIRY_SECONDS)

Commands

• version: Show version information
• test-connection: Test ClickHouse® connection

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Run the test suite
6. Submit a pull request

License

This project is licensed under the Apache License 2.0. See the LICENSE file for details.

Support

For support and questions:

• GitHub Issues: https://github.com/altinity/altinity-mcp/issues
• Email: support@altinity.com