YuniKorn Scheduler

A Model Context Protocol (MCP) server that interfaces with the Apache YuniKorn Scheduler, allowing AI agents to observe and reason about Kubernetes batch workload resource management, queue hierarchies, and application states.

Screenshots

Inspecting Yunikorn tools using MCP inspector

Querying the Yunikorn scheduler via MCP using Opencode

Features

• 7 MCP Tools: Query partitions, queues, applications, nodes, user usage, and scheduler health
• 2 MCP Resources: Static data access for partitions list and node utilization
• Async HTTP: Non-blocking API calls using httpx
• Proper Error Mapping: YuniKorn HTTP errors mapped to standard MCP error responses
• Resource Awareness: Handles YuniKorn's raw bytes and millicore values
• CORS Enabled: Allows connections from any origin for browser-based MCP Inspector
• Streamable HTTP: Default transport with stdio fallback for IDE integration

Installation

uv pip install -r requirements.txt

If you are using a virtual environment, make sure it is activated first:

source .venv/bin/activate
uv pip install -r requirements.txt

Usage

Running the Server

The default transport is Streamable HTTP on port 8000:

Run locally

uv run python -m main

Run with Docker

docker run -p 8000:8000 -e YUNIKORN_BASE_URL="http://<REPLACE_ME>/ws/v1" docker.io/frenoid/yunikorn-mcp-server:latest

Command line options

Option	Description	Default
--transport	Transport protocol (stdio, streamable-http)	streamable-http
--host	Host to bind (HTTP transport only)	0.0.0.0
--port	Port to listen on (HTTP transport only)	8000
--log-level	Logging level	INFO

Examples:

# Streamable HTTP on custom port
uv run python -m main --transport streamable-http --host 127.0.0.1 --port 8080

# Stdio mode for Claude Code / IDE integration
uv run python -m main --transport stdio

Environment Variables

Variable	Description	Default
YUNIKORN_BASE_URL	Base URL of the YuniKorn REST API	http://localhost:9089/ws/v1/
TLS_INSECURE	Disable HTTPS certificate verification (true/false)	false

# Connect to a remote YuniKorn instance
YUNIKORN_BASE_URL=http://yunikorn.example.com:9089/ws/v1/ uv run python -m main

# Connect to an HTTPS endpoint with a self-signed certificate
YUNIKORN_BASE_URL=https://yunikorn.example.com:9089/ws/v1/ TLS_INSECURE=true uv run python -m main

Connecting with MCP Inspector

The Streamable HTTP endpoint is exposed at the /mcp path:

http://localhost:8000/mcp

Testing

Run the test suite against a live YuniKorn instance:

YUNIKORN_BASE_URL=http://your-yunikorn-host:9089/ws/v1/ uv run python test_server.py

To run a quick compliance check:

YUNIKORN_BASE_URL=http://your-yunikorn-host:9089/ws/v1/ uv run python test_updated_server.py

Data Format Notes

• Memory: Represented in raw bytes (64-bit signed integers).
• CPU (vcore): Represented in millicores (thousandths of a core, i.e. 1000m = 1 core).
• Other resources: No specific unit assigned.
• Active applications: The virtual "active" state represents New, Accepted, Running, Completing, and Failing statuses.
• allocationID vs uuid: uuid is deprecated. allocationID contains the same base value as uuid with a hyphen-counter suffix (e.g., -0, -1).
• allocationDelay: The difference between allocationTime and requestTime for an allocation.

API Conformance

This MCP server conforms to the Apache YuniKorn Scheduler REST API (v1.8.0). Each tool maps directly to a documented endpoint.

Tool	YuniKorn Endpoint
get_partitions	GET /ws/v1/partitions
get_partition_queues	GET /ws/v1/partition/{partitionName}/queues
get_applications_by_state	GET /ws/v1/partition/{partitionName}/applications/{state}?status={status}
inspect_application	GET /ws/v1/partition/{partitionName}/application/{appId}
get_node_details	GET /ws/v1/partition/{partitionName}/nodes or /node/{nodeId}
get_user_usage	GET /ws/v1/partition/{partitionName}/usage/users or /usage/user/{userName}
check_scheduler_health	GET /ws/v1/scheduler/healthcheck

Resources:

Resource	YuniKorn Endpoint
yunikorn://partitions/list	GET /ws/v1/partitions
yunikorn://nodes/utilization	GET /ws/v1/scheduler/node-utilizations

Error Mapping

YuniKorn HTTP Code	MCP Error
400 Bad Request	INVALID_REQUEST
404 Not Found	INVALID_REQUEST
500 Internal Server Error	INTERNAL_ERROR