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Jenkins (MCP)

The Jenkins MCP Server Plugin enables Holmes to interact with your Jenkins CI/CD infrastructure.

Prerequisites

  • A running Jenkins instance with the MCP Server Plugin installed
  • A Jenkins API token for authentication
  • Network connectivity from Holmes to the Jenkins MCP endpoint

Installing the Jenkins MCP Plugin:

  1. In Jenkins, go to Manage Jenkins → Plugins → Available plugins
  2. Search for "MCP Server" and install it
  3. Restart Jenkins if required

Creating a Jenkins API Token:

  1. Sign in to Jenkins
  2. Click your username in the upper-right corner → Security
  3. Under API Token, click Add new Token
  4. Enter a descriptive name and click Generate
  5. Copy the token immediately (it won't be shown again)
  6. Click Save

Encoding credentials for Basic authentication:

The Jenkins MCP server uses HTTP Basic authentication. Encode your credentials:

echo -n "username:api_token" | base64

[Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes("username:api_token"))

Store the encoded credential securely for use in the configuration below.

Configuration

Add the following to ~/.holmes/config.yaml. Create the file if it doesn't exist:

mcp_servers:
  jenkins:
    description: "Jenkins CI/CD server"
    config:
      url: "https://your-jenkins-instance/mcp-server/mcp"
      mode: streamable-http
      headers:
        Authorization: "Basic <base64_encoded_credentials>"
      verify_ssl: false  # Set to true if using valid SSL certificates
    icon_url: "https://cdn.simpleicons.org/jenkins/D24939"
    llm_instructions: |
      When investigating build failures, start with recent build status and then examine console output.
      Use pagination for large result sets to avoid token overflow.

Replace <base64_encoded_credentials> with your encoded username:api_token.

After making changes to your configuration, run: 

holmes toolset refresh

Create Kubernetes Secret:

# Encode your credentials
JENKINS_AUTH=$(echo -n "username:api_token" | base64)

# Create the secret
kubectl create secret generic jenkins-credentials \
  --from-literal=token="$JENKINS_AUTH" \
  -n <namespace>

Configure Helm Values:

# values.yaml
additionalEnvVars:
  - name: JENKINS_AUTH_TOKEN
    valueFrom:
      secretKeyRef:
        name: jenkins-credentials
        key: token

mcp_servers:
  jenkins:
    description: "Jenkins CI/CD server"
    config:
      url: "https://your-jenkins-instance/mcp-server/mcp"
      mode: streamable-http
      headers:
        Authorization: "Basic {{ env.JENKINS_AUTH_TOKEN }}"
      verify_ssl: false
    icon_url: "https://cdn.simpleicons.org/jenkins/D24939"
    llm_instructions: |
      When investigating build failures, start with recent build status and then examine console output.
      Use pagination for large result sets to avoid token overflow.

Then deploy or upgrade your Holmes installation:

helm upgrade --install holmes robusta/holmes -f values.yaml

Create Kubernetes Secret:

# Encode your credentials
JENKINS_AUTH=$(echo -n "username:api_token" | base64)

# Create the secret
kubectl create secret generic jenkins-credentials \
  --from-literal=token="$JENKINS_AUTH" \
  -n <namespace>

Configure Helm Values:

# generated_values.yaml
holmes:
  additionalEnvVars:
    - name: JENKINS_AUTH_TOKEN
      valueFrom:
        secretKeyRef:
          name: jenkins-credentials
          key: token

  mcp_servers:
    jenkins:
      description: "Jenkins CI/CD server"
      config:
        url: "https://your-jenkins-instance/mcp-server/mcp"
        mode: streamable-http
        headers:
          Authorization: "Basic {{ env.JENKINS_AUTH_TOKEN }}"
        verify_ssl: false
      icon_url: "https://cdn.simpleicons.org/jenkins/D24939"
      llm_instructions: |
        When investigating build failures, start with recent build status and then examine console output.
        Use pagination for large result sets to avoid token overflow.

Then deploy or upgrade your Robusta installation:

helm upgrade --install robusta robusta/robusta -f generated_values.yaml --set clusterName=YOUR_CLUSTER_NAME

MCP endpoint path

The Jenkins MCP server serves on /mcp-server/mcp for Streamable HTTP transport. Other available endpoints:

  • Streamable HTTP: /mcp-server/mcp (recommended)
  • SSE: /mcp-server/sse
  • Stateless: /mcp-server/stateless

Testing the Connection

holmes ask "List all Jenkins jobs"

Common Use Cases

Investigate a failed build: 

holmes ask "Why did the last build of my-app-pipeline fail?"

Check build status: 

holmes ask "What is the status of the most recent builds for the deploy-production job?"

View build logs: 

holmes ask "Show me the console output from the last failed build of backend-service"

Monitor pipeline stages: 

holmes ask "What stages failed in the latest run of the CI pipeline?"

Check queue status: 

holmes ask "Are there any builds waiting in the Jenkins queue?"

Analyze build trends: 

holmes ask "Show me the build history and success rate for the integration-tests job"

Troubleshooting

Authentication Errors

If you receive 401 or 403 errors:

  1. Verify your API token is valid and not expired
  2. Ensure the credentials are properly base64 encoded (username:token format)
  3. Check that the Jenkins user has appropriate permissions

Connection Issues

If Holmes cannot connect to Jenkins:

  1. Verify the Jenkins URL is accessible from the Holmes pod/container
  2. Check if SSL certificate verification is causing issues (verify_ssl: false for self-signed certs)
  3. Ensure the MCP Server plugin is installed and enabled in Jenkins

Plugin Not Found

If the /mcp-server/mcp endpoint returns 404:

  1. Verify the MCP Server plugin is installed in Jenkins
  2. Restart Jenkins after plugin installation
  3. Check Jenkins system logs for plugin errors

Additional Resources