FastMCP Server

Helm chart for deploying FastMCP Server on Kubernetes — a MCP (Model Context Protocol) server that dynamically loads tools, resources, prompts, and knowledge bases from multiple sources.

Key Features

Multi-source loading — tools, resources, prompts, and knowledge from inline ConfigMaps, S3-compatible storage (AWS S3, MinIO, R2), Git repositories, or OCI artifacts
Merge precedence — Inline (highest) > S3 > Git > OCI (lowest) — override remote tools locally without touching the upstream source
Bearer, JWT, and multi-auth — configure one auth mode or combine multiple providers through FastMCP
Knowledge base support — serve Markdown files as MCP resources for RAG and context injection
Extra pip packages — install additional Python packages at startup before loading tools
Tool metadata — optional __tags__, __timeout__, __annotations_mcp__ module variables for tool categorization and behavior hints
Resource templates — parameterized URIs like users://{user_id}/profile for dynamic resources
Multiple resources per file — RESOURCES dict maps multiple URIs to handler functions
Error masking — hide internal error details from clients via MCP_MASK_ERROR_DETAILS
Duplicate handling — control behavior when tools share names via MCP_ON_DUPLICATE_TOOLS
Built-in Web UI — dashboard at /ui with tools/resources/prompts explorer (Alpine.js + Tailwind CDN)
Prometheus metrics — tool call counts, durations, errors, source sync status at /metrics
Structured JSON logging — LOG_FORMAT=json for Loki, ELK, CloudWatch, Datadog
Dedicated health endpoints — /healthz (liveness), /readyz (readiness), /startupz (startup)
Diagnostic endpoint — GET /debug/info with full server introspection
Init container pattern — pre-sync sources before server starts via initSync.enabled
Strict loading — MCP_STRICT_LOADING=true fails on boot if any tool/resource has errors
Hot reload — automatic tool/resource reload on filesystem changes via MCP_HOT_RELOAD=true
Periodic sync — poll S3/Git sources for changes at configurable intervals
Webhook reload — POST /reload endpoint for CI/CD-triggered reloads
OCI artifact source — pull tool bundles from OCI registries via ORAS with optional registry credentials
Selective sync — include/exclude glob patterns for source filtering
Gateway mode — compose multiple MCP servers via MCP_MODE=gateway and MCP_MOUNT_SERVERS
Tag visibility — enable/disable tools by tags with MCP_ENABLE_TAGS and MCP_DISABLE_TAGS
Multi-auth — combine bearer + JWT providers via MCP_AUTH_PROVIDERS
Tool-level scopes — __required_scopes__ module variable for authorization
Context integration — tools can use ctx: Context for progress, logging, sampling, elicitation, and session state
Rate limiting — __rate_limit__ module variable or MCP_RATE_LIMIT_DEFAULT env var (sliding window)
Caching — __cache_ttl__ module variable for idempotent tool result caching
Tool sandboxing — __max_memory_mb__ and __max_output_size_kb__ resource limits per tool
PodDisruptionBudget — pdb.enabled for zero-downtime rolling updates
HorizontalPodAutoscaler — autoscaling.enabled for auto-scaling based on CPU/memory
Security — Trivy vulnerability scan, CycloneDX SBOM, Cosign keyless signing, SLSA provenance

Installation

HTTPS Repository

helm repo add helmforge https://repo.helmforge.dev
helm repo update
helm install fastmcp-server helmforge/fastmcp-server

OCI Registry

helm install fastmcp-server oci://ghcr.io/helmforgedev/helm/fastmcp-server

Basic Example — Inline Tools

# values.yaml
sources:
  inline:
    tools:
      greet.py: |
        def greet(name: str) -> str:
            """Greet someone by name."""
            return f"Hello, {name}!"
      math_ops.py: |
        def add(a: float, b: float) -> float:
            """Add two numbers."""
            return a + b
        def multiply(a: float, b: float) -> float:
            """Multiply two numbers."""
            return a * b
    knowledge:
      overview.md: |
        # Product Overview
        This document provides context for the AI assistant.

S3 Source (MinIO, AWS S3, Cloudflare R2)

sources:
  s3:
    enabled: true
    endpoint: 'https://minio.example.com'
    bucket: mcp-tools
    region: us-east-1
    prefix: production
    accessKey: '<access-key>'
    secretKey: '<secret-key>'
    include:
      - 'tools/**/*.py'
      - 'knowledge/**/*.md'
    exclude:
      - '**/*.tmp'
    syncInterval: 300

Git Source

sources:
  git:
    enabled: true
    repository: 'https://github.com/your-org/mcp-tools.git'
    branch: main
    path: '' # optional subdirectory
    token: '<github-token>' # for private repos
    allowedRepositories:
      - 'https://github.com/your-org/mcp-tools.git'
    allowedBranches:
      - main
    include:
      - 'tools/**/*.py'
      - 'resources/**/*.py'
    exclude:
      - '**/private/**'
    syncInterval: 300

OCI Source

sources:
  oci:
    enabled: true
    registry: ghcr.io/your-org/mcp-bundle
    tag: '1.0.0'
    username: '<registry-user>'
    password: '<registry-token>'
    include:
      - 'tools/**/*.py'
      - 'knowledge/**/*.md'
    exclude:
      - '**/*.tmp'

Authentication

Bearer Token

auth:
  type: bearer
  bearer:
    token: my-secret-token
    # or use an existing Kubernetes secret:
    # existingSecret: my-auth-secret
    # existingSecretKey: token

JWT

auth:
  type: jwt
  jwt:
    issuer: 'https://auth.example.com'
    audience: 'mcp-server'
    jwksUri: 'https://auth.example.com/.well-known/jwks.json'

Multi-Auth and Scopes

auth:
  type: multi
  providers:
    - bearer
    - jwt
  bearer:
    existingSecret: fastmcp-auth
    existingSecretKey: token
  jwt:
    issuer: 'https://auth.example.com'
    audience: 'mcp-server'
    jwksUri: 'https://auth.example.com/.well-known/jwks.json'
    algorithm: RS256
  scopes:
    - tools:read
    - tools:execute
  requiredScopes:
    - tools:execute
  clientId: fastmcp-server
  requireHumanApprovalForDestructive: true

Gateway Mode

gateway:
  enabled: true
  mountServers:
    github:
      transport: streamable-http
      url: 'https://github-mcp.example.com/mcp'
      auth:
        type: bearer
        tokenEnv: GITHUB_MCP_TOKEN
    internal:
      transport: streamable-http
      url: 'http://internal-mcp.default.svc.cluster.local:8000/mcp'

extraEnv:
  - name: GITHUB_MCP_TOKEN
    valueFrom:
      secretKeyRef:
        name: github-mcp-auth
        key: token

Visibility and Reload

hotReload:
  enabled: true

visibility:
  mode: allowlist
  enableTags:
    - public
    - approved
  disableTags:
    - destructive

Observability

Prometheus Metrics

metrics:
  enabled: true
  serviceMonitor:
    enabled: true # requires Prometheus Operator
    interval: 30s

Metrics exposed at /metrics: tool call counts, durations, errors, source sync status, auth attempts.

Structured Logging

server:
  logFormat: json # JSON output for log aggregation

Health Endpoints

Endpoint	Type	When 200
`/healthz`	Liveness	Always (process running)
`/readyz`	Readiness	Sources synced + components loaded
`/startupz`	Startup	Full initialization complete

Diagnostics

GET /debug/info returns server version, FastMCP version, uptime, registered components, source status, auth type, and configuration.

Rate Limiting

rateLimiting:
  default: '100/min' # global default
  perTool:
    DEPLOY: '5/min' # per-tool override
    DELETE_DATA: '2/min'

Or via module-level variable:

__rate_limit__ = "5/min"

def deploy(service: str, version: str) -> str:
    """Deploy a service (rate limited)."""
    return f"Deployed {service}@{version}"

Caching

__cache_ttl__ = 300  # cache results for 5 minutes

def get_exchange_rate(currency: str) -> float:
    """Get current exchange rate (cached 5min)."""
    ...

caching:
  enabled: true # default
  maxSize: 1000 # max entries per tool

Tool Sandboxing

__max_memory_mb__ = 256
__max_output_size_kb__ = 100

def process_data(data: str) -> str:
    """Process data with resource limits."""
    ...

Autoscaling

autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

pdb:
  enabled: true
  minAvailable: 1

Key Values

Key	Default	Description
`image.repository`	`docker.io/helmforge/fastmcp-server`	Container image
`image.tag`	`0.11.0`	Image tag
`server.name`	`fastmcp-server`	Server name in MCP responses
`server.version`	`""`	Server version env; empty uses chart appVersion
`server.environment`	`dev`	Runtime environment (`MCP_ENV`)
`server.host`	`0.0.0.0`	Bind host
`server.port`	`8000`	HTTP port
`server.path`	`/mcp`	MCP endpoint path
`server.workspace`	`/app/workspace`	Runtime source workspace
`server.logFormat`	`text`	Log format: `text` or `json`
`server.strictLoading`	`false`	Fail on boot if component errors
`server.maskErrorDetails`	`""`	Override runtime error masking behavior
`server.onDuplicateTools`	`error`	Duplicate tool policy: `error`, `warn`, `replace`
`server.corsAllowedOrigins`	`[]`	Allowed CORS origins
`server.maxSourceFileSizeBytes`	`1048576`	Max source file size
`server.maxKnowledgeBytes`	`10485760`	Max knowledge file size
`server.allowedKnowledgeExtensions`	`[".md", ".txt"]`	Knowledge file extensions
`server.strategy.type`	`Recreate`	Deployment strategy
`server.revisionHistoryLimit`	`10`	Deployment revision history
`ui.enabled`	`true`	Enable Web UI at `/ui`
`metrics.enabled`	`false`	Enable Prometheus metrics at `/metrics`
`metrics.serviceMonitor.enabled`	`false`	Create ServiceMonitor when metrics are enabled
`auth.type`	`none`	Authentication: `none`, `bearer`, `jwt`, `multi`
`auth.allowNoAuth`	`false`	Explicitly allow no-auth production deployments
`auth.bearer.token`	`""`	Bearer token secret value
`auth.bearer.existingSecret`	`""`	Existing bearer token secret
`auth.jwt.issuer`	`""`	JWT issuer
`auth.jwt.audience`	`""`	JWT audience
`auth.jwt.jwksUri`	`""`	JWT JWKS URI
`auth.jwt.algorithm`	`RS256`	JWT verification algorithm
`auth.jwt.publicKeyExistingSecret`	`""`	Existing JWT public key secret
`auth.scopes`	`[]`	Advertised auth scopes
`auth.requiredScopes`	`[]`	Required request scopes
`auth.clientId`	`""`	OAuth client identifier
`auth.providers`	`[]`	Providers used by `multi` auth
`auth.reloadRequiredScopes`	`[]`	Scopes required for reload operations
`auth.requireHumanApprovalForDestructive`	`true`	Require approval metadata for destructive tools
`rateLimiting.default`	`""`	Default rate limit (e.g., `100/min`)
`caching.enabled`	`true`	Enable result caching
`sandboxing.maxMemoryMb`	`0`	Default max memory per tool (MB)
`sandboxing.maxOutputSizeKb`	`0`	Default max output per tool (KB)
`sources.blockedFileAllowlist`	`[]`	Explicit allowlist for blocked file names
`sources.inline.dir`	`/workspace/inline`	Inline ConfigMap mount directory
`sources.inline.tools`	`{}`	Inline Python tool files
`sources.inline.resources`	`{}`	Inline resource files
`sources.inline.prompts`	`{}`	Inline prompt files
`sources.inline.knowledge`	`{}`	Inline knowledge base files
`sources.s3.enabled`	`false`	Enable S3 source
`sources.s3.bucket`	`""`	S3 bucket name
`sources.s3.include`	`[]`	S3 include glob patterns
`sources.s3.exclude`	`[]`	S3 exclude glob patterns
`sources.s3.syncInterval`	`0`	S3 polling interval in seconds
`sources.git.enabled`	`false`	Enable Git source
`sources.git.repository`	`""`	Git repository HTTPS URL
`sources.git.username`	`""`	Optional Git username
`sources.git.allowedRepositories`	`[]`	Allowed Git repository URLs
`sources.git.allowedBranches`	`[]`	Allowed Git branches
`sources.git.include`	`[]`	Git include glob patterns
`sources.git.exclude`	`[]`	Git exclude glob patterns
`sources.git.syncInterval`	`0`	Git polling interval in seconds
`sources.oci.enabled`	`false`	Enable OCI artifact source
`sources.oci.registry`	`""`	OCI artifact reference
`sources.oci.tag`	`""`	OCI artifact tag; empty lets runtime decide
`sources.oci.existingSecret`	`""`	Existing OCI registry credential secret
`sources.oci.include`	`[]`	OCI include glob patterns
`sources.oci.exclude`	`[]`	OCI exclude glob patterns
`hotReload.enabled`	`false`	Enable filesystem hot reload
`gateway.enabled`	`false`	Run server in gateway mode
`gateway.mountServers`	`{}`	Gateway mount server map
`gateway.rawMountServersJson`	`""`	Raw `MCP_MOUNT_SERVERS` JSON override
`visibility.mode`	`blocklist`	Tool visibility mode
`visibility.enableTags`	`[]`	Allowlisted tags
`visibility.disableTags`	`[]`	Hidden tags
`extraPipPackages`	`[]`	Extra pip packages to install at startup
`initSync.enabled`	`false`	Run source sync as init container
`persistence.enabled`	`false`	Enable persistent workspace volume
`serviceAccount.create`	`true`	Create a dedicated Kubernetes ServiceAccount
`serviceAccount.automountServiceAccountToken`	`false`	Automount Kubernetes API token
`networkPolicy.enabled`	`false`	Create NetworkPolicy
`networkPolicy.ingress`	`[]`	Custom ingress rules; empty uses service port
`networkPolicy.egress`	`[]`	Custom egress rules; empty allows outbound sync
`autoscaling.enabled`	`false`	Enable HPA
`pdb.enabled`	`false`	Enable PodDisruptionBudget
`ingress.enabled`	`false`	Enable ingress

Operational Notes

Merge precedence is Inline > S3 > Git > OCI — if a tool with the same filename exists in multiple sources, the highest-precedence version wins
Production-like environments require an auth mode unless auth.allowNoAuth=true is set explicitly
ServiceMonitor requires metrics.enabled=true
Gateway mode requires either gateway.mountServers or gateway.rawMountServersJson
Knowledge base files are served as MCP resources at knowledge://{filename} URIs
Tools are Python files with top-level functions; resources need a RESOURCE_URI or RESOURCES module-level variable
Tools support optional metadata: __tags__ (set), __timeout__ (float), __annotations_mcp__ (dict)
Resource URIs can use {param} placeholders for dynamic templates
The extraPipPackages list installs before tools load — use it when tools import external libraries
The Web UI auto-refreshes every 15 seconds and requires no external dependencies
Init container pattern (initSync.enabled) separates source syncing from server startup for better Kubernetes readiness semantics
Default readiness requires at least one loaded tool, resource, prompt, or knowledge file