Configuration Files

MockForge supports comprehensive configuration through YAML files as an alternative to environment variables. This page documents the configuration file format, options, and usage.

Configuration File Location

MockForge looks for configuration files in the following order:

Path specified by --config CLI flag
Path specified by MOCKFORGE_CONFIG_FILE environment variable
Default location: ./mockforge.yaml or ./mockforge.yml
No configuration file (uses defaults)

Basic Configuration Structure

# MockForge Configuration Example
# This file demonstrates all available configuration options

# HTTP server configuration
http:
  port: 3000
  host: "0.0.0.0"
  openapi_spec: "examples/openapi-demo.json"
  cors_enabled: true
  request_timeout_secs: 30
  request_validation: "enforce"
  aggregate_validation_errors: true
  validate_responses: false
  response_template_expand: true
  skip_admin_validation: true

# WebSocket server configuration
websocket:
  port: 3001
  host: "0.0.0.0"
  replay_file: "examples/ws-demo.jsonl"
  connection_timeout_secs: 300

# gRPC server configuration
grpc:
  port: 50051
  host: "0.0.0.0"

# Admin UI configuration
admin:
  enabled: true
  port: 8080
  host: "127.0.0.1"
  mount_path: null
  api_enabled: true

# Core MockForge configuration
core:
  latency_enabled: true
  failures_enabled: false

# Logging configuration
logging:
  level: "info"
  json_format: false
  file_path: null
  max_file_size_mb: 10
  max_files: 5

# Data generation configuration
data:
  default_rows: 100
  default_format: "json"
  locale: "en"

HTTP Server Configuration

Basic Settings

http:
  port: 3000                    # Server port
  host: "0.0.0.0"              # Bind address (0.0.0.0 for all interfaces)
  cors_enabled: true           # Enable CORS headers
  request_timeout_secs: 30     # Request timeout in seconds

OpenAPI Integration

http:
  openapi_spec: "path/to/spec.json"  # Path to OpenAPI specification
  # Alternative: use URL
  openapi_spec: "https://example.com/api-spec.yaml"

Validation and Response Handling

http:
  request_validation: "enforce"      # off|warn|enforce
  aggregate_validation_errors: true  # Combine multiple errors
  validate_responses: false          # Validate generated responses
  response_template_expand: true     # Enable {{uuid}}, {{now}} etc.
  skip_admin_validation: true        # Skip validation for admin endpoints

Validation Overrides

http:
  validation_overrides:
    "POST /users/{id}": "warn"      # Override validation level per endpoint
    "GET /internal/health": "off"  # Skip validation for specific endpoints

WebSocket Server Configuration

websocket:
  port: 3001                          # Server port
  host: "0.0.0.0"                    # Bind address
  replay_file: "path/to/replay.jsonl" # WebSocket replay file
  connection_timeout_secs: 300       # Connection timeout in seconds

gRPC Server Configuration

grpc:
  port: 50051       # Server port
  host: "0.0.0.0"  # Bind address
  proto_dir: null  # Directory containing .proto files
  tls: null        # TLS configuration (optional)

Admin UI Configuration

Standalone Mode (Default)

admin:
  enabled: true
  port: 8080
  host: "127.0.0.1"
  api_enabled: true

Embedded Mode

admin:
  enabled: true
  mount_path: "/admin"  # Mount under HTTP server
  api_enabled: true     # Enable API endpoints
  # Note: port/host ignored when mount_path is set

Core Configuration

Latency Simulation

core:
  latency_enabled: true
  default_latency:
    base_ms: 50
    jitter_ms: 20
    distribution: "fixed"  # fixed, normal, or pareto

  # For normal distribution
  # std_dev_ms: 10.0

  # For pareto distribution
  # pareto_shape: 2.0

  min_ms: 10      # Minimum latency
  max_ms: 5000    # Maximum latency (optional)

  # Per-operation overrides
  tag_overrides:
    auth: 100
    payments: 200

Failure Injection

core:
  failures_enabled: true
  failure_config:
    global_error_rate: 0.05  # 5% global error rate

    # Default status codes for failures
    default_status_codes: [500, 502, 503, 504]

    # Per-tag error rates and status codes
    tag_configs:
      auth:
        error_rate: 0.1      # 10% error rate for auth operations
        status_codes: [401, 403]
        error_message: "Authentication failed"
      payments:
        error_rate: 0.02     # 2% error rate for payments
        status_codes: [402, 503]
        error_message: "Payment processing failed"

    # Tag filtering
    include_tags: []         # Empty means all tags included
    exclude_tags: ["health", "metrics"]  # Exclude these tags

Proxy Configuration

core:
  proxy:
    upstream_url: "http://api.example.com"
    timeout_seconds: 30

Logging Configuration

logging:
  level: "info"           # debug|info|warn|error
  json_format: false      # Use JSON format for logs
  file_path: "logs/mockforge.log"  # Optional log file
  max_file_size_mb: 10    # Rotate when file reaches this size
  max_files: 5           # Keep this many rotated log files

Data Generation Configuration

data:
  default_rows: 100       # Default number of rows to generate
  default_format: "json"  # Default output format
  locale: "en"           # Locale for generated data

  # Custom faker templates
  templates:
    custom_user:
      name: "{{faker.name}}"
      email: "{{faker.email}}"
      department: "{{faker.word}}"

  # RAG (Retrieval-Augmented Generation) configuration
  rag:
    enabled: false
    api_endpoint: null
    api_key: null
    model: null
    context_window: 4000

Advanced Configuration

Request/Response Overrides

# YAML patch overrides for requests/responses
overrides:
  - targets: ["operation:getUser"]     # Target specific operations
    patch:
      - op: add
        path: /metadata/requestId
        value: "{{uuid}}"
      - op: replace
        path: /user/createdAt
        value: "{{now}}"
      - op: add
        path: /user/score
        value: "{{rand.float}}"

  - targets: ["tag:Payments"]          # Target by tags
    patch:
      - op: replace
        path: /payment/status
        value: "FAILED"

Latency Profiles

# External latency profiles file
latency_profiles: "config/latency.yaml"

# Example latency configuration:
# operation:getUser:
#   fixed_ms: 120
#   jitter_ms: 80
#   fail_p: 0.0
#
# tag:Payments:
#   fixed_ms: 200
#   jitter_ms: 300
#   fail_p: 0.05
#   fail_status: 503

Configuration Examples

Development Configuration

# Development setup with debugging and fast responses
http:
  port: 3000
  response_template_expand: true
  request_validation: "warn"

admin:
  enabled: true
  port: 8080

core:
  latency_enabled: false  # Disable latency for faster development

logging:
  level: "debug"
  json_format: false

Testing Configuration

# Testing setup with deterministic responses
http:
  port: 3000
  response_template_expand: false  # Disable random tokens for determinism

core:
  latency_enabled: false

data:
  rag:
    enabled: false  # Disable RAG for consistent test data

Production Configuration

# Production setup with monitoring and reliability
http:
  port: 80
  host: "0.0.0.0"
  request_validation: "enforce"
  cors_enabled: false

admin:
  enabled: false  # Disable admin UI in production

core:
  latency_enabled: true
  failures_enabled: false

logging:
  level: "warn"
  json_format: true
  file_path: "/var/log/mockforge.log"

Configuration File Validation

MockForge validates configuration files at startup. Common issues:

Invalid YAML syntax - Check indentation and quotes
Missing required fields - Some fields like request_timeout_secs are required
Invalid file paths - Ensure OpenAPI spec and replay files exist
Port conflicts - Choose unique ports for each service

Configuration Precedence

Configuration values are resolved in this priority order:

CLI flags (highest priority)
Environment variables
Configuration file
Default values (lowest priority)

This allows you to override specific values without changing your configuration file.

Hot Reloading

Configuration changes require a server restart to take effect. For development, you can use:

# Watch for changes and auto-restart
cargo watch -x "run -p mockforge-cli -- serve --config config.yaml"

For more information on environment variables, see the Environment Variables documentation.

MockForge Documentation