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sigyl.yaml Reference

The sigyl.yaml file defines the configuration for MCP-compatible servers and is used for deployment, integration, and registry purposes. This document describes all supported fields, their types, requirements, and best practices for formatting secrets and parameters.

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Top-Level Structure

runtime: node
language: typescript

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Field Reference

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runtime (required)

  • Type: string (node | container)
  • Description: Specifies the runtime environment. Use node for Node.js servers, container for custom Docker containers.

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language (optional, node only)

  • Type: string (typescript | javascript)
  • Description: Source language for Node.js runtime. Defaults to javascript if omitted.

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entryPoint (optional)

  • Type: string
  • Description: Entry file for the server. Defaults to server.js.

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startCommand (optional)

  • Type: object
  • Fields:
    • type (required): Must be http.
    • configSchema (optional): JSON Schema describing required/optional secrets/config parameters. See Secrets & Config.
    • exampleConfig (optional): Example configuration for quickstart.

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build (optional, container only)

  • Type: object
  • Fields:
    • dockerfile (optional): Path to Dockerfile (default: Dockerfile).
    • dockerBuildPath (optional): Build context directory (default: .).

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env (optional)

  • Type: object
  • Description: Environment variables to set at runtime. Common values:
    • NODE_ENV: production
    • MCP_TRANSPORT: http
    • MCP_ENDPOINT: /mcp

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Secrets & Config

Secrets and configuration parameters are defined in the configSchema field under startCommand. This uses standard JSON Schema, with the following conventions:
  • properties: Each key is the parameter name (e.g., apiKey, temperature).
  • type: Data type (string, number, boolean).
  • description: Human-readable description.
  • default: (optional) Default value.
  • enum: (optional) Allowed values.
  • required: List of required parameter names.

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Best Practices

  • Omit title fields in parameter definitions. Use the parameter name as the display label.
  • Use description for human-readable help.
  • Use required to specify which parameters are mandatory.
  • Use enum for parameters with a fixed set of allowed values.
  • Keep secrets and sensitive config in configSchema and reference them in your code as environment variables or config values.

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Validation

  • The backend will validate your sigyl.yaml using a strict schema. See SigylConfigSchema for details.
  • Invalid or missing required fields will block deployment.