Configuration

OpenDaemon reads a single dmn.json file that defines service commands, dependencies, readiness checks, and optional environment files.

Config location

Default: ./dmn.json in the current working directory
Override with: --config /absolute/path/to/dmn.json

Using an absolute config path is recommended for scripts and MCP clients.

Top-level shape

{
  "version": "1.0",
  "services": {
    "service-name": {
      "command": "npm run dev"
    }
  }
}

Service fields

Field	Type	Required	Purpose
`command`	string	Yes	Command used to start the service
`depends_on`	string[]	No	Services that must start first
`ready_when`	object	No	Readiness probe configuration
`env_file`	string	No	Path to an env file loaded for this service

Readiness checks

OpenDaemon supports two readiness modes:

`log_contains`

Wait until a log line contains a pattern.

{
  "ready_when": {
    "type": "log_contains",
    "pattern": "Server listening on",
    "timeout_seconds": 60
  }
}

`url_responds`

Wait until an HTTP endpoint responds.

{
  "ready_when": {
    "type": "url_responds",
    "url": "http://localhost:3000/health"
  }
}

Legacy keys (log_contains, url_responds) are still recognized for backward compatibility.

Full example

{
  "version": "1.0",
  "services": {
    "database": {
      "command": "docker run --rm -p 5432:5432 -e POSTGRES_PASSWORD=dev postgres:15",
      "ready_when": {
        "type": "log_contains",
        "pattern": "database system is ready to accept connections",
        "timeout_seconds": 120
      }
    },
    "backend": {
      "command": "npm run dev",
      "depends_on": ["database"],
      "ready_when": {
        "type": "url_responds",
        "url": "http://localhost:3000/health"
      },
      "env_file": ".env.local"
    }
  }
}

Best practices

Prefer explicit readiness checks over fixed sleeps.
Keep dependency chains minimal and meaningful.
Use absolute --config paths in automation and MCP configs.

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