{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://github.com/api-evangelist/krakend/blob/main/json-schema/backend.json",
  "title": "KrakenD Backend",
  "description": "A Backend defines a target service that a KrakenD endpoint connects to, including the host, URL pattern, encoding, and data manipulation settings.",
  "type": "object",
  "required": ["url_pattern"],
  "properties": {
    "host": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "description": "List of backend host URLs. Overrides the service-level host list."
    },
    "url_pattern": {
      "type": "string",
      "description": "The URL path to request on the backend. Supports parameter placeholders."
    },
    "encoding": {
      "type": "string",
      "enum": ["json", "safejson", "xml", "rss", "string", "no-op"],
      "description": "The encoding of the backend response."
    },
    "sd": {
      "type": "string",
      "enum": ["static", "dns"],
      "description": "Service discovery method. Static resolves at startup, DNS resolves per request."
    },
    "method": {
      "type": "string",
      "enum": ["GET", "POST", "PUT", "PATCH", "DELETE"],
      "description": "HTTP method to use when calling the backend. Defaults to the endpoint method."
    },
    "group": {
      "type": "string",
      "description": "Wraps the backend response under this key name for response merging."
    },
    "target": {
      "type": "string",
      "description": "Extracts a nested object from the backend response using this key."
    },
    "mapping": {
      "type": "object",
      "additionalProperties": {
        "type": "string"
      },
      "description": "Renames backend response fields. Key is original name, value is new name."
    },
    "allow": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "description": "Whitelist of fields to include from the backend response."
    },
    "deny": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "description": "Blacklist of fields to exclude from the backend response."
    },
    "is_collection": {
      "type": "boolean",
      "default": false,
      "description": "Set to true when the backend response is an array instead of an object."
    },
    "extra_config": {
      "type": "object",
      "description": "Additional component configurations keyed by namespace."
    }
  }
}