docker-compose/compose/schema.json

{
  "$schema": "http://json-schema.org/draft-04/schema#",

  "type": "object",

  "patternProperties": {
    "^[a-zA-Z0-9._-]+$": {
      "$ref": "#/definitions/service"
    }
  },

  "definitions": {
    "service": {
      "type": "object",

      "properties": {
        "build": {"type": "string"},
        "env_file": {"$ref": "#/definitions/string_or_list"},
        "environment": {
          "oneOf": [
            {"type": "object"},
            {"type": "array", "items": {"type": "string"}, "uniqueItems": true}
          ]
        },
        "image": {"type": "string"},
        "mem_limit": {"type": "number"},
        "memswap_limit": {"type": "number"},

        "extends": {
          "type": "object",

          "properties": {
            "service": {"type": "string"},
            "file": {"type": "string"}
          },
          "required": ["service"],
          "additionalProperties": false
        }

      },

      "anyOf": [
        {
          "required": ["build"],
          "not": {"required": ["image"]}
        },
        {
          "required": ["image"],
          "not": {"required": ["build"]}
        },
        {
          "required": ["extends"],
          "not": {"required": ["build", "image"]}
        }
      ],

      "dependencies": {
        "memswap_limit": ["mem_limit"]
      }

    },

    "string_or_list": {
      "oneOf": [
        {"type": "string"},
        {"$ref": "#/definitions/list_of_strings"}
      ]
    },

    "list_of_strings": {
      "type": "array",
      "items": {"type": "string"},
      "uniqueItems": true
    }

  },

  "additionalProperties": false
}