schema.json

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "array",
  "items": {
    "type": "object",
    "properties": {
      "name": {
        "type": "string"
      },
      "source": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "array",
            "items": {
              "type": "string"
            },
            "uniqueItems": true
          }
        ]
      },
      "accounts": {
        "type": "array",
        "items": {
          "type": "string",
          "minLength": 12,
          "maxLength": 12
        },
        "uniqueItems": true
      },
      "type": {
        "enum": [
          "aws"
        ]
      }
    },
    "required": [
      "name",
      "accounts"
    ],
    "additionalProperties": false
  }
}