Extraction

Config DB needs to extract few important pieces of information from the config. For example: to know the id of a config item it needs to extract the id from the scraped config. For this, it makes heavy use of JSONPath expression.

JSONPath

A JSONPath expression, similar to XPath for XML, is used to extract data from a JSON structure by specifying a path to an element(s) in a JSON structure.

Example

Below is an example of the JSONPath expression in use for the File scraper

file:
  - type: $.Config.InstanceType
    id: $.Config.InstanceId
    path:
      - my-config.json

Suppose that my-config.json file referenced in the path above contains the following JSON structure

{
  "Config": {
    "InstanceId": "i-1234567890abcdef0",
    "InstanceType": "t2.micro"
  }
}

Then, the type and id of the config item will be t2.micro and i-1234567890abcdef0 respectively.

Use cases

Some of the common use cases of JSONPath expression are

Field	Description
`id`	A static value or JSONPath expression to use as the ID for the resource.
`name`	A static value or JSONPath expression to use as the Name for the resource. Default value is the `id`.
`items`	A JSONPath expression to use to extract individual items from the resource
`type`	A static value or JSONPath expression to use as the type for the resource.
`timestampFormat`	TimestampFormat is a Go time format string used to parse timestamps in createFields and DeletedFields. If not specified, the default is `RFC3339`.
`createFields`	CreateFields is a list of JSONPath expression used to identify the created time of the config. If multiple fields are specified, the first non-empty value will be used
`deleteFields`	DeleteFields is a JSONPath expression used to identify the deleted time of the config. If multiple fields are specified, the first non-empty value will be used