snowplow

Snowplow is a web service that plays a key role within the suite of components that make up Krateo PlatformOps.

It serves multiple purposes, primarily acting as a bridge between Krateo's custom resources and the UI. By enabling a dynamic and declarative approach to defining UI components and layouts, Snowplow ensures that the interface is interpreted and rendered seamlessly by Krateo Frontend.

Currently, Snowplow handles on-demand resolution of the RESTAction custom resource. For all other custom resources within Krateo, it delegates the task to the Kubernetes API server, which, in turn, leverages Krateo’s custom aggregation API layer to process them.

Looking ahead, Snowplow will take full responsibility for managing all custom resources beyond RESTAction, eventually eliminating the need for delegation altogether.

As of today, the overall architecture is structured as follows:

RESTAction

This document provides an overview of the RESTAction CRD and its properties to facilitate its usage within Kubernetes environments.

Overview

The RESTAction Custom Resource Definition (CRD) allows users to declaratively define calls to APIs that may depend on other API calls.

Schema spec Details

Property	Type	Description
api	array	Defines API requests to an HTTP service.
filter	string	A JQ filter that can be applied to the global response.

api Array Item Properties

A single api item defines an HTTP REST call. The invoked API must produce a JSON content type

Property	Type	Description
dependsOn	object	Defines dependencies on other APIs.
endpointRef	object	References an Endpoint object.
filter	string	A JQ expression for response processing.
headers	array of strings	Custom request headers (each header can be a JQ expression).
name	string	Unique identifier for the API request.
path	string	Request URI path (can be a JQ expression).
payload	string	Request body payload (can be a JQ expression).
verb	string	HTTP method (defaults to GET if omitted).

dependsOn Object Properties

Property	Type	Description
iterator	string	A JQ expression that returns a JSON array on which to iterate.
name	string	Name of another API on which this depends.

endpointRef Object Properties

Reference to a Kubernetes secret that describes the HTTP REST API endpoint.

Property	Type	Description
name	string	Name of the referenced object.
namespace	string	Namespace of the referenced object.

---

status Properties

The status field is an open-ended object that preserves unknown fields for storing results of all the api calls.

Examples

Some RESTAction examples can be found here. Lets check the one that query jsonplaceholder.typicode.com API:

---
apiVersion: v1
kind: Secret
type: Opaque
metadata:
  name: typicode-endpoint
  namespace: demo-system
stringData:
  server-url: https://jsonplaceholder.typicode.com
---
apiVersion: templates.krateo.io/v1
kind: RESTAction
metadata:
  name: typicode
  namespace: demo-system
spec:
  filter: "[.todos[] as $todo | .users[] | select(.id == $todo.userId) | { name: .name, id: $todo.id, title: $todo.title, completed: $todo.completed }]"
  api:
  - name: users
    path: "/users"
    endpointRef:
      name: typicode-endpoint
      namespace: demo-system
    filter: map(select(.email | endswith(".biz")))
  - name: todos
    dependsOn: 
      name: users
      iterator: .users
    path: ${ "/todos?userId=" + (.id|tostring) }
    headers:
      - ${ "X-UserID:" + (.id|tostring) }
    endpointRef:
      name: typicode-endpoint
      namespace: demo-system