engine

Documentation

Overview

Package engine holds code that drive the engine of Kusion.

Kusion Engine is a middle layer between Intent and the actual infrastructure. The major function of this engine is to parse the Intent and to turn all actual infra resources into the desired state described in the Intent and almost all operations from the command line will invoke this engine to finish their jobs.

It consists of 3 parts:

1. Operation Engine: this part is the entrypoint of the whole Kusion Engine and is responsible for kusion basic operations like Preview, Apply, Destroy, etc. The main workflow of this part is to parse resources in the Intent, figure out which resource should be modified according to specified operation type, and execute this operation to the real infra resources. During this workflow, the following two parts will be involved.

2. Runtime: it is an interface between the actual infrastructure and Kusion. All operations that trying to manipulate a resource should be delegated to one Runtime to make this operation effect in the actual infrastructure

3. State: state is a record of an operation's result. It is often used as a datasource for 3-way merge/diff in operations like Apply or Preview

Let's get operation Preview as an example to demonstrate how the three parts cooperate in an actual operation.

                 +-------------+
                 |  Operation  |
                 |  Preview    |
                 +-------------+
                        |
                        |
                 +-------------+
                 |  Operation  |
       +---------|  Engine     |----------+
       |         +-------------+          |
       |                                  |
+-------------+                    +-------------+
|   State     |                    |   Runtime   |
+-------------+                    +-------------+

1. `Operation Engine` parses resources in Intent and converts them into a DAG

2. Walk this DAG:

1. Get the latest `State` from the actual infra by the `Runtime`
2. Get the last operation `State` from the `Release` storage medium

3. Merge/Diff three states: desired state described in Intent, live state from `Runtime` and prior state from `State` storage medium, and return the diff result to the console

Index

• Constants
• func BuildID(apiVersion, kind, namespace, name string) string
• func BuildIDForKubernetes(o *unstructured.Unstructured) string
• type ContextKey

Constants

const Separator = ":"

const (
	// WatchChannel is used to inject a channel into the runtime operation to
	// assist in watching the changes of the resources during the operation process.
	WatchChannel = ContextKey("WatchChannel")
)

Functions

func BuildID

func BuildID(apiVersion, kind, namespace, name string) string

func BuildIDForKubernetes

func BuildIDForKubernetes(o *unstructured.Unstructured) string

Types

type ContextKey

type ContextKey string

ContextKey is used to represent the key associated with the information injected into the function context.