API Server CustomResourceDefinitions
This article has studied the source code of the CRD part, equipped with the source code for further understanding, which can deepen the understanding and enhance related design capabilities.
ResourceConfig
Default Configuration
Enabled resource configuration and disabled version.
Extend
Enabled the selection as follows.
Runtime Support
The three are shown below.
Storage
Custom Resource Definitions
The Store is expanded as shown below.
State Transition
Landscape
SharedInformerFactory is used to create SharedIndexInformer, which will periodically use Clientset to connect to the API Extension Services of v1beta1 or v1 and notify the respective ResourceEventHandler after obtaining the status change. Here, there are still some issues that need to dig deeper:
How SharedInformerFactory distinguishes different types of resource state changes
Can ResourceEventHandler pay attention to changes in the state of different types of resources at the same time
How are resource status changes obtained
Clientset
The Clientset function is relatively simple. It encapsulates the available API Extension Services. Each RESTClient is connected to the "Loopback" address and sends requests to different services.
SharedInformerFactory
Relationship
Add Informers
Management
EstablishingController
After the EstablishingController is started, it will start a scheduled execution task. This task checks every second whether there is a new Key value in the queue. If there is, update the corresponding resource status on the Server side to Established.
The sync code is as follows.
CRD Handler
The CRD Handler registers event processing with SharedIndexInformer. When the Watch object type is Update, it may be that the state changes to the Established state and needs to be sent to the EstablingController.
When the CRD Handler processes the request, it first checks whether the cache contains the requested object, if so, returns the cached object; if not, it requests the Server and changes the cache status.
CRD Controller
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