Kubernetes HTTP Request Flow

As we learned in earlier chapters, when we run any kubectl command, the command is translated into an HTTP API request in JSON format and is sent to the API server. Then, the API server returns a response to the client, along with any requested information. The following diagram shows the API request life cycle and what happens inside the API server when it receives a request:

Figure 4.2: API server HTTP request flow

As you can see in the preceding figure, the HTTP request goes through the authentication, authorization, and admission control stages. We will take a look at each of these in the following subtopics.

Authentication

In Kubernetes, every API call needs to authenticate with the API server, regardless of whether it comes from outside the cluster, such as those made by kubectl, or a process inside the cluster, such as those made by kubelet.

When an HTTP request is sent to the API server, the API server needs to...