Settings View Source Middleware (K8s.Middleware)

K8s.Middleware is associated to a K8s.Conn. By default the following K8s.Middleware.Stack is associated to all connections:

• K8s.Middleware.Request.Initialize
• K8s.Middleware.Request.EncodeBody

changing-a-connection-s-middleware

Changing a Connection's Middleware

Given a registered K8s.Conn named "foo" the following example will add ExampleMiddleware to the end of the middleware stack

{:ok, conn} = K8s.Conn.from_service_account()
new_stack = K8s.Middleware.Stack{request: [MyFirstMiddleware, MySecondMiddleware]}
conn_with_new_middleware = %K8s.Conn{conn | middleware: new_stack}

writing-middleware

Writing Middleware

request-middleware

Request Middleware

K8s.Middleware.Request is a behaviour and struct for encapsulating requests processed by the middleware stack.

Middleware is expected to return {:ok, %Request{}} to continue processing or {:error, :my_error} to halt. The error in the error tuple can be an atom or a struct. It will automatically be wrapped in K8s.Middleware.Error during processing.

To implement a piece of middleware, you need to define a function call/1 that accepts a K8s.Middleware.Request.

The example below will automatically add labels to all :post requests.

def call(%Request{method: :post, body: body} = req) do
  metadata = Map.get(body, "metadata", %{})
  metadata_with_labels = Map.put(metadata, "labels", %{"env" => "prod"})
  updated_body = Map.put(body, "metadata", metadata_with_labels)

  request_with_labels = %Request{req | body: updated_body}
  {:ok, request_with_labels}
end

response-middleware

Response Middleware

Response middleware has not been implemented at this time.