Faraday retry middleware

README.md

@@ -127,6 +127,19 @@ client = Kubeclient::Client.new(
 )
 ```
 
+### Middleware
+
+The Faraday HTTP client used by kubeclient allows configuration of custom middlewares. For example, you may want to add instrumentation, or add custom retry options. Kubeclient provides a hook for injecting these custom middlewares into the request/response chain, via `Client#configure_faraday(&block)`. This provides an access point to the `Faraday::Connection` object during initialization. As an example, the following code adds retry options to client requests:
+
+```ruby
+client = Kubeclient::Client.new('http://localhost:8080/api', 'v1')
+retry_options = { max: 2, interval: 0.05, interval_randomness: 0.5, backoff_factor: 2 }
+client.configure_faraday { |conn| conn.request(:retry, retry_options) }
+```
+
+For more examples and documentation, consult the [Faraday docs](https://lostisland.github.io/faraday/).
+Note that certain middlewares (e.g. `:raise_error`) are always included since Kubeclient is dependent on their behaviour to function correctly.
+
 #### Inside a Kubernetes cluster
 
 The [recommended way to locate the API server](https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#accessing-the-api-from-a-pod) within the pod is with the `kubernetes.default.svc` DNS name, which resolves to a Service IP which in turn will be routed to an API server.

lib/kubeclient/common.rb

@@ -99,6 +99,10 @@ def initialize_client(
       end
     end
 
+    def configure_faraday(&block)
+      @faraday_client = create_faraday_client(&block)
+    end
+
     def method_missing(method_sym, *args, &block)
       if discovery_needed?(method_sym)
         discover
@@ -313,6 +317,8 @@ def create_faraday_client(url = nil)
         if @auth_options[:username] && @auth_options[:password]
           connection.basic_auth(@auth_options[:username], @auth_options[:password])
         end
+        # hook for adding custom faraday configuration
+        yield(connection) if block_given?
         connection.use(FaradayMiddleware::FollowRedirects, limit: @http_max_redirects)
         connection.response(:raise_error)
       end

test/test_kubeclient.rb

@@ -273,6 +273,19 @@ def test_entity_list_parsed_symbolized
     assert_equal(%i[metadata spec status], response[:items].first.keys)
   end
 
+  def test_custom_faraday_config_options
+    client = Kubeclient::Client.new('http://localhost:8080/api/', 'v1')
+    expected_middlewares = [FaradayMiddleware::FollowRedirects, Faraday::Response::RaiseError]
+    expected_middlewares.each do |klass|
+      assert(client.faraday_client.builder.handlers.include?(klass))
+    end
+    client.configure_faraday { |connection| connection.use(Faraday::Request::Retry) }
+    expected_middlewares << Faraday::Request::Retry
+    expected_middlewares.each do |klass|
+      assert(client.faraday_client.builder.handlers.include?(klass))
+    end
+  end
+
   class ServiceList
     attr_reader :names