Update README.md

Kubernetes/concepts/README.md

@@ -9,6 +9,8 @@
 2. Controller - manager
   - Node Controller
   - Replication controller
+  - namespace controller,job controller, endpoint controller
+
 ## Node Controller
 - continuously watches the status of the nodes
 - takes actions to remediate situation
@@ -19,5 +21,32 @@
 ## Replication controller
 - It is responsible for monitoring the state of replica set and ensuring the desired number of pods are available at all time.
 
-- 
-3. 
+
+3.  Kubeapiserver
+  - Exposes kubernetes api. It's a frontend for kubernetes control plane
+
+4. ETCD
+  -  key-value store used as kubernetes database for storing all cluster data
+  - It stores the state of the cluster
+  - Api server communicates with the ETCD data store to provide and store the important information.
+
+5. Cloud control manager
+  - Links kubernetes cluster into cloud provider's APIs such as Node controller for determining if node (instance) is deleted in the cloud.
+  - Integrate ALB and NLB with the kuberenetes
+
+
+## Data plane components
+
+1. Nodes
+   - This are just virtual machines that run the pods
+
+2. Kubelet
+   - It's an agent which communicates with the container runtime and make the pods run in the nodes
+   - It reports pod failures to the kube-apiserver
+
+3. kube-proxy
+   - It enables network communication between the pods
+   - Also help exposing pods using services
+4. container runtime
+   - responsible for running containers
+   - k8s supports containerD, crio and other container runtimes like rocket