Pods are the smallest deployable units of computing that you can create and manage in Kubernetes. A Pod (as in a pod of whales or pea pod) is a group of one or more containers. A pod with multiple container is not a good practice Pods can be created using yaml or json Pod has multiple states. Running, Pending and succeeded/failed Each pod connects to common pod network Each pod is an application Pods can only be instantiated not created Service

Kubelet Kube-proxy pod container

kube-apiserver The API server is a component of the Kubernetes control plane that exposes the Kubernetes API. The API server is the front end for the Kubernetes control plane. The main implementation of a Kubernetes API server is kube-apiserver. kube-apiserver is designed to scale horizontally—that is, it scales by deploying more instances. You can run several instances of kube-apiserver and balance traffic between those instances. etcd Consistent and highly-available key value store used as Kubernetes’ backing store for all cluster data. If your

Pods 2. Master and worker nodes 3. Scalable 4. load balancer 5. Cluster 6. Containers 7. Self healing 8. Service

FROM – creates a layer from the base imageeg : FROM ubuntu:18.04 MAINTAINER – The MAINTAINER instruction allows you to set the Author field of the generated images.RUN – builds your application with makeeg : RUN make /appCMD – specifies what command to run within the containerLABEL – The LABEL instruction adds metadata to an image.EXPOSE – Informs Docker that the container listens on the specified network port(s) at runtime.ENV – The ENV instruction sets the environment variable to the

Docker pause : suspends all the running process in the specified containersDocker unpause : un suspends all the running process

Docker stop : Stop a running container (send SIGTERM, and then SIGKILL after grace period). Will try to stop it gracefully.If process is not stopped gracefully it will send a kill command after a specific grace period. Docker kill : Kill a running container (send SIGKILL, or specified signal). This will stop the main entrypoint process/program abruptly. Any pending file system changes that the main process still had in memory will be lost, so the file system might end up

Docker container is a lightweight execution environment where a user can run their applications.These are working application created from docker images and a user can start an instance of the application. All the necessary resource and packages to run an application is availble in the docker image. A container created will have all the root file system that of a linux environment f the image is of linux architecure. for eg: Below is the container started from an httpd docker