Atomic Unit of kubernetes Pod contains one or more containers A node can have multiple pods pods have few states – pending, running, succeeded/failed pods are ephemeral

docker – which builds and run the container. kubelet – A service for communication with etcd etc. kube-proxy – it is resposible for managing network. it makes the ports available to external.

etcd – It is the storage. it is key value pair. apiserver – It is the listener scheduler – it schedules, mean add new pods if necessary. controller manager – it monitors the pods always.

Monitoring the pods Add or Remove pods if necessary. Extensibility Scalability Failure discovery and handling Ip address allocation for pods

overlay2 fuse-overlayfs btrfs zfs vfs aufs devicemapper overlay

FROM -It should be the first instruction in the Dockerfile. It is used to specify our base layer from which we are creating the image. MAINTAINER – It is used to set the author. RUN – It is used to run a command in shell. CMD – It provides a default executable for a container. LABEL – It is used for putting some metadata in a container. EXPOSE – Expose a port and listens to it. ENV – Used to

docker run –name vin_centos -itd centos:latestdocker psdocker attach 083fb828fcad docker psdocker commit -a”Vineesh” -m”Updated Centos” 083fb828fcad vineesh_centos2docker imagesdocker run –name Vineesh_Centos2 -itd 32083f4af9bedocker psdocker exec a9c938de7bdb git

docker run –name vin1 -itd ubuntu:latestdocker psdocker attach e80fd4a69088docker commit –helpdocker commit -a”VIneesh” -m”Added apache” e80fd4a69088 vineesh_ubuntudocker imagesdocker psdocker exec e80fd4a69088 gitdocker imagesdocker run -itd vineesh_ubuntudocker psdocker exec acdda25da2d2 git

Images are the base of a container. Images are like classes and containers are like objects. We can create any number of containers from an image. Images can be created from Dockerfile or we can pull from registry. Images can have multiple layers. Images have root file systems , PID, USER namespace etc. Image layers are named with SHA256 algorithm.

Storage drivers are used to write to the container’s writable layer. overlay2 is the most commonly used storage driver nowadays. overlay2 is the default storage driver.

This command is used for waiting one or more containers to stop. We have to open 2 terminals. In one of them just put docker wait and in the other try to stop the same container. We can see the first terminal with docker wait is returned 0 and stopped waiting. docker wait renamed1 [Terminal1] docker stop renamed1 [Terminal2]

It is used for updating container’s configuration. A container have different configurations. We can change those configurations via docker update command. docker update –restart=on-failure:3 renamed1 In the above example we are changing the restart policy of a container.

Q1. Explain What is Docker Container with image? A container which contains our image with root file system, 1 PID, 1 NW, 1 MNT, 1 USER. Q2. What is the difference between docker stop and docker kill? docker stop and docker kill doing the same thing only the internal process have difference. Both stops a running container to an exit state. docker create –name vin6 httpddocker start vin6docker psdocker stop vin6docker ps -adocker start vin6docker pause vin6docker ps -adocker unpause

A container which contains our image with root file system, 1 PID, 1 NW, 1 USER.

Docker pause is used to pause the running container which can be resumed with unpause. But is we stop or kill we can not unpause but we can restart. docker create –name vin6 httpddocker start vin6docker psdocker stop vin6 docker ps -adocker start vin6docker pause vin6docker ps -adocker unpause vin6docker images -adocker ps -adocker stop vin6docker restart vin6docker psdocker kill vin6

docker stop and docker kill doing the same thing only the internal process have difference. Both stops a running container to an exit state. docker create –name vin6 httpddocker start vin6docker psdocker stop vin6docker ps -adocker start vin6docker pause vin6docker ps -adocker unpause vin6docker images -adocker ps -adocker stop vin6docker restart vin6docker psdocker kill vin6