Kubernetes is an opensource software developed by Google It is written in go/go lang It is self healing Auto scaling Load balancing Makes deployment quicker Has an ability to absorb changes quickly Contains a master and lot of worker nodes The work station provides the desired state to master and master make sure the desired state is maintained K8s contains pod as atomic unit.

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

Docker is having the scalability challenges and K8s can manage that Docker brings challenges on network, K8s solves that K8s is the container orchestrator tool Auto heal of containers – K8s is self/auto healing K8s runs many containers as a cluster K8s provide the desired state Auto scaling Automatic rollback Load balancing K8s can absorb changes quickly Workload placement Speed of deployment is high Infrastructure abstraction

Automated rollouts and rollbacks Storage orchestration Automatic bin packing IPv4/IPv6 dual-stack Self-healing Service discovery and load balancing Secret and configuration management Batch execution Horizontal scaling Designed for extensibility

1.API Server API Server receives the request 2. Scheduler Scheduler assigns task to worker nodes 3.Cotroller Manager Monitor the worker nodes state and report the failures. 4.etcd stores the details

Kubernetes manages 1 to many containers Load Balancing – Manages the load balance of multiple containers running with same port in one host Auto healing Keep desired state of containers Allow to view the data center as a computer by managing all containers hosted in multiple host Container orchestration Automated Rollbacks Auto Scaling – addressing scalability challenges Absorb changes quickly Workload placements Infrastructure abstraction

List out all INSTRUCTION statement of dockerfile and give one line explanationFROMMAINTAINERRUNCMDLABELEXPOSEENVADDCOPYENTRYPOINTVOLUMEUSERWORKDIRARGONBUILDSTOPSIGNALHEALTHCHECKSHELL Q2. Build all these 5 images and run container and observe the use cases of it.https://devopsschool.com/tutorial/docker/dockerfile/dockerfile-example-sample-lab.html Q3. Write a example dockerfile with 2 CMD, 2 ENTRYPOINT and 1 CMD/1ENTRYPOINT and write down a behavior of it.if ENTRYPOINT is not specified, default is /bin/sh, what is specified in CMD is passed as args.2 CMD -> last one is executedCMD echo “Hello world1”CMD echo “Hello world2”Output: Hello world2 2 ENTRYPOINT

Union mount is a type of a filesystem that can create an illusion of merging contents of several directories into one without modifying its original (physical) sources. Union mount or union filesystem is not the filesystem type, but rather a concept with many implementations. UnionFS, aufs, OverlayFS, ZFS, and Btrfs are different implementations of union file systems. Docker only needs to create thin layer on top of the image and rest of it can be shared between all the containers.

A Docker image is built up from a series of layers. Each layer represents an instruction in the image’s Dockerfile. All layers except the last one is read-only. To identify each layer separately, Layers are now identified by a digest, which takes the form algorithm:hex; for example: sha256:fc92eec5cac70b0c324cec2933cd7db1c0eae7c9e2649e42d02e77eb6da0d15f The hex element is calculated by applying the algorithm (SHA256) to a layer’s content. If the content changes, then the computed digest will also change. The image ID is also a digest,

Types of storage drivers are: overlay overlay2 aufs devicemapper fuse-overlayfs vfs btrfs Types of volume drivers are: Volumes mntfs tempfs

overlay2 Overlay2 is the preferred storage driver for all currently supported Linux distributions, and requires no extra configurations. fuse-overlayfs Preferred only for running Rootless Docker on a host that does not provide support for rootless overlay2 btrfs and zfs Allows for advanced options, such as creating “snapshots”, but require more maintenance and setup. Each of these relies on the backing filesystem being configured correctly. vfsThe vfs is intended for testing purposes, and for situations where no copy-on-write filesystem can be used. Performance of this

Docker supports several storage drivers, using a pluggable architecture. The storage driver controls how images and containers are stored and managed on your Docker host.  The Docker Engine provides the following storage drivers on Linux: overlay2 – overlay2 is the preferred storage driver for all currently supported Linux distributions, and requires no extra configuration.fuse-overlayfs – fuse-overlayfsis preferred only for running Rootless Docker on a host that does not provide support for rootless overlay2. On Ubuntu and Debian 10, the fuse-overlayfs

memory – tempfs –> exists as long as the docker is livemount – to mount to a host locationvolume – use the docker /var/lib/docker/volumes

overlay2 overlay2 is the preferred storage driver for all currently supported Linux distributions, and requires no extra configuration. fuse-overlayfs fuse-overlayfsis preferred only for running Rootless Docker on a host that does not provide support for rootless overlay2. On Ubuntu and Debian 10, the fuse-overlayfs driver does not need to be used, and overlay2 works even in rootless mode. Refer to the rootless mode documentation for details. btrfs and zfs The btrfs and zfs storage drivers allow for advanced options, such as creating “snapshots”, but require more maintenance and setup. Each of these relies on

Overlay2 – preferred storage driver for all currently supported Linux distributions, and requires no extra configuration. fuse-overlayfs – preferred only for running Rootless Docker on a host that does not provide support for rootless overlay2 btrfs and zfs – The btrfs and zfs storage drivers allow for advanced options, such as creating “snapshots”, but require more maintenance and setup. Each of these relies on the backing filesystem being configured correctly Vfs –  Intended for testing purposes, and for situations where no copy-on-write filesystem can be used. Aufs

Azure File Storage plugin BeeGFS Volume Plugin Blockbridge plugin Contiv Volume Plugin Convoy plugin DigitalOcean Block Storage plugin DRBD plugin Flocker plugin Fuxi Volume Plugin gce-docker plugin GlusterFS plugin Horcrux Volume Plugin HPE 3Par Volume Plugin Infinit volume plugin IPFS Volume Plugin Keywhiz plugin Local Persist Plugin NetApp Plugin (nDVP) Netshare plugin Nimble Storage Volume Plugin OpenStorage Plugin Portworx Volume Plugin Quobyte Volume Plugin REX-Ray plugin Virtuozzo Storage and Ploop plugin VMware vSphere Storage Plugin

overlay2 fuse-overlayfs btrfs zfs vfs aufs devicemapper overlay