Container orchestration Manages state of container Auto healing function Auto Scaling Load balancing Easy deployment Implement the changes easily Automated rollouts and rollbacks

Kubernetes (also known as K8s) is open source software for deploying, scaling and managing containerized applications. As an orchestrator, Kubernetes handles the work of scheduling containers on a cluster and also manages the workloads to ensure they run as you intended. Features: Self-monitoring: Kubernetes checks constantly the health of nodes and containers Portable: Kubernetes offers portability, and faster, simpler deployment times.  High availability: Kubernetes addresses high availability at both the application and the infrastructure level.  Horizontal scaling: Kubernetes allows you scaling resources not only vertically

etcdIt stores the configuration information which can be used by each of the nodes in the cluster. API ServerKubernetes is an API server which provides all the operation on cluster using the API. Controller ManagerThis component is responsible for most of the collectors that regulates the state of cluster and performs a task. SchedulerThis is one of the key components of Kubernetes master. It is a service in master responsible for distributing the workload. Kubernetes – Node ComponentsFollowing are the

Kubernetes is an Orchestrator for running containers.Kubernetes provides auto scalability.Kubernetes provides load balancing.Kubernetes provides self healing feature.Kubernetes provides automated rollouts and rollbacks.Kubernetes has persistant storage.Kubernetes provides service discovery.Kubernetes has secrets and config management.Kubernetes provides automatic bin packing.Kubernetes design follows microservice architecture.

It is compose of a control plane. which in turn contain following API Server- User from outside interact with the API Server, to get access to the pod Etcd– act as the brain,, where all information about the pods are storing Scheduler- Schedules the pods, meaning if one pod down create similar copy of it

Pod — collection of containers 3.Scaling 4.Provides additional services: as well as the management of containers, Kubernetes offers security, networking and storage services 5.Storage orchestration: Kubernetes mounts and add storage system of your choice to run apps 6.Container balancing: Kubernetes always knows where to place containers, by calculating the “best location” for them

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.

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

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

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