sree – Best DevOps https://www.bestdevops.com Lets Learn, Do it & Share! Thats a Best DevOps!!! Fri, 04 Feb 2022 10:28:41 +0000 en-US hourly 1 https://wordpress.org/?v=7.1.1 What is Pod in kubernetes. Exaplin in 15 points with image as an example https://www.bestdevops.com/what-is-pod-in-kubernetes-exaplin-in-15-points-with-image-as-an-example-6/ Wed, 01 Sep 2021 07:32:50 +0000 https://www.bestdevops.com/?p=20566
  • Pod is the smallest execution unit in kubernetes
  • Pod is not a physical entity. it is a logical entity.
  • Pod is a group of one or more container
  • Pod will contain one main container and other sidecar containers
  • Storage and network will be shared among different containers inside a pod.
  • pod lifecycle is pending, running, succeeded or failed.
  • It will start in pending phase
  • If any primary containers starts OK, state will change to running.
  • If any containers terminated with failure state will changed to failed.
  • If a node dies, the Pods scheduled to that node are scheduled for deletion after a timeout period.
  • an ip will be assigned to each node.
  • pods can communicate each other via pod network
  • recommended model is one container per pod
    • ]]>         What are the components of Kubernetes worker and explain each component’s function? https://www.bestdevops.com/what-are-the-components-of-kubernetes-worker-and-explain-each-components-function-3/ Wed, 01 Sep 2021 06:55:35 +0000 https://www.bestdevops.com/?p=20508 1.Kubelet

    Responsible for instantiates the pod. and communicates with master.

    2.Kube-proxy

    Responsible for network management

    3.pod

    pod is a logical entity which contains one or more containers

    4.container

    Where the application is running

    ]]>         What are the components of Kubernetes master and explain each component’s function? https://www.bestdevops.com/what-are-the-components-of-kubernetes-master-and-explain-each-components-function/ Wed, 01 Sep 2021 06:40:06 +0000 https://www.bestdevops.com/?p=20487 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

    ]]>         List out number of storage/volume drivers supported by docker https://www.bestdevops.com/list-out-number-of-storage-volume-drivers-supported-by-docker-3/ Tue, 31 Aug 2021 09:42:29 +0000 https://www.bestdevops.com/?p=20444 Volume plugins
    PluginDescription
    Azure File Storage pluginLets you mount Microsoft Azure File Storage shares to Docker containers as volumes using the SMB 3.0 protocol. Learn more.
    BeeGFS Volume PluginAn open source volume plugin to create persistent volumes in a BeeGFS parallel file system.
    Blockbridge pluginA volume plugin that provides access to an extensible set of container-based persistent storage options. It supports single and multi-host Docker environments with features that include tenant isolation, automated provisioning, encryption, secure deletion, snapshots and QoS.
    Contiv Volume PluginAn open source volume plugin that provides multi-tenant, persistent, distributed storage with intent based consumption. It has support for Ceph and NFS.
    Convoy pluginA volume plugin for a variety of storage back-ends including device mapper and NFS. It’s a simple standalone executable written in Go and provides the framework to support vendor-specific extensions such as snapshots, backups and restore.
    DigitalOcean Block Storage pluginIntegrates DigitalOcean’s block storage solution into the Docker ecosystem by automatically attaching a given block storage volume to a DigitalOcean droplet and making the contents of the volume available to Docker containers running on that droplet.
    DRBD pluginA volume plugin that provides highly available storage replicated by DRBD. Data written to the docker volume is replicated in a cluster of DRBD nodes.
    Flocker pluginA volume plugin that provides multi-host portable volumes for Docker, enabling you to run databases and other stateful containers and move them around across a cluster of machines.
    Fuxi Volume PluginA volume plugin that is developed as part of the OpenStack Kuryr project and implements the Docker volume plugin API by utilizing Cinder, the OpenStack block storage service.
    gce-docker pluginA volume plugin able to attach, format and mount Google Compute persistent-disks.
    GlusterFS pluginA volume plugin that provides multi-host volumes management for Docker using GlusterFS.
    Horcrux Volume PluginA volume plugin that allows on-demand, version controlled access to your data. Horcrux is an open-source plugin, written in Go, and supports SCP, Minio and Amazon S3.
    HPE 3Par Volume PluginA volume plugin that supports HPE 3Par and StoreVirtual iSCSI storage arrays.
    Infinit volume pluginA volume plugin that makes it easy to mount and manage Infinit volumes using Docker.
    IPFS Volume PluginAn open source volume plugin that allows using an ipfs filesystem as a volume.
    Keywhiz pluginA plugin that provides credentials and secret management using Keywhiz as a central repository.
    Local Persist PluginA volume plugin that extends the default local driver’s functionality by allowing you specify a mountpoint anywhere on the host, which enables the files to always persist, even if the volume is removed via docker volume rm.
    NetApp Plugin (nDVP)A volume plugin that provides direct integration with the Docker ecosystem for the NetApp storage portfolio. The nDVP package supports the provisioning and management of storage resources from the storage platform to Docker hosts, with a robust framework for adding additional platforms in the future.
    Netshare pluginA volume plugin that provides volume management for NFS 3/4, AWS EFS and CIFS file systems.
    Nimble Storage Volume PluginA volume plug-in that integrates with Nimble Storage Unified Flash Fabric arrays. The plug-in abstracts array volume capabilities to the Docker administrator to allow self-provisioning of secure multi-tenant volumes and clones.
    OpenStorage PluginA cluster-aware volume plugin that provides volume management for file and block storage solutions. It implements a vendor neutral specification for implementing extensions such as CoS, encryption, and snapshots. It has example drivers based on FUSE, NFS, NBD and EBS to name a few.
    Portworx Volume PluginA volume plugin that turns any server into a scale-out converged compute/storage node, providing container granular storage and highly available volumes across any node, using a shared-nothing storage backend that works with any docker scheduler.
    Quobyte Volume PluginA volume plugin that connects Docker to Quobyte’s data center file system, a general-purpose scalable and fault-tolerant storage platform.
    REX-Ray pluginA volume plugin which is written in Go and provides advanced storage functionality for many platforms including VirtualBox, EC2, Google Compute Engine, OpenStack, and EMC.
    Virtuozzo Storage and Ploop pluginA volume plugin with support for Virtuozzo Storage distributed cloud file system as well as ploop devices.
    VMware vSphere Storage PluginDocker Volume Driver for vSphere enables customers to address persistent storage requirements for Docker containers in vSphere environment
    ]]>         What is Storage Driver and types of Storage Driver? Explained with Images. https://www.bestdevops.com/what-is-storage-driver-and-types-of-storage-driver-explained-with-images-9/ Tue, 31 Aug 2021 06:04:01 +0000 https://www.bestdevops.com/?p=20244 Storage driver is a software that allows you to write data to the writable layer of your Docker container.

    Types of storage driver

    • overlay2 – This is the preferred storage driver for all Linux distributions
    • aufs – Preferred driver for earlier versions of Docker, when running on an earlier version of Ubuntu.
    • devicemapper – Was the recommended driver for earlier versions of Centos and RHEL. Current versions support overlay2, which is the recommended driver.
    • btrfs – Used if this is the backing file system
    • zfs – Used if this is the backing file system
    • vfs – Used for testing purposes only.

    We can identify the Storage driver using below command

    docker info | grep “Storage Driver”
    Storage Driver: overlay2

    ]]>         Create one Image which have base as centos and with git – ntp – httpd https://www.bestdevops.com/create-one-image-which-have-base-as-centos-and-with-git-ntp-httpd-7/ Tue, 31 Aug 2021 06:02:05 +0000 https://www.bestdevops.com/?p=20226 Created an image

    docker run –name sree -itd centos
    b50dcbcba771a111bf7c0b9a08eb4f14acfb83c666b2d5f8afbc13a7afc0748e
    root@ip-172-31-28-155:/home/ubuntu# docker ps|grep sree
    b50dcbcba771 centos “/bin/bash” 15 seconds ago Up 14 se conds sree
    root@ip-172-31-28-155:/home/ubuntu# docker attach sree
    yum install git -y
    yum install httpd
    docker commit -a”sreerekha” -m”ce-git-httpd -sree” sree ce-git-httpd-sree

    docker images
    REPOSITORY TAG IMAGE ID CREATED SIZE
    ce-git-httpd-sree latest b50885a6b058 19 seconds ago 346MB

    docker run –name rekha -itd ce-git-httpd-sree
    0d9262edc8ec86f142dc3fcb0b78cd1b923f9003ca022aa4a68b258bf6b0efc9
    root@ip-172-31-28-155:/home/ubuntu# docker ps|grep rekha
    0d9262edc8ec ce-git-httpd-sree “/bin/bash” 17 seconds ago Up 16 seconds rekha

    docker exec rekha git –version
    git version 2.27.0

    ]]>         What is Docker Images and Explain in 10 bullet lines? https://www.bestdevops.com/what-is-docker-images-and-explain-in-10-bullet-lines-2/ Tue, 31 Aug 2021 05:56:41 +0000 https://www.bestdevops.com/?p=20269 1.Docker Image is like a template from which we can create docker containers

    2.Docker images have multiple layers

    3.Writable layer is only the upper layer which will be created when we are creating a container

    4.Docker images get stored in public or private repositories

    5.Docker images can be created either by manually or using docker file

    6.The read-only layers of an image can be shared between any container started from the same image.

    7.Size is the size used by writable layer. virtual size is size + size of container

    8.Docker image is a collection of filesystem which contains rootfs, userfs and appfs. but it doesn’t contains bootfs.

    9.using docker image inspect command we can get the details of docker image.

    10. Docker images are immutable. We can’t change it.

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