Docker is an open-source tool that automates the deployment of applications inside software containers by providing an additional layer of abstraction of operating system level virtualization on Linux. Docker makes it easier to create, deploy and run applications by using containers. Containers allow a developer to package up an application with all of the libraries and dependencies, and ship it all out as one package. Docker is same as virtual machine, rather than creating a whole virtual operating system. Docker allows applications to use the same Linux kernel as the system that they are running on. This gives a significant performance boost and reduces the size of the application.<\/p>\n
Docker is preferred by many system admins and developers to maximize their creativity in an App production environment. For system admins, Docker gives flexibility and reduces the number of systems needed because of its small footprint and lower overhead.<\/p>\n
In this tutorial, We’ll learn how to install Docker on CentOS-7.<\/p>\n
##Requirements<\/p>\n
CentOS-7 64-bit configured with static IP address. Kernel version must be 3.10 at minimum.<\/p>\n
##Installing Docker<\/p>\n
It is recommended to update your system before installing docker.<\/p>\n
To update the system, Run:<\/p>\n
Docker package is not available in CentOS-7 repository. So you need to create repo for docker.<\/p>\n You can create docker repo by creating docker.repo file inside \/etc\/yum.repos.d\/ directory.<\/p>\n Add the following line:<\/p>\n After creating docker repo, run the following command to install docker.<\/p>\n Once docker has been installed, it is recommended to start docker service and set docker service to start at boot.<\/p>\n You can do this by running the following command:<\/p>\n You can check the status of Docker by running the following command:<\/p>\n Finally, you can verify that the latest version of docker is installed with the following command<\/p>\n You can see the output some thing like this:<\/p>\n ##Working With Docker<\/p>\n ###Downloading a Docker Container<\/p>\n Let\u2019s start using docker. You will need to have an image present on your host machine where the containers will exist. You can download the CentOS docker image by running the following command.<\/p>\n You can see the output some thing like this:<\/p>\n ###Running a Docker Container<\/p>\n Now, You just run one command to setup a basic CentOS container with a bash shell.<\/p>\n To run a command in new container, Run:<\/p>\n Note: -i flag attaches stdin and stdout and -t flag allocates a tty.<\/p>\n That’s it. Now you’re using a bash shell inside of a centos docker container.<\/p>\n There are many containers already available on docker website. You can found any container through a search. For example to search centos container, Run:<\/p>\n You can see the output some thing like this:<\/p>\n You can also list all available images on your system using the following command:<\/p>\n You can see the output some thing like this:<\/p>\n ##Docker basic command lines<\/p>\n Let’s start with seeing all available commands docker have.<\/p>\n You can list all available docker command by running the following command:<\/p>\n You should see the following output:<\/p>\n Run ‘docker COMMAND –help’ for more information on a command.<\/p>\n `sudo docker info`<\/p>\n Containers: 6 Running: 0 Paused: 0 Stopped: 6 Images: 22 Server Version: 1.10.0 Storage Driver: aufs Root Dir: \/var\/lib\/docker\/aufs Backing Filesystem: extfs Dirs: 35 Dirperm1 Supported: false Execution Driver: native-0.2 Logging Driver: json-file Plugins: Volume: local Network: bridge null host Kernel Version: 3.13.0-32-generic Operating System: Zorin OS 9 OSType: linux Architecture: x86_64 CPUs: 4 Total Memory: 3.746 GiB Name: Vyom-PC ID: G2NZ:3DDJ:KJFV:HC2E:HR3Y:J4JH:TX2D:EX57:K26Y:3AFH:FGKB:XEIF Username: hitjethva Registry: https:\/\/index.docker.io\/v1\/ WARNING: No swap limit support<\/p>\n `sudo docker ps`<\/p>\n CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 534544f2e924 centos “\/bin\/bash” 30 seconds ago Up 29 seconds boring_hamilton “`<\/p>\n You can also list both running and non-running containers by running the following command:<\/p>\n Sometimes container stops due to its process ending or you stopping it explicitly. In this situation you can run container again with container ID.<\/p>\n You can also stop a running container by running the following command:<\/p>\n Note: You can find container ID using If you would like to save the changes you have made with a container, use commit command to save to save it as an image.<\/p>\n This command turns your container to an image. You can roll back when your container you need.<\/p>\n If you want to attach into a running container, Docker allows you to interaction with running containers using the attach command.<\/p>\n You can use attach command with the container ID..<\/p>\n ##Stop and Delete all Containers and Images<\/p>\n To stop all running containers, Run:<\/p>\n To delete all existing containers, Run:<\/p>\n To delete all existing images, Run:<\/p>\n ##Conclusion<\/p>\n Congratulations! You now have a centos server with a Docker platform for your application development environment.<\/p>\n","protected":false},"excerpt":{"rendered":" Docker is an open-source tool that automates the deployment of applications inside software containers by providing an additional layer of abstraction of operating system level virtualization on Linux. Docker makes it easier to create, deploy and run applications by using containers. Containers allow a developer to package up an application with all of the libraries […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[82],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7260"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7260"}],"version-history":[{"count":2,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7260\/revisions"}],"predecessor-version":[{"id":7262,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7260\/revisions\/7262"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7260"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7260"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}sudo yum -y update<\/code><\/p>\nsudo nano \/etc\/yum.repos.d\/docker.repo<\/code><\/p>\n\r\n[dockerrepo]\r\nname=Docker Repository\r\nbaseurl=https:\/\/yum.dockerproject.org\/repo\/main\/centos\/7\r\nenabled=1\r\ngpgcheck=1\r\ngpgkey=https:\/\/yum.dockerproject.org\/gpg\r\n<\/code><\/pre>\nsudo yum install docker-engine<\/code><\/p>\nsudo systemctl start docker.service<\/code> sudo systemctl enable docker.service<\/code><\/p>\nsudo systemctl status docker.service<\/code><\/p>\nsudo docker version<\/code><\/p>\nClient:\r\n Version: 1.10.0\r\n API version: 1.22\r\n Go version: go1.5.3\r\n Git commit: 590d5108\r\n Built: Thu Feb 4 18:36:33 2016\r\n OS\/Arch: linux\/amd64<\/code><\/pre>\nServer:
\nVersion: 1.10.0
\nAPI version: 1.22
\nGo version: go1.5.3
\nGit commit: 590d5108
\nBuilt: Thu Feb 4 18:36:33 2016
\nOS\/Arch: linux\/amd64
\n<\/code><\/p>\nsudo docker pull centos<\/code><\/p>\nUsing default tag: latest\r\nlatest: Pulling from library\/centos<\/code><\/pre>\na3ed95caeb02: Pull complete
\n196355c4b639: Pull complete
\nDigest: sha256:381f21e4c7b3724c6f420b2bcfa6e13e47ed155192869a2a04fa10f944c78476
\nStatus: Downloaded newer image for centos:latest
\n<\/code><\/p>\nsudo docker run -i -t centos \/bin\/bash<\/code><\/p>\nsudo docker search centos<\/code><\/p>\nNAME DESCRIPTION STARS OFFICIAL AUTOMATED\r\ncentos The official build of CentOS. 2079 [OK] \r\njdeathe\/centos-ssh CentOS-6 6.7 x86_64 \/ CentOS-7 7.2.1511 x8... 19 [OK]\r\njdeathe\/centos-ssh-apache-php CentOS-6 6.7 x86_64 \/ Apache \/ PHP \/ PHP M... 14 [OK]\r\nmillion12\/centos-supervisor Base CentOS-7 with supervisord launcher, h... 10 [OK]\r\nblalor\/centos Bare-bones base CentOS 6.5 image 8 [OK]\r\nnimmis\/java-centos This is docker images of CentOS 7 with dif... 8 [OK]\r\ntorusware\/speedus-centos Always updated official CentOS docker imag... 7 [OK]\r\ncentos\/mariadb55-centos7 3 [OK]\r\nnickistre\/centos-lamp LAMP on centos setup 3 [OK]\r\nnathonfowlie\/centos-jre Latest CentOS image with the JRE pre-insta... 3 [OK]\r\nconsol\/sakuli-centos-xfce Sakuli end-2-end testing and monitoring co... 2 [OK]\r\ntimhughes\/centos Centos with systemd installed and running 1 [OK]\r\ndarksheer\/centos Base Centos Image -- Updated hourly 1 [OK]\r\nsoftvisio\/centos Centos 1 [OK]\r\nlighthopper\/orientdb-centos A Dockerfile for creating an OrientDB imag... 1 [OK]\r\nyajo\/centos-epel CentOS with EPEL and fully updated 1 [OK]\r\ngrayzone\/centos auto build for centos. 0 [OK]\r\nustclug\/centos USTC centos 0 [OK]\r\njanuswel\/centos yum update-ed CentOS image 0 [OK]\r\ndmglab\/centos CentOS with some extras - This is for the ... 0 [OK]\r\njsmigel\/centos-epel Docker base image of CentOS w\/ EPEL installed 0 [OK]\r\ngrossws\/centos CentOS 6 and 7 base images with gosu and l... 0 [OK]\r\nlabengine\/centos Centos image base 0 [OK]\r\nlighthopper\/openjdk-centos A Dockerfile for creating an OpenJDK image... 0 [OK]\r\nblacklabelops\/centos CentOS Base Image! Built and Updates Daily! 0 [OK]\r\n<\/code><\/pre>\nsudo docker images<\/code><\/p>\nREPOSITORY TAG IMAGE ID CREATED SIZE\r\nfirefox-instance latest 8e61bff07fa0 3 weeks ago 354.6 MB\r\ncentos latest d0e7f81ca65c 4 weeks ago 196.6 MB\r\ndebian latest f50f9524513f 4 weeks ago 125.1 MB\r\napache\/ubuntu latest 196655130bc9 4 weeks ago 224.1 MB\r\napache-instance latest 7da78270c5f7 4 weeks ago 224.1 MB\r\napache-instance ubuntu 7da78270c5f7 4 weeks ago 224.1 MB\r\nhitjethva\/apache-instance ubuntu 7da78270c5f7 4 weeks ago 224.1 MB\r\n<\/code><\/pre>\nsudo docker<\/code><\/p>\nCommands:\r\n``` language-bash\r\n attach Attach to a running container\r\n build Build an image from a Dockerfile\r\n commit Create a new image from a container's changes\r\n cp Copy files\/folders between a container and the local filesystem\r\n create Create a new container\r\n diff Inspect changes on a container's filesystem\r\n events Get real time events from the server\r\n exec Run a command in a running container\r\n export Export a container's filesystem as a tar archive\r\n history Show the history of an image\r\n images List images\r\n import Import the contents from a tarball to create a filesystem image\r\n info Display system-wide information\r\n inspect Return low-level information on a container or image\r\n kill Kill a running container\r\n load Load an image from a tar archive or STDIN\r\n login Register or log in to a Docker registry\r\n logout Log out from a Docker registry\r\n logs Fetch the logs of a container\r\n network Manage Docker networks\r\n pause Pause all processes within a container\r\n port List port mappings or a specific mapping for the CONTAINER\r\n ps List containers\r\n pull Pull an image or a repository from a registry\r\n push Push an image or a repository to a registry\r\n rename Rename a container\r\n restart Restart a container\r\n rm Remove one or more containers\r\n rmi Remove one or more images\r\n run Run a command in a new container\r\n save Save an image(s) to a tar archive\r\n search Search the Docker Hub for images\r\n start Start one or more stopped containers\r\n stats Display a live stream of container(s) resource usage statistics\r\n stop Stop a running container\r\n tag Tag an image into a repository\r\n top Display the running processes of a container\r\n unpause Unpause all processes within a container\r\n update Update resources of one or more containers\r\n version Show the Docker version information\r\n volume Manage Docker volumes\r\n wait Block until a container stops, then print its exit code\r\n<\/code><\/pre>\n\r\nTo check system-wide information on docker, run:<\/code><\/pre>\n<\/code><\/pre>\nYou should see the following output:
\n<\/code><\/p>\n\r\nYou can use the following command to list all running containers:<\/code><\/pre>\n<\/code><\/pre>\nYou can see the running container in following image:
\n<\/code><\/p>\nsudo docker ps -a<\/code><\/p>\nsudo docker run \"container ID\"<\/code><\/p>\nsudo docker stop \"container ID\"<\/code><\/p>\nsudo docker ps<\/code> command.<\/p>\nsudo docker commit \"container ID\" image_name<\/code><\/p>\nsudo docker attach \"container ID\"<\/code><\/p>\nsudo docker stop $(docker ps -a -q)<\/code><\/p>\nsudo docker rm $(docker ps -a -q)<\/code><\/p>\nsudo docker rmi $(docker images -q -a)<\/code><\/p>\n