Managing Docker Images – Openshift Tutorial

Managing Docker Images – Openshift Tutorial

Objectives:

  • Install git and Download a Demo Application
  • Create/Modify Docker file for the Application
  • Build the Image from Downloaded Application using Docker File
  • Run the Container from Local Image
  • Tag and Push the Image to Docker Hub
  • Remove the Image.

Pre-requisite

  • Local CentOS 7 VM with root access.
  • Docker-Engine pre-installed.

Sequence 1. Working with Containerized Application

  1. Pull sample app and clone an application from Github for testing

# git clone https://github.com/dockersamples/node-bulletin-board

# cd node-bulletin-board/bulletin-board-app

  1. Check the contents of Dockerfile in the bulletin board application.

# ls

# cat Dockerfile

  1. Run the following command to build your bulletin board image:

# docker build –tag bulletinboard:1.0 .

You’ll see Docker step through each instruction in your Dockerfile, building up your image as it goes.

  1. Run your image as a container by executing following command:

# docker run –publish 8000:8080 –detach –name bb bulletinboard:1.0

  1. Visit your application in a browser at http://localhost:8000 or from your host machine visit http://10.10.0.200:8000. You should see your bulletin board as given in the screen shot.

  1. Share Your Image on Docker Hub. Use the docker command in your terminal to login

# docker login

  1. Check the image ID and create an additional tag for your image which should be pushed to Docker Hub.:

# docker image list

REPOSITORY      TAG                 IMAGE ID            CREATED             SIZE

bulletinboard   1.0                 bb538a7697d8        57 minutes ago      177 MB

docker.io/node  current-slim        3aaf4acbaad7        13 hours ago        159 MB

# docker tag bb538a7697d8 sangwan70/openshift:mybb

 

I’m using my Docker Hub username sangwan70 and I’m telling Docker to create a new tag with the name sangwan70/openshift:mybb

  1. Now use the docker push command to actually push the image to Docker Hub and make it available publicly, so that it can be used anywhere:

# docker push sangwan70/openshift:mybb

The output on the command line should look like you can see in the following screenshot:

    1. Verify your Image on Docker Hub. Open the Tags tab to check the image pushed
    2. Clean up. Once you’re satisfied that your bulletin board container works correctly, you can delete it:

# docker rm –force bb

# docker ps -a

# docker images

# docker rmi -f $(docker images -a -q)

# yum clean all

# docker system prune

Watch the Lecture

 

February 5, 2021
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