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Blue-Green Deployments

The purpose of this short lab is to demonstrate how simple it is to implement Blue-Green Deployments in OpenShift v3.

"Blue-green deployment is a release strategy that can be utilized by developers for deploying software in a production environment. Blue can be one particular production environment whereas green can define an identical production environment. Under blue-green deployment strategy, software developers are able to minimize downtime and reduce risk." 1*

In this Lab, we will be:

  • Deploying two versions of the same application. The first version will display a blue rectangle.

  • Create a FQDN that can be used to expose the applications.

  • We will first expose the first application.

  • We will also create another version of this application in the same project that displays a green rectangle.

  • We will then switch the FQDN to from the first application (blue) to the second application (green).

image

Part I

Step 1: Create a new project

Important
 Please replace userxx with the username assigned to you in the commands below. IMPORTANT: Please replace userxx with your username
image

  • Enter bluegreen-userxx as project name (all lower case)

image

  • Click Create

Step 2: List existing image builder or image streams

  • Click Add to Project -→ select Browse Catalog

  • Click PHP

  • Click drop down from the version under PHP and get the list of image stream

image

Step 3: Create an application

We will be using a sample application that displays a blue or green rectangle. The sample app can be browsed at https://github.com/RedHatWorkshops/bluegreen

We will be using an env var in order to change the color of the box; but in practice you would use a different branch for each version of the code. (E.g. v1 branch and v2 branch)

  • Click Add to Project -→ select Browse Catalog

  • Click PHP

image
image

  • Click advanced options link below to expand the options area

  • Scroll down to Deployment Configuration session

  • Add COLOR as key and blue as value

image

  • Scroll down and click Create

Step 4: Monitor the application build

  • Click Builds -→ Builds

  • Click onto #1

  • Click Logs tab

    Once the build finishes you should see something similar to:
    ...
Pushing image docker-registry.default.svc:5000/guide/blue:latest ...
Pushed 0/6 layers, 2% complete
Pushed 1/6 layers, 27% complete
Pushed 2/6 layers, 40% complete
Pushed 3/6 layers, 53% complete
Pushed 4/6 layers, 73% complete
Pushed 4/6 layers, 92% complete
Pushed 5/6 layers, 97% complete
Pushed 6/6 layers, 100% complete
Push successful
...

Step 5: Check application deployment status

  • Click Applications -→ Pods

  • Pods blue shows Running Status

Notice that the build pod has Completed and you now have a single instance of the application running under one single pod.

This application displays a blue square.

Step 6: List the service

  • Click Applications -→ Services to view all services

Step 8: Test the application

  • Click Overview

  • Click route link on the top right on the screen

At this point you have deployed an application that displays for illustration purposes a blue rectangle for version 1.

Part II

In this part, we will:

  • Deploy a new version of this application (Same one as before with a very small change)

  • Point the previously created FQDN (route) to the new service that will be created as part of the new application creation process.

image

Step 1: Create new version of the application

Create a new application the same way as you did above in Part I. Make sure to name the application as 'green' this time.

  • Click Add to Project -→ select Browse Catalog

  • Click PHP

  • Click Select in the PHP option

  • Enter name as green

  • Enter Git Repository URL as https://github.com/RedHatWorkshops/bluegreen

  • Click advanced options link below to expand the options area

  • Scroll down to Deployment Configuration session

  • Add COLOR as key and green as value

  • Scroll down and click Create

    • Wait until the application is built and deployed. You should now see two services on Overview

Step 2 Edit service Edit the previously created route and change the service name (from blue to green), all the way at the bottom to the new service that was just created. You are essentially still using the FQDN you had previously created. However, that route will now point to a different (green) service.

  • Click Applications -→ Routes

  • Click blue

  • Click Actions -→ Edit

  • Select green under Service

  • Click Save

Step 2: Test the application

  • Click onto the Route URL

    • You should now see the new version of the recently deployed application with a green rectangle.

Summary

  • Blue-Green deployments can be easily accomplished in OpenShift v3.

  • We have shown multiple versions of an application; all running concurrently, each with a unique service.

  • All that is needed to expose any of the applications is to change the service being used by the route to publicly advertise the application.