Blue Green Deployments

The master branch is the blue deployment, the branch you create will be the green deployment.

Launch the terminal in the OpenShift Console sandbox. It will use the default project created during the setup of your sandbox. After launching the terminal, follow the steps given below. Alternatively, you can do the same using the console interface. Refer to this tutorial.

Blue app from master

oc new-app https://github.com/{username}/blue-green-openshift#master --name=blue --strategy=source

Expose bluegreen service (using blue)

oc expose service blue --name=bluegreen

Green app deploy

oc new-app https://github.com/{username}/blue-green-openshift#green --name=green

Switch services to green

oc get route/bluegreen -o yaml | sed -e 's/name: blue$/name: green/' | oc replace -f -

Breakdown of the above command:

1. oc get route/bluegreen -o yaml : Returns the route configuration in YAML format
2. sed -e 's/name: blue$/name: green/' : The sed command replaces name: blue with name: green in the output above.
3. oc replace -f - : Replaces the route with the new config from stdin (first command).

Switch services back to blue

oc get route/bluegreen -o yaml | sed -e 's/name: green$/name: blue/' | oc replace -f -