Zero Downtime Deployments

technical kubernetes deployment iaas paas

And Example of Zero Downtime Deployment


Kubernetes based platforms like OpenShift support zero downtime deployments using advanced deployment strategies like:

  1. Blue-Green Deployment
  2. A/B Deployment
  3. Proxy shard / Traffic Splitter

Most of these patterns require that your application supports [N-1 Compatibility]1

An Example

Rolling deployment

Step 1. Login using CLI

oc login [api-url] --token=[token]

Step 2. Download the example from Docker hub

docker pull openshift/deployment-example

Step 3. Create a new project

oc new-project rolling
# Ensure we are using the created project
oc project rolling

Step 4. Create an application based on the example image downloaded

oc new-app openshift/deployment-example

Step 5. Expose the service to the external traffic

oc new-app openshift/deployment-example

Step 6. Get external endpoint for the service

oc get routes

The external endpoint should be identified by HOST/PORT for deployment-example

Step 7. Scale the deployment to 3 replicas

oc scale dc/deployment-example --replicas=3

Step 8. Create an application with openshift/deployment-example:v2 image

This is a workaround so that openshift/deploymenteample:v2 image is available in the project

Step 9. Trigger rolling deployment by changing target image via tag

oc tag deployment-example-2:v2 deployment-example:latest

  1. Since many applications depend on persistent data, you will need to have an application that supports N-1 compatibility, which means you share data and implement live migration between your database, store, or disk by creating two copies of your data layer.