Deploying a new version of a microservice in Kubernetes without downtime can be achieved by following these strategies:
Rolling Updates: This is the default strategy when you update a Deployment. Kubernetes incrementally updates Pods instances with new ones. If something goes wrong, you can roll back to the previous version.
Blue/Green Deployment: This involves running two environments: Blue is the live/production environment, and Green is the clone of the live environment. The new version of the microservice is deployed in the Green environment. After testing, the traffic is switched from Blue to Green, ensuring zero-downtime deployment.
Canary Deployment: In this strategy, you deploy the new version of the microservice (canary) along with the stable version. Initially, a small percentage of the traffic is sent to the canary. If it performs as expected, gradually more traffic is routed to the canary. If something goes wrong, you can route all traffic back to the stable version.
Shadow Deployment: This is similar to the Canary deployment, but the difference is that the same traffic is sent to both versions of the microservice (new and old), and only the results from the old service are used. This strategy is used when you want to test the new service with production traffic without affecting users.
Remember, all these strategies require a well-configured service mesh or ingress controller to control the request routing. Also, a good observability setup is crucial to monitor the performance of the new version and to make informed decisions.
Please note that the choice of strategy depends on the specific use case and the risk tolerance of the organization. It’s always recommended to have a rollback strategy in case things don’t go as planned.