Understanding Blue Green Deployment

What this blue-green all about?

This is a way of switching traffic from one deployment to another one. That means say you have a new version of software to roll out, which has been successfully tested in staging environment. Now you want that to go-live, so here in kubernetes you have this magic word blue-green deployment.

Definition: "A blue green deployment uses the service label selector to switch all traffic from one deployment to another."

If above stated definition is cryptic, than lets see an image view to understand it;

Here if you notice, we have app:hello version:1.0.0 is currently deployed. Now let's say we have a new version i.e. 2.0.0 of hello app;

First test you new deployment, i.e. version 2.0.0. Once you have verified it, it's time to switch live traffic to version 2.0.0 deployment.

Now let's get back to the definition, we discussed previously. It says use service label selector to switch traffic. Awesome we are on track understanding traffic switch.

Here we have successfully switched to new version 2.0.0 with help of "selectors & labels". That means if we want to get all this done, the mantra is to understand "labels & selectors".

Got it, now you must be asking where the heck is this labels & selectors discussion. Need not to worry we will soon see a video tutorial because that needs much attention.

Very well, we have made a basic understanding of blue-green deployment.

Enjoy :-)