Blue-Green Deployments
With modern and mature DevOps, we all want smooth, sleek and painless automated deployments with zero-downtime. Sitecore deployments are no exception. Have you embraced zero-downtime deployments? This is not a new topic. If you look around Sitecore community, you see an odd question popping here and there regarding this topic.
The journey towards achieving zero-downtime deployments for any application in fact starts with your code base. So, in this series of blog posts, we will refresh ourselves on concepts like “Code Freeze” and the CI/CD process before deep diving into implementing Sitecore zero-downtime deployments.
- Sitecore Zero-downtime deployments – Part 1 (Do we need code or content freeze?)
- Sitecore Zero-downtime deployments – Part 2 (Sitecore Container CI/CD process)
- Sitecore Zero-downtime deployments – Part 3 (this post)
- Sitecore Zero-downtime deployments – Part 4 (Sitecore PaaS/AKS Zero-downtime deployments)
Blue-Green deployments architecture
In software engineering, blue-green deployment is a method of installing changes to a web, app, or database server by swapping alternating production and staging servers
Wikipedia
Key Concepts
In its purest form, true BLUE/GREEN deployments means that we need two separate but identical environments, one is live (BLUE) and the other is on stand-by (GREEN). When you have new version of your application, you deploy to the staging environment (GREEN) , test it without affecting BLUE. When you are happy with this new version, you can then swap it to be LIVE instance.
However, in practice, it doesn’t always make sense to run a copy of every resource. Furthermore, this may introduce some complexity to the process.
This is why we now have some shared resources as you can see in the infographic above, while others belong to BLUE or GREEN environment.
As part of this architecture, we need some way of switching or routing incoming traffic between the two environments.
Blue-Green deployment strategy effectively enables us to achieve zero down time deployments. This is because your users will not notice any downtime during deployments.
CI/CD process for Blue-Green deployments
On the top part of the infographic above, – BLUE is currently production environment and our users accessing this environment. When we have, a new version of our application, it is deployed to GREEN environment, without affecting our users.
On the bottom part of the infographic above, – now GREEN is the production environment and our users are accessing this environment. This leaves the BLUE environment available for us to deploy the next version of our application
We deploy to BLUE and GREEN in turns, this achieving zero downtime deployments. The process repeats in each deployment cycle.
Some benefits of Blue-Green strategy
If you haven’t already adopted the cloud for your Sitecore workloads – be it PaaS or Containers, then perhaps you need to start thinking about this seriously as there are benefits you will get.
“Blue-green deployments made easier with the cloud.”
fact
The cloud provides tooling you need to:
- Automate your provisioning and tearing down of environments
- Automate starting or stopping of services
- Kubernetes simplifies container orchestration for us, the Azure Kubernetes Service (AKS) provide a Control Plane for free
- The flexibility and cost reductions the cloud offers makes blue-green deployments within everyone’s reach at this time and age, please embrace them.
Next steps
Hopefully, these blog post help you understand key concepts about BLUE-GREEN deployments.
In the next blog post in this series, we will look at implementing Sitecore Zero Downtime deployments.
