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Blue/Green Deployment Strategy

You've probably heard or seen the word blue/green if you're into cloud computing. Someone has probably told you that the blue/green deployment technique involves releasing bug-free software while minimizing application downtime and offering an immediate means of rolling back changes. This is very true.

This intricate Deployment strategy has left even the global pros in the cloud computing industry, scratch the top of their head. So if you're here, you're here for the right reason because, in this article, I'm going to tell you:

  • What blue/green deployments are?

  • How does blue/green deployment work?

  • How it can be an essential strategy for you?

  • When can you implement this technique?

  • Challenges you are likely to face.

  • Blue/Green Deployment and Kubernetes.

Let's get started.

What is Blue/Green Deployment?

A deployment approach known as a "blue/green deployment" involves establishing two distinct yet similar environments. The new application version runs in the environment (green), while the existing one runs in the environment (blue).

By streamlining the rollback procedure if a deployment fails, a blue/green deployment strategy promotes application availability and lowers deployment risk. After the green environment has undergone testing, the blue environment is discarded, and actual application traffic is switched to the green environment.

Confused? I'll break it down with this corresponding fine example.

You are developing a website that offers movie tickets as a DevOps engineer. The good news is that microservices that manage authentication services, movie updates, new trailer releases, and other tasks now support your website's backend. But you want to roll out an upgrade that includes a timer and exclusive booking for midnight openings, and you don't want to wait until 3 in the morning when the fewest users are online.

Additionally, you don't want consumers to encounter delays and disruptions when doing financial transactions. However, how can you guarantee unbroken uptime and steady transactions while having a good night's sleep? Deploying blue/green is the solution.

Therefore in more straightforward, relatable, and fun terms, Blue/green deployment is a DevOps release management approach that lowers the risks associated with code distribution and downtime. To conduct testing and offer dependable zero downtime software upgrades, this approach uses two identical production environments (blue and green).

To achieve immutable infrastructure, you must redeploy your application once any modifications have been made to your application once it has been deployed.

That must be easier to grasp. Let's go on to the next challenging yet enjoyable section of this article.

How does Blue/Green Deployment work

Blue/Green deployment architecture

Two distinct but similar settings are the foundation for blue/green deployments. The environment in this context refers to whatever you need to run your code, including operating systems, servers, virtual machines, containers, and virtual machines.

The environments might occasionally be two physically separate computers, two virtual machines using the same hardware, or even two distinct containers running on the same device. The new or test environment is referred to as green, whereas the old or live environment is referred to as blue.

It's crucial to remember that when testing is finished, both blue and green are active in production. In the construction of a green environment, traffic progressively switches from blue to green.

After deployment, blue becomes a test environment for deploying new code, and green becomes a live environment. Blue can then be ready to act as a disaster recovery mechanism or in the event of rollbacks.

Let's take a closer look at this now. Think of the environments as being blue for production that is currently underway and green for staging. Since blue is now in use, all production traffic is routed via it, and green is free to execute a comprehensive test suite.

The necessity for a system to switch traffic between blue and green must always be kept in mind. Depending on the situation, this mechanism can be a web server, load balancer, or router.

Production traffic may progressively be switched from blue to green once we are confident that everything is operating well in the green. Our deployment will be complete after all traffic changes to the green light.

Blue/green deployments may be more accessible and widely available thanks to the cloud. But how?

With the use of the cloud, we can hide away the infrastructure and launch instances as needed. Blue-green deployments have become much more cost-effective because of the scalability and cost-effectiveness of cloud computing because we no longer need to keep two distinct copies of everything. The idea applies to the cloud as well.

CI/CD technologies may be used to establish a similar new environment whenever we need to launch a new version. Because the cloud enables us to spin up trash environments as required, we can also divert production traffic to green. We can preserve the blue environment as a backup or crisis recovery system if we need to roll back, or we may remove it cost-effectively. Simply swapping or diverting production traffic to the blue environment will enable us to achieve this instantly.

When can you implement the Blue/Green Technique

Quick Releases

A blue/green deployment is an excellent technique for product owners working in a CI/CD system to put software into production swiftly. DevOps teams don't need to plan weekend or after-hours releases since they may release software anytime. Since there is no accompanying downtime, these deployments have no adverse effects on users.

Updates are also made simpler for DevOps teams by blue/green deployments. Updates shouldn't be hurried during deployments because doing so might result in mistakes and unneeded stress.

Easy Rollbacks

If something goes wrong, blue/green deployments provide you with a simple option to revert to a secure, functional version. By doing this, the dangers of testing new ideas in a working context are diminished. With a few straightforward routing adjustments, teams can quickly solve problems and return to a reliable production environment.

When rolling back, there is a chance that ongoing transactions will be impacted if the application is stateful. Making the application read-only throughout the transition is one strategy to address this problem. Another method is to implement a rolling change using a load balancer or service mesh, waiting for each transaction to finish before rerouting the user to the blue variant.

Production Testing

Despite best efforts, there will almost always be variations between the staging and production settings. This may result in exceptions and defects that aren't found until the latest version is released to the public. DevOps teams may try out new code in a natural production environment using a blue/green deployment to look for last-minute bugs and assess performance. After that, traffic may be effortlessly transferred to the new variant.

A/B Evaluation

A/B evaluation is an additional possible use for blue/green deployments. In this use scenario, a new code version is placed into the blue environment, and a portion of user traffic — usually more than 40% — is diverted to the blue version in place of the original green version. After that, you may evaluate the impact of the new variant by keeping an eye on critical metrics for both environments' performance.

Challenges of Blue/Green Deployment

Blue/green deployments are very quite advantageous. However, there are a few things you need to be aware of. They are:

Setup difficulty and duration

A blue/green deployment requires a complicated, dangerous setup that may require many tries to get right. You may utilize specialized tools with built-in blue/green deployment features in a Kubernetes environment.

Cold initiation

When moving to a new environment, users may encounter performance problems. The cut-off point between two environments may also contain additional unforeseen issues. Running warm-up exercises and stress tests can help to ease this.


The production environment must be doubled for a blue/green deployment. Running on-premises necessitates the purchase of additional hardware. It might result in twice the infrastructure costs in the cloud.

Migration of schema

Migration of databases is a challenging process. Database schema modifications are generally not supported by blue/green deployments. Keeping the data synchronized might be challenging even when the schema remains unchanged. Replication and making the database read-only throughout the changeover are common tactics.

User interaction

Interactions may fail when traffic changes from blue to green or vice versa. One solution is to display an error and request that the user tries their transaction again. However, this results in a bad user experience. Serving all transactions in tandem with both environments is a superior solution. After the deployment, duplicate data must be cleaned up.

Common services

If indeed, the application relies on a third-party database, another legacy service, or any other external service, then the information from those services may leak across the blue and green environments. Testing may become unstable, and deployment may be hampered if one environment indirectly impacts the other.

Blue/Green Deployment & Kubernetes

The ecosystem of choice for development, testing, and production deployments for many development teams is Kubernetes. By automating blue/green deployments, Kubernetes helps simplify the process of deploying applications.

Blue/green deployments aren't offered by default with Kubernetes, though. For "rolling updates," it provides the Deployment object. This allows for the progressive replacement of pods with a new version of an application, allowing for updates to be made to an application with no downtime.

Although it does not offer all of the advantages of blue/green deployment, this is close to it. If there is a problem with the new version, it may be challenging to roll it back in a rolling deployment. Additionally, it takes time to roll out the application; contrast, a blue/green pattern allows for a seamless transition.

End Note

Since Kubernetes, an open-source platform that automates Linux container operations, all the components of the blue-green deployment process, such as microservices, cloud-native apps, continuous integration, containers, continuous, SRE, continuous deployment, continuous delivery, and DevOps, naturally fit together with Kubernetes.

Blue-Green deployment with CNO

CNO offers the Blue/Green Deployment Strategy, you can monitor and manage your deployment either through the terminal or the User Interface, increasing your ease of Kubernetes adoption. Contact us for a free demonstration.

Last update: 2022-11-15