Blue-Green vs. Canary Deployments: Which Strategy Ensures Safer Releases?

Your deployment strategy can make or break your release cycle. Blue-green and canary deployments are two popular approaches for minimizing the risk. However, they are not interchangeable, and it is essential to understand the difference to select the right one. Or if you are stuck in canary vs blue-green deployment strategy, then this blog can help you make a decision too, so you can ensure safe deployment.

Let’s begin with canary deployment.

What Is Canary Deployment?

It is a strategy that focuses on gradually rolling out updates to a subset of users before full release. This allows deployment teams to incrementally deploy new features or updates, reducing the likelihood of widespread issues. Initially, only a small group of users (called canaries) is exposed to the changes. Allowing the team to find the minor bugs or performance issues within a limited scope, while protecting the broader user base. 

In short, the deployment can be rolled back quickly (if something goes wrong), and viewing the pictorial representation below can help you understand the concept more.

In case you have decided that canary is your next deployment strategy. Then you might have gained an idea about its pros, but you should also know about its cons too.

Pros 

• Rollback to previous versions is quick and reliable.
• Helps compare different service versions running side by side.
• Allows testing in production with real users and real-world scenarios.
• More cost-effective than blue-green deployment, as it eliminates the need for duplicate environments.

Cons

• Manual verification or testing may require extra effort.
• Testing canary in production may be risky and needs careful setup.
• Implementing canary can be a complex and time-consuming process.
• Setting up the necessary monitoring and instrumentation for testing might need additional research.

As mentioned above, in canary deployment, the new version of the app can run for a small portion of the traffic while most users still use the old version. Let us give you an example. 

Example: Canary Deployment in Kubernetes

This config runs a new version (v2) of the app for a small portion of traffic, while most users still use the old version.

apiVersion: apps/v1

kind: Deployment

metadata:

  name: myapp-canary

spec:

  replicas: 2

  selector:

    matchLabels:

      app: myapp

      version: canary

  template:

    metadata:

      labels:

        app: myapp

        version: canary

    spec:

      containers:

      - name: myapp

        image: myapp:v2

Now that you know about canary, as per the title of our blog, we will move on to blue-green deployment. However, it’s not the end for canary, as we will conduct a head-to-head comparison of both in the end.

What Is Blue-Green Deployment?

It is a strategy that utilizes two identical production environments, referred to as a blue-green deployment. The blue environment represents the live outgoing environment, while the green environment serves as the next version in readiness. Once the changes are fully tested, the traffic is switched from blue to green. This redirection of traffic reduces downtime, and any issues that arise can be easily addressed by reverting to the blue setup.

In short, it is a strategy that improves application availability, as well as its simplicity, by reverting to a previous state if problems arise. Let us provide you with a pictorial representation of how it works.

If you have left the canary and want to adopt blue-green as your next deployment strategy, then study the pros and cons to make the best decision.

Pros

• Simple, fast, and easy to implement
• Well understood in the engineering community and less risky.
• Straightforward rollback by switching traffic back to the old environment.

Cons

• Maintaining two production environments can be costly.
• Any problem or outage can have a large impact before rollback.
• Replicating the production environment can be difficult (especially with microservices).
• Switching all traffic at once can be risky (QA and user testing might not catch all issues).

As also discussed, in blue-green deployment, traffic switching is performed. Let us provide a practical example of switching using NGINX.

Example: Switching Traffic from Blue to Green (Using NGINX)

This example demonstrates how traffic is initially routed to the blue environment and then switched to green when ready.

# Step 1: All traffic goes to Blue environment

upstream myapp {

    server blue.myapp.com;

    # server green.myapp.com;  # Green is ready but inactive

}

# Step 2: Switch all traffic to Green environment

upstream myapp {

    # server blue.myapp.com;   # Blue is now inactive

    server green.myapp.com;     # Green is active

}

To further clarify the concept and help you make the best decision for the safe deployment of your solution, we are providing a head-to-head comparison of both.

Blue-Green Deployment vs. Canary Release: Which One to Choose?  

A head-to-head comparison of both canary release and blue-green deployment is given to help you understand the full difference: 

Selecting a deployment strategy is a significant decision, and choosing the wrong one can lead to user frustration due to the inaccessibility of the app or its features. This will also cost you money and time.

Pick the Right Deployment Strategy for Safer Deployment with Confidence 

Let us explain this in a simple manner so that you can become clear on canary deployment vs blue-green once and for all.

• If you want zero downtime and have a budget for duplicate environments, then the blue-green strategy is fine.
• If you want to test safely with real traffic and don’t want to waste resources on two full setups, then a canary deployment is the way to go. 

Or you can book a free 30-minute call with our experts to get guidance.

Frequently Asked Questions

Is blue-green deployment risky?

It is less risky as it minimizes the downtime by running two identical production environments, referred to as blue (production) and green (new version). By running two identical production environments, the traffic can be switched gradually.

Does the canary deployment strategy have downtime?

It is a zero-downtime strategy where new software is rolled out to a small subset of users before being fully released to the rest of the users.

When is it appropriate to use the canary deployment strategy?

You should use canary deployment when you want to test new features on a small group of users first to minimize the risk before rolling them out to the whole user base.

What is Kubernetes Blue-Green Deployment?

Blue-green deployment is an ideal way to maximize your app’s health running in Kubernetes. Furthermore, Kubernetes makes it easy to get started with blue-green deployments, making the platform work well in challenging environments.