In this article, will discuss about canary vs blue-green deployment, which should help team to choose the best process for their product release.
What is Canary Deployment?
In software engineering, canary deployment is the practice of making staged releases. We roll out a software update to a small part of the users first, so they may test it and provide feedback. Once the change is accepted, the update is rolled out to the rest of the users.
This technique helps to reduce the risk of updating software or introducing new changes in the production environment by slowly rolling out the change to a small subset of users before making the software functional for everyone. Also, this process offers no-downtime upgrade and simple rollbacks.
Pros
Canary deployments provide the following benefits to businesses.
- Allows enterprises to test in production with real users and use cases.
- Enables comparison of different service versions side by side.
- Cheaper than blue-green deployments because it does not require two different production environments.
- DevOps team can rapidly and safely trigger a rollback to a previous version of an application.
Cons
- Scripting a canary release can be complex as manual verification or testing can sometimes become time-consuming.
- Monitoring and instrumentation for testing in production may involve exhaustive research and additional skills & knowledge.
What are Blue/Green Deployments?
Blue/green deployment is a deployment technique to release new code into the production environment. Blue/green deployments make use of two identical production environments — one of these is active and the other environment is set to idle. New updates are pushed to the active environment where it is monitored for bugs while the idle environment serves as a backup where traffic can be routed in case an error occurs.
Pros
- Simple, fast, easy to understand and implement.
- Rollback is straightforward as teams need to simply flip traffic back to the old environment in case any issue arises.
- Blue-green deployments are not as risky and vulnerable to losses as compared to other deployment strategies.
Cons
- Cost is the major drawback to blue-green deployments. Replicating a production environment can be complex and expensive, especially when teams have to work with microservices.
- Quality assurance and user acceptance testing may not be enough to identify all of the anomalies or regressions.
- An outage or issue can pose a large-scale business impact before a rollback is triggered.
Blue/Green vs Canary
So which method, blue-green or canary, is the best way to deploy with zero downtime?
Both are effective strategies, and both require a fairly similar architecture, but there are different features.
If you have the resource/environment capacity for two complete application hosting, and your application rarely changes in a way that is not backwards compatible, blue-green offers the most secondary benefits with minimal application changes. It enables a zero-downtime environment that you can also leverage when performance issues occur, or during a disaster recovery situation.
In case, you are limited in how many extra resources you can provision, or your application is modular and configuration-driven, you can use the canary deployment option instead. While you lack an extra environment to use for other concerns, you minimize the amount spent operating and maintaining your environment. Canary deployment also provides an easier way to enable and disable features at any point or based on any set of criteria.
Both methods, require some pre-planning and thought about the architecture of your applications and environments.
Summary
The real test comes when people start using our application. Canary deployments allow us to do controlled trials with real users. When we combine this strategy with a fast CI/CD workflow, we get a productive, feature-rich release cycle.
This is vest topic to understand lot of factors before we decide, in coming posts will see about the canary and blue/green deployment in details.