The Benefits and Drawbacks of Different Upgrade Strategies

Deploying new application versions into production is a critical process that requires careful planning, testing, and execution. One of the most challenging aspects of this process is performing upgrades while ensuring that the application remains available and is functioning properly.

In this article, we will discuss the different strategies that can be used for performing upgrades while deploying new application versions into production, as well as the challenges that can arise when the database schema changes. Because most of the applications are not just code, but also the data which it operates on.

The Rolling Upgrade Strategy

The rolling upgrade strategy involves upgrading one server at a time, while the other servers continue to run the older version of the application. This approach allows a gradual and controlled upgrade process that minimizes downtime and risks.

However, this strategy can be more complicated to implement than other approaches and may also require additional testing to ensure that the new version of the application is compatible with the older one.

The Blue-Green Deployment Strategy

The blue-green deployment strategy means deploying the new version of the application on a completely separate set of servers, often referred to as the “green” environment. While the old version of the application continues to run on the existing “blue” environment.

Once the new version of the application is tested and verified, traffic is switched from the old environment to the new environment. This approach allows for a seamless and risk-free upgrade process, but it can be more expensive and may require additional infrastructure.

The Canary Release Strategy

The canary release strategy involves gradually releasing the new version of the application to a small subset of users, often referred to as the “canary” group, while the majority of users continue to use the older version of the application.

This technique ensures early detection of any issues with the new version of the application, while minimizing the impact of any problems on the user experience. However, it can be more complex to implement and may be in need of additional monitoring and testing.

The Immutable Infrastructure Strategy

The immutable infrastructure strategy is – creating a new set of servers, each with a clean and identical configuration, and deploying the new version of the application to these servers. This approach shows a highly reliable and repeatable upgrade process, but it can be more time-consuming and in some cases require additional infrastructure.

Regardless of the strategy chosen, upgrading an application in production can be complicated, especially when the database schema changes. A change to the database schema can impact the application's ability to function properly and can cause data loss or corruption.

To mitigate these risks, it is important to thoroughly test the new application version against the new database schema. Special migration tools are usually used to simplify the migration process between the different environments. And it is absolutely required to have a plan in place for migrating data from the old schema to the new schema.

In conclusion, performing upgrades while deploying new application versions into production is a complex process that requires careful planning, testing, and execution. The rolling upgrade, blue-green deployment, canary release, and immutable infrastructure strategies are all viable options for upgrading applications, and organizations should select the strategy that best meets their needs.