Canary release vs smoke test: Choosing a deployment strategy

Canary release

Canary releases are a deployment strategy where a new version of an application is gradually rolled out to a small subset of users before being deployed to the entire user base. This approach allows teams to test new features in a production environment with real users while minimizing risk. If issues arise during the canary phase, the release can be quickly rolled back, affecting only the small percentage of users exposed to the new version.

The name “canary” references the historical practice of coal miners who brought canaries into mines to detect toxic gases. Similarly, canary releases serve as early warning systems for potential problems in software deployments. By monitoring the performance of the canary release closely, teams can gather real-world data about how the new version behaves before committing to a full deployment.

Smoke test

Smoke testing is a preliminary testing technique that verifies the critical functionalities of a software application to ensure they work as expected before proceeding with more extensive testing. In the context of deployment, smoke tests are run immediately after deploying a new version to confirm that the fundamental aspects of the application are functioning correctly. These tests focus on the core features and are designed to be quick and non-exhaustive.

The term “smoke test” originates from hardware testing, where the first test was simply to turn on the device and see if smoke appeared (indicating a serious problem). In software deployment, smoke tests serve a similar purpose—to quickly identify catastrophic failures that would render the application unusable. This allows teams to catch major issues early in the deployment process, potentially saving time and resources by preventing deeper testing of a fundamentally broken build.

Comparison: Canary release vs. smoke test

Timing

• Canary Release: Occurs during the actual production deployment, with real users experiencing the new version.

• Smoke Test: Typically runs immediately after deployment but before exposing the changes to users.

Duration

• Canary Release: Extended observation period, often lasting hours or days.

• Smoke Test: Brief verification process, usually completed in minutes.

Audience

• Canary Release: Real users, often segmented by demographics, usage patterns, or randomly selected.

• Smoke Test: Typically performed by QA teams or automated systems, not involving actual users.

Scope

• Canary Release: Full system functionality is tested under real-world conditions.

• Smoke Test: Focuses on critical paths and core functionality only.

Risk management

• Canary Release: Limits exposure of potential issues by affecting only a subset of users.

• Smoke Test: Identifies major issues before users are exposed to them.

Rollback strategy

• Canary Release: Gradual approach allows for easy rollback affecting only a small percentage of users.

• Smoke Test: Failed tests typically prevent deployment from proceeding to production.

Feature flags with deployment strategies

Feature flags integrate seamlessly with canary releases by providing fine-grained control over which users see new features during the gradual rollout. When implementing a canary release, teams can use feature flags to enable new functionality for specific user segments while keeping it disabled for others. This approach adds an additional layer of safety, as teams can instantly disable problematic features without rolling back the entire deployment. Feature flags also allow for more sophisticated canary testing, such as enabling different features for different user cohorts to gather comparative performance data.

With smoke testing, feature flags serve a different but complementary purpose. Before running smoke tests, teams can ensure that all test-critical features are enabled in the testing environment while keeping them disabled in production. This allows the smoke tests to verify new functionality without affecting real users. If smoke tests pass, teams can then selectively enable features in production according to their release schedule. This separation of deployment from feature activation provides greater flexibility and reduces the risk associated with deploying new code.

Canary releases and smoke tests represent two distinct approaches to software deployment. A canary release gradually exposes a new feature or update to a small percentage of users before a full rollout, allowing developers to monitor performance and gather feedback in a real production environment with minimal risk. This method excels at catching issues that might only appear under genuine user conditions and provides the opportunity to roll back changes if problems emerge without affecting the entire user base. However, canary releases require sophisticated infrastructure to manage traffic splitting and monitoring, can be time-consuming to implement properly, and may create inconsistent user experiences during the partial deployment phase.

Smoke tests, by contrast, involve running a preliminary set of tests on a new build to verify that the most critical functions work before proceeding with more thorough testing or deployment. This approach efficiently identifies major failures early in the process, saving resources that might otherwise be wasted on more comprehensive testing of fundamentally broken builds. Smoke tests are typically quicker to execute and require less complex infrastructure than canary releases. Choose smoke testing when you need rapid validation of basic functionality before proceeding with deployment or further testing. Opt for canary releases when you need to evaluate how changes perform under real user conditions, especially for complex features where user behavior and system load are difficult to simulate in testing environments, and when you can accept a slightly longer deployment timeline in exchange for reduced risk.

Frequently asked questions

What are the insurance providers that offer Canary release insurance?

The article doesn’t mention any insurance providers that offer Canary release insurance. Canary releases refer to a software deployment strategy where new versions are gradually rolled out to a small subset of users before full deployment, not an insurance product.

What is a Canary Release?

A canary release is a deployment strategy where a new version of an application is gradually rolled out to a small subset of users before being deployed to the entire user base. This approach allows teams to test new features in a production environment with real users while minimizing risk. The name “canary” references coal miners who brought canaries into mines to detect toxic gases – similarly, these releases serve as early warning systems for potential problems in software deployments.

How does a Canary Release differ from a Smoke Test?

Canary releases occur during actual production deployment with real users experiencing the new version over an extended period (hours or days). They test full system functionality under real-world conditions. Smoke tests, however, run immediately after deployment but before exposing changes to users, are completed in minutes, are performed by QA teams or automated systems, and focus only on critical paths and core functionality.

What is the role of Feature Flags in Canary Releases?

Feature flags integrate with canary releases by providing fine-grained control over which users see new features during gradual rollout. Teams can use feature flags to enable new functionality for specific user segments while keeping it disabled for others. This adds an additional safety layer, as teams can instantly disable problematic features without rolling back the entire deployment, and allows for more sophisticated testing across different user cohorts.