A Canary Launch is a technique to reduce risk when releasing a new feature or product by incrementally rolling out changes to segments of users before releasing to everyone.

Also referred to as canary release, canary deployment, or partial rollouts.

Let’s look at an example:

• An e-commerce company wants to change their “Add to cart” button to say “Shopping cart”.
• They have an idea how this change will affect metrics like ‘add to cart’, ‘purchase event’, and ‘revenue’ but want to test to ensure the feature has the intended effect.
• The team ships the “Shopping cart” change to 5% of users in the US.
• After some time they increase to 10%, then 30%, 50%, etc, until the feature is either shipped to all users or abandoned.
• Starting with a small % of users eliminates detrimental risk, identifies bugs/breaks earlier, and builds confidence.

The term canary launch or canary release comes from the old practice of coal miners sending canary birds into mining tunnels as an alert for toxic gases. Tragically, the gas would kill the canary before miners and this would warn the miners to leave the tunnels.