Traffic split is a key concept that has recently gained popularity. It abstracts networking functions through a proxy without having to change the application. Traffic split allows dark launches of applications to select groups of users such as co-workers, friends, and family. Canary deployments (progressive traffic shift), A/B testing (HTTP header and cookie traffic routing), and blue/green deployments (traffic switch) are all examples of dark launches for testing applications in production environments by routing a percentage of the live traffic to selected groups of users without their knowledge. These capabilities do not exist out of the box in a traditional monolithic environment.

Linkerd works with Flagger (https://flagger.app), which is an open source Kubernetes operator for canary deployment that uses Linkerd. Flagger can be used with Linkerd to provide canary and blue-green deployments.

Linkerd recently announced the service mesh interface specification for traffic split.