What is a sidekick container?

Question

When creating a new service, one can add "sidekick containers" to it. What is a sidekick container? And how does it differ from a "normal" service container?

Answer 1

TLDR: Sidekicks are normal services with the exception, that dns resolving between "main" service and sidekicks is automatically enabled, and that the bundle of containers is scaled equally and deployed on the same host machines.

According to Rancher v1.3 documentation:

Rancher supports the colocation, scheduling, and lock step scaling of a set of services by allowing users to group these services by using the notion of sidekicks

Furthermore,

When defining a sidekick to a service, you do not need to link the services as sidekicks are automatically