Sidecar

1. The Pattern

Deploy a small helper process beside every service instance. It runs on the same machine and talks to the service over localhost. The helper does the networking work: TLS, retries, timeouts, metrics, and tracing. The service does only its own job.

The module turns inward here, to east-west traffic: the calls services make to each other. The first thing you see on the inside is a familiar problem.

Service-to-service calls need their own supporting work. They need mutual TLS, which is encryption where both sides prove their identity