Sidecar

The Pattern

Deploy a small helper process alongside every service instance: same machine, joined at localhost: and let it handle the networking chores: TLS, retries, timeouts, metrics, tracing: while the service does only its job. The motorcycle sidecar: along for every ride, carrying the gear, driven separately.

The module turns east-west here, and the first thing visible on the inside is a familiar disease. Internal service-to-service calls need their own chores: encrypting traffic between services (mutual TLS), timeouts, [retries](