$Sidecar

A sidecar is a separate process or container that runs alongside an application instance. It handles tasks such as proxying, logging, managing configuration or secrets, and collecting telemetry.

Aug 20, 2026

Pros

• It separates supporting tasks from the main application code and works regardless of which programming language you use.
• The helper runs in the same environment and follows the same lifecycle as the application instance.
• You can set up or update shared features independently, without changing the main application.

Drawbacks

• Each workload replica uses extra CPU and memory.
• You need to coordinate startup, health checks, and version compatibility between the application and the sidecar.
• If the sidecar fails or is set up wrong, it might block access to an application that is otherwise working fine.