Sidecar Pattern
Running a helper process alongside your main application container to handle a cross-cutting concern, independent of your app’s own code.
The sidecar pattern deploys a second, helper container in the same pod/host as your main application — handling concerns like traffic proxying, log shipping, or certificate rotation — so that logic doesn’t need to be built into every application’s own codebase in every language your org uses. A service mesh’s per-instance proxy is the most common real-world example of a sidecar.