What is a Sidecar Proxy?

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A Sidecar Proxy is a separate container that runs alongside an application container in a Kubernetes pod – a helper application of sorts. Typically, the sidecar is responsible for offloading functions required by all apps within a Service Mesh – SSL/mTLS, traffic routing, high availability, and so on – from the apps themselves. Sidecars are sometimes used to aggregate and format log messages from multiple app instances into a single file.

As data‑plane components, sidecars are typically managed by some type of control plane within the service mesh. While the sidecar routes application traffic and provides other data‑plane services, the control plane injects sidecars into a pod when necessary and performs administrative tasks, for example renewing mTLS certificates and pushing them to the appropriate sidecars as needed.

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[JaredHoush]

Thank you, John. Nice, concise explanation. It's an interesting pattern. It seems mildly inefficient in terms of container sprawl, though. I wonder if in the future container orchestration systems or the appropriate parts thereof could allow you to consolidate the sidecars. I'm torn, though. There's a lot good about this approach.

EDIT: Nevermind. I guess if you have to have the sidecar proxies for your mesh my concern is moot.

[shashvatpandey]

Hey, I want to make a sidecar container that will read all the traffic from the main container in order to maintain an automated API inventory, how do I suggest I move forward with this?