Layer 3 · Go deeper · 8 min
Go deeper
Size it, build it, then make the calls an interviewer will push you on.
Back of the envelope
Size it up
Tap through each step of the arithmetic.
How much do sidecars add to a four-call checkout?
One tap, three hops, a slow bank API. How many attempts?
What does ambient mode save on the same platform?
Build-up · 5 steps
Follow one call through the mesh
Orders calls payments in Istio’s sidecar mode. Watch what the data plane and the control plane each add, one piece at a time.
Step 1 of 5
The app calls payments:8080
Orders makes a plain call to http://payments:8080, exactly as it would with no mesh. That is the point. Retries, mTLS and metrics are about to arrive without touching this code.
4 interview moments
You’re the candidate
The interviewer pushes on the hard parts. Pick an approach and see how it holds up.
Deep dive 1 of 4
Interviewer
“Settlement is a ten-year-old Java app calling a bank’s payout API over plain HTTP, with no timeouts. How do you harden it?”
Your move. Pick an approach:
Deep dive 2 of 4
Interviewer
“Five services, all in Go, one team. An engineer wants a service mesh for retries and metrics. What do you say?”
Your move. Pick an approach:
Deep dive 3 of 4
Interviewer
“Gateway → orders → payments → bank. Each app already makes 3 attempts, and you’re adding Istio. How do you handle retries?”
Your move. Pick an approach:
Deep dive 4 of 4
Interviewer
“800 pods in Go, Java and Node, and PCI wants mTLS on every call. Where should the mesh’s data plane run?”
Assume about 50 nodes. Payments needs canaries and L7 policy; most namespaces only need encryption and identity.
Your move. Pick an approach: