Production — Chapter Quiz

Question 1

1

Why separate buildApp() from app.listen()?

APerformanceBSo tests can import the app without binding a port (SuperTest)CRequired by ExpressDNo specific reason

The separation makes the app testable. Tests pass buildApp() directly to SuperTest — no real server.

Question 2

2

Production logs should be plain console.log strings.

TTrueFFalse

Production wants structured JSON logs (e.g. pino). Easy to parse, grep, ingest into log services.

Question 3

3

What does trust proxy do?

ADisables HTTPSBTells Express to use X-Forwarded-* headers so req.ip is the real client IPCEnables sessionsDConfigures CORS

Behind a reverse proxy, set app.set("trust proxy", 1) so Express honors forwarded headers.

Question 4

4

What signal does a container orchestrator send before stopping a container?

ASIGINTBSIGTERMCSIGKILLDSIGHUP

SIGTERM first (graceful), then SIGKILL after a grace period. Handle SIGTERM to drain in-flight requests.

Question 5

5

Why use multi-stage Docker builds?

APerformanceBFinal image excludes dev deps and build tools — smaller, saferCRequired by DockerDNo reason

Stage 1 installs everything and builds. Stage 2 copies only the output + prod deps. The final image is half the size.

Question 6

6

Send error events to Sentry with Sentry.captureException(___).

Sentry.captureException(err) ships an error with stack + request context. Sentry's Express integration does it automatically via the error middleware too.

Question 7

7

Where should you NOT call slow code?

AIn a route handler that handles many concurrent requestsBIn a CLI scriptCIn a one-off migrationDIn tests

Sync slow code in a handler blocks every other concurrent request. Use async, or offload to a queue/worker.

Question 8

8

Which are good practices for a production deploy?

Select all that apply.

AGraceful shutdown on SIGTERMB/healthz endpointCMigrations run before new code is liveDBake secrets into the Docker imageETag images with the git SHA, not just latest

Never bake secrets into images. The rest are standard prod hygiene.

Test what you learned.