Deploying and monitoring a Next.js app

Launch is the start of the feedback loop

Environment variables split cleanly: values the browser needs are inlined at build time and are therefore public, and everything else stays server-side. Getting this wrong is how a secret key ends up in a client bundle, and the build will not stop you.

Synthetic tests on a fast machine tell you the best case. Field data from real users tells you what is actually happening on mid-range phones, and the gap between the two is usually the whole problem.

Have the rollback path ready before you need it. A deploy you can reverse in a minute changes how a bad release feels — an inconvenience rather than an outage.

• Track largest contentful paint, interaction to next paint, and cumulative layout shift in the field
• Alert on error rate and latency, not on server metrics alone
• Keep the previous build deployable at all times