GitHub integration, build, and logs#

Vercel and GitHub as one organism#

The Vercel for GitHub integration is the glue of the whole workflow. Once the account is connected, Vercel watches the repository and reacts to every push and PR — without manually triggering deploys. At ProfessNet it is what connects GitHub Actions with the deploys of the ZEUS frontend.

What the integration gives you#

Feature	Effect
Auto-deploy from main	Push = a new production deploy
Preview for a PR	A comment with a link in every Pull Request
Status checks	The build status visible in the PR next to the tests
Commit ↔ deployment	Every deploy linked to a specific SHA

The build flow#

A build on Vercel has fixed stages. Knowing them helps you locate an error:

1. Cloning — fetching the repository at a specific commit.
2. Installing dependencies — npm install (with cache if package-lock has not changed).
3. Building — next build, including compilation, types, page generation.
4. Deploying — publishing the artifacts to the Edge Network.

# Locally reproduce what Vercel does
npm ci
npm run build

Reading the logs#

Build logs#

Project → Deployments → the chosen deploy → the Building tab. Here you will find the exact cause of a failed build: a TypeScript type error, a missing environment variable, an import error.

Runtime logs#

For serverless/SSR functions, use the Logs (or Runtime Logs) tab. They show requests, response times, and errors from API routes after deployment.

# Stream production logs from the CLI
vercel logs <deployment-url> --follow

Tip: When "it works for me but not on Vercel" — first run npm ci (not npm install) and npm run build locally. npm ci installs exactly the versions from package-lock.json, just as Vercel does.

Diagnosing failed deploys#

The most common causes and what to check:

Symptom	Likely cause
Type error in the build	A type error — next build stops on them
Cannot find module	A missing dependency in package.json
undefined at runtime	A missing environment variable in the given env
Build OK, page 500	A runtime error — check Runtime Logs
Incompatible version	A different Node locally than in Project Settings

Rollback and Instant Rollback#

If a fresh deploy breaks production, in Deployments point to the previous, working deploy and click Promote to Production (Instant Rollback). The rollback is instant because the previous build still exists.

Ignoring unnecessary builds#

In a monorepo not every commit concerns the frontend. The Ignored Build Step setting lets you skip the build when changes did not touch the given project — it saves time and limits.

Summary#

The GitHub↔Vercel integration automates deploys and PR previews. When something fails, read the logs: Building for compilation errors, Runtime Logs for errors after deployment. npm ci + npm run build locally reproduces Vercel's environment, and Instant Rollback saves production with one click.