Reproducibly install npm dependencies in CI with npm ci (clean, lockfile-driven install)
domain: docs.npmjs.com · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Ensure the repo has a package-lock.json or npm-shrinkwrap.json committed; npm ci refuses to run without one and will not create it.
Run `npm ci` in place of `npm install` in CI/test/deploy steps. It removes node_modules first, installs exactly what the lockfile describes, and never writes to package.json or the lockfile.
If the lockfile was created with flags that change the tree shape (e.g. --legacy-peer-deps or --install-links), pass the same flags to npm ci or it will fail; commit the flag via `npm config set legacy-peer-deps=true --location=project` in the repo's .npmrc.
To speed up CI, cache the npm cache directory (~/.npm) across runs so npm ci reuses cached tarballs instead of re-downloading.
If lockfile dependencies do not match package.json, npm ci exits with an error instead of silently updating — run `npm install` locally to reconcile, then commit the updated lockfile.
Known gotchas
npm ci deletes node_modules before installing, so a partially populated node_modules cannot be reused for incremental builds.
NODE_ENV=production changes the default omit to 'dev', so devDependencies are skipped in that environment.
npm ci is NOT compatible with adding/removing individual packages — use npm install only for changing the dependency graph.
If the package-lock.json was generated with a much older npm, run npm install once with the current npm to refresh the lockfile format before running npm ci.
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