perf: ship a standalone slim Docker image (~590MB → ~283MB)

[SunsetDrifter]

Why

Each deploy builds and ships a ~590 MB image carrying the full source and dependency tree. Next's standalone output ships only the traced server + static assets, roughly halving the image so docker push and the server pull are much faster. Final PR of the docs build/deploy speed series (Phase C).

What

• next.config.mjs: enable output: 'standalone'.
• Dockerfile: package only .next/standalone + .next/static + public on node:20-slim (glibc, matching the CI runner so the traced native binaries load), running node server.js. No in-image npm ci, no full source or dependency tree.
• entrypoint.sh: fix a malformed default expansion (${VAR:"none"} → ${VAR:-"none"}). Busybox sh (alpine) tolerated it; Debian dash (node:20-slim) rejects it, so the base-image change requires the fix.
• .dockerignore: root-anchor /node_modules/ so the standalone's traced node_modules is kept.

Impact

• Image ~590 MB → ~283 MB (−52%): faster registry push and server pull.
• Removes the in-image npm ci — the runner build already produces the traced dependency set.

Deploy notes

• Runtime command changes from next start to node server.js (image CMD). The server compose relies on the image's CMD/ENTRYPOINT (no overrides), passes the NEXT_PUBLIC_DOCSEARCH_* env the entrypoint substitutes, and maps to container port 3000 — no compose changes required.

Summary by CodeRabbit

• New Features

  • Switched the app’s container build to use a prebuilt standalone server output, making the runtime image smaller and simpler.
  • Updated container settings so the app binds correctly inside Docker.

• Bug Fixes

  • Fixed the fallback handling for an optional environment variable so it now defaults reliably when unset.

• Chores

  • Updated ignore rules and build configuration to better match the standalone deployment setup.

[coderabbitai]

📝 Walkthrough

Walkthrough

The Docker build was reworked to produce and package a Next.js standalone server output instead of installing dependencies and running npm start inside the image. The base image switched to node:20-slim, .dockerignore was adjusted to preserve traced node_modules, and an entrypoint.sh variable fallback syntax was corrected.

Changes

Docker standalone build migration

Layer / File(s)	Summary
Enable standalone output next.config.mjs	Adds output: 'standalone' with comments explaining the self-contained server build.
Rebuild Dockerfile around standalone artifacts docker/Dockerfile	Switches to node:20-slim, sets WORKDIR, env vars (NODE_ENV, HOSTNAME, PORT), copies .next/standalone, .next/static, public, and entrypoint.sh, then runs via entrypoint and node server.js instead of npm ci/npm run start.
Supporting ignore and entrypoint fixes .dockerignore, docker/entrypoint.sh	Root-anchors the /node_modules/ ignore rule with explanatory comments, and fixes the NEXT_PUBLIC_DOCSEARCH_INDEX_NAME default-value shell syntax to ${VAR:-"none"}.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant BuildStage
  participant Dockerfile
  participant Entrypoint
  participant NodeServer

  BuildStage->>Dockerfile: produce .next/standalone, .next/static, public
  Dockerfile->>Dockerfile: COPY standalone artifacts and entrypoint.sh
  Dockerfile->>Entrypoint: ENTRYPOINT /usr/app/entrypoint.sh
  Entrypoint->>NodeServer: CMD node server.js
  NodeServer->>NodeServer: bind HOSTNAME 0.0.0.0 PORT 3000

Loading

Poem

A rabbit hopped through Docker's den,
Trimmed the fat, packed standalone again,
node_modules traced, slim as can be,
"none" now falls back correctly,
Thump thump — ship it, friends! 🐇📦

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: switching to a standalone, slimmer Docker image with a major size reduction.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/standalone-image

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docker/Dockerfile`:
- Around line 1-30: Add a non-root runtime user to harden the Docker image: the
current Dockerfile based on node:20-slim ends with ENTRYPOINT/CMD but never
switches away from root, so the app still runs as root. Update the Dockerfile
near the existing COPY/ENTRYPOINT setup to use the built-in node user (UID 1000)
with a USER directive, and if any copied artifacts need writable ownership,
adjust the relevant COPY steps to use --chown=node:node so server.js,
.next/static, and public remain accessible.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: d4879a20-0383-4492-a88d-df75dbff5296

📥 Commits

Reviewing files that changed from the base of the PR and between 76845ec and 10403d5.

📒 Files selected for processing (4)

• .dockerignore
• docker/Dockerfile
• docker/entrypoint.sh
• next.config.mjs