Migrating to a Hardened Image

You know the image you want: the DHI Node.js variants. Now you'll rewrite the Dockerfile into a multi-stage build that uses the -dev variant to install dependencies and the minimal distroless runtime variant to actually run the app.

Note

The Dockerfile below pulls hardened images directly from the DHI registry at dhi.io. Make sure you're authenticated (docker login dhi.io) with an account entitled to Docker Hardened Images.

✍️ Step 1: Rewrite the Dockerfile

Replace the contents of Dockerfile with this hardened, multi-stage version:

# ---- Build stage: the -dev variant has a shell and npm ----
FROM dhi.io/node:20-debian12-dev AS build

WORKDIR /app

COPY package*.json ./
RUN npm install --omit=dev

COPY src ./src

# ---- Runtime stage: minimal, distroless, non-root, no shell ----
FROM dhi.io/node:20-debian12 AS runtime

WORKDIR /app

# Bring over only what's needed to run the app.
COPY --from=build /app/node_modules ./node_modules
COPY --from=build /app/src ./src
COPY --from=build /app/package.json ./package.json

EXPOSE 3000

# Invoke node explicitly. Use exec form so the app is PID 1 and receives signals.
CMD ["node", "src/server.js"]

What changed — and why it matters:

Multi-stage — build tooling (npm, shell) lives only in the build stage and never ships to production.
Distroless runtime — the final image has no shell and no package manager. Even with code execution, an attacker can't drop into a shell.
Non-root by default — DHI runtime images run as an unprivileged user out of the box.

🏗️ Step 2: Build the hardened image

docker build -t product-catalog:hardened .

🚀 Step 3: Run it and confirm it still works

docker run -d --rm --name catalog-hardened -p 8090:3000 product-catalog:hardened && \
sleep 2 && curl -s http://localhost:8090/health

Open it again in your browser at http://localhost:8090 to be sure.

Then stop it:

docker stop catalog-hardened

📉 Step 4: Compare the results

Look at the size difference between the vulnerable build and the hardened one:

docker images 'product-catalog' --format 'table {{.Repository}}:{{.Tag}}\t{{.Size}}'

And re-scan to confirm the CVEs are gone:

docker scout quickview product-catalog:hardened

Tip

You just turned a sprawling, root-running, hundreds-of-CVEs image into a small, non-root, near-zero-CVE one — without changing a line of application code. That's the whole point of starting from a hardened base.

The image is secure. Next, you'll prove it by inspecting the attestations baked into the DHI. ➡️