---

name: create-multistage-dockerfile locale: caveman-ultra source_locale: en source_commit: 82c77053 fence_basis_commit: 82c77053 translator: "Julius Brussee homage — caveman" translation_date: "2026-04-19" description: > Create multi-stage Dockerfiles that separate build and runtime environments for minimal production images. Covers builder/runtime stage separation, artifact copying, scratch/distroless/alpine targets, and size comparison. Use when production images are too large, when build tools are included in the final image, when you need separate dev and prod images from one Dockerfile, or when deploying to constrained environments like edge or serverless. license: MIT allowed-tools: Read Write Edit Bash Grep Glob metadata: author: Philipp Thoss version: "1.0" domain: containerization complexity: intermediate language: Docker tags: docker, multi-stage, distroless, alpine, scratch, optimization

Create Multi-Stage Dockerfile

Separate build + runtime → min prod img.

Use When

• Prod imgs too large (>500MB compiled)
• Build tools (compilers, headers) in final img
• Need dev + prod from 1 Dockerfile
• Constrained env (edge, serverless)

In

• Required: Existing Dockerfile / project
• Required: Lang + build (npm, pip, go, cargo, maven)
• Optional: Runtime base (slim, alpine, distroless, scratch)
• Optional: Size budget

Do

Step 1: Build vs Runtime Deps

Cat	Build Stage	Runtime
Compilers	gcc, g++, rustc	Not needed
Pkg mgrs	npm, pip, cargo	Sometimes (interpreted)
Dev headers	-dev pkgs	Not needed
Source	Full tree	Only compiled out
Test fw	jest, pytest	Not needed

Step 2: Multi-Stage Struct

Pattern: build in fat img, copy artifacts → slim.

# ---- Build Stage ----
FROM <build-image> AS builder
WORKDIR /src
COPY <dependency-manifest> .
RUN <install-dependencies>
COPY . .
RUN <build-command>

# ---- Runtime Stage ----
FROM <runtime-image>
COPY --from=builder /src/<artifact> /<dest>
EXPOSE <port>
CMD [<entrypoint>]

Step 3: Lang-Specific

Node.js (pruned node_modules)

FROM node:22-bookworm AS builder
WORKDIR /src
COPY package.json package-lock.json ./
RUN npm ci
COPY . .
RUN npm run build && npm prune --omit=dev

FROM node:22-bookworm-slim
RUN groupadd -r app && useradd -r -g app app
WORKDIR /app
COPY --from=builder /src/dist ./dist
COPY --from=builder /src/node_modules ./node_modules
COPY --from=builder /src/package.json .
USER app
EXPOSE 3000
CMD ["node", "dist/index.js"]

Python (venv copy)

FROM python:3.12-bookworm AS builder
WORKDIR /src
RUN python -m venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .

FROM python:3.12-slim-bookworm
COPY --from=builder /opt/venv /opt/venv
ENV PATH="/opt/venv/bin:$PATH"
WORKDIR /app
COPY --from=builder /src .
RUN groupadd -r app && useradd -r -g app app
USER app
EXPOSE 8000
CMD ["python", "app.py"]

Go (static → scratch)

FROM golang:1.23-bookworm AS builder
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /server ./cmd/server

FROM scratch
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=builder /server /server
EXPOSE 8080
ENTRYPOINT ["/server"]

Rust (static musl)

FROM rust:1.82-bookworm AS builder
RUN apt-get update && apt-get install -y musl-tools && rm -rf /var/lib/apt/lists/*
RUN rustup target add x86_64-unknown-linux-musl
WORKDIR /src
COPY Cargo.toml Cargo.lock ./
RUN mkdir src && echo "fn main() {}" > src/main.rs \
    && cargo build --release --target x86_64-unknown-linux-musl \
    && rm -rf src
COPY . .
RUN touch src/main.rs && cargo build --release --target x86_64-unknown-linux-musl

FROM scratch
COPY --from=builder /src/target/x86_64-unknown-linux-musl/release/myapp /myapp
EXPOSE 8080
ENTRYPOINT ["/myapp"]

Got: Final img = runtime + compiled artifacts only.

If err: Check COPY --from=builder paths. Use docker build --target builder → debug build stage.

Step 4: Runtime Base

Base	Size	Shell	Use
scratch	0 MB	No	Static Go/Rust
gcr.io/distroless/static	~2 MB	No	Static + CA certs
gcr.io/distroless/base	~20 MB	No	Dynamic (libc)
*-slim	50-150 MB	Yes	Interpreted
alpine	~7 MB	Yes	Shell needed

Note: Alpine = musl libc. Some Python wheels / Node native mods fail. Prefer -slim (glibc) for interpreted.

Step 5: Build Args Cross Stages

ARG APP_VERSION=0.0.0

FROM golang:1.23 AS builder
ARG APP_VERSION
RUN go build -ldflags="-X main.version=${APP_VERSION}" -o /server .

FROM gcr.io/distroless/static
COPY --from=builder /server /server
ENTRYPOINT ["/server"]

Build: docker build --build-arg APP_VERSION=1.2.3 .

Note: ARG before FROM = global. Each stage must re-declare ARG to use.

Step 6: Compare Sizes

# Build both variants
docker build -t myapp:fat --target builder .
docker build -t myapp:slim .

# Compare sizes
docker images --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}" | grep myapp

Got: Prod img 50-90% smaller than build.

Check

• All stages build
• Final img no build tools
• docker run works from slim
• Size reduced vs single-stage
• COPY --from=builder paths correct
• No src leak into prod

Traps

• Missing runtime libs: Compiled code may need shared libs (libc, libssl). Test slim thoroughly.
• Broken COPY --from: Path must match exact. Debug: docker build --target builder + docker run --rm builder ls /path.
• Alpine musl: Native Node addons + some Python fail. Use -slim.
• ARG scope: Global ARG before FROM → only FROM lines. Re-declare in each stage needing it.
• No CA certs: scratch has none. Copy /etc/ssl/certs/ca-certificates.crt / use distroless.

→

• create-dockerfile — single-stage general
• create-r-dockerfile — R-specific rocker
• optimize-docker-build-cache — layer caching + BuildKit
• setup-compose-stack — compose w/ multi-stage