Middle
In what cases is multi-stage assembly used?
sobes.tech AI
Answer from AI
Multi-stage builds are used to optimize the size and security of the final Docker image, as well as to separate build stages.
Main use cases:
- Reducing image size: By using different base images for dependencies and final application creation, you can exclude build tools, source code, and other unnecessary files from the final image.
- Enhancing security: A smaller image size means a smaller attack surface. Additionally, confidential information (such as SSH keys used for cloning private repositories during build) does not end up in the final image.
- Separating build stages: Different stages can compile code, build frontend assets, run tests, and only then copy necessary artifacts into the final image. This makes the Dockerfile more readable and maintainable.
- Using different base images for different tasks: For example, using an image with a Go compiler installed for building an executable, and then copying this file into a minimal Alpine image for running.
Example of a Dockerfile with multi-stage build:
# First stage: build the Go application
FROM golang:1.20 as builder
WORKDIR /app
COPY go.mod ./
COPY go.sum ./
RUN go mod download
COPY *.go ./
RUN go build -o /app/myapp
# Second stage: create a minimal image
FROM alpine:latest
WORKDIR /app
COPY --from=builder /app/myapp .
EXPOSE 8080
CMD ["./myapp"]