In what cases is it recommended to use multi-stage Docker builds and how does it help optimize the process?

Multistage Docker build is recommended when you need to create a compact and optimized image by separating the build and runtime stages of the application. For example, in the first stage, the application is built using all necessary tools and dependencies, and in the second stage, a minimal image is created into which only the compiled artifacts are copied.

This helps to:

• reduce the size of the final image by excluding unnecessary files and build tools;
• increase security, as development tools are not present in the final image;
• speed up deployment and container startup.

An example Dockerfile with multistage build:

# Build stage
FROM maven:3.8-jdk-11 AS builder
WORKDIR /app
COPY . .
RUN mvn clean package

# Runtime stage
FROM openjdk:11-jre-slim
WORKDIR /app
COPY --from=builder /app/target/myapp.jar ./
CMD ["java", "-jar", "myapp.jar"]