Techniques like multi-stage builds and minimizing layers to create smaller images.
Creating small Docker images is a critical best practice. Smaller images are faster to pull from registries, quicker to deploy, and have a smaller attack surface, which enhances security. One of the most effective techniques for this is using multi-stage builds. A multi-stage build involves using multiple `FROM` instructions in a single Dockerfile. You can use one stage with a full-featured build environment (e.g., one with a compiler, build tools, and all dependencies) to compile your application or build your assets. Then, in a final, separate stage, you start from a minimal base image (like `alpine` or a `distroless` image) and use `COPY --from=<build_stage_name>` to copy only the compiled application binary or necessary artifacts from the build stage. This ensures that your final production image contains only your application and its exact runtime dependencies, leaving all the build tools and intermediate files behind. Another key practice is to minimize the number of layers by chaining related `RUN` commands together using `&&`. For example, instead of multiple `RUN` commands for updating apt and installing packages, combine them into one: `RUN apt-get update && apt-get install -y ...`. Also, remember to clean up caches and temporary files within the same `RUN` command to prevent them from being stored in the image layer.