Best Practices For Efficient Image Building

Some of the best practices for creating a Dockerfile which optimizes image building and increases efficiency are as follows:

• Using smaller size official images: Using larger size images can lead to longer building time for the containers. It is therefore advised to utilize leaner OS releases with smaller images that just contain the essential system tools and libraries to reduce the attack surface and provide more secure images.
• Using the right privileged user: The root user will be used by default if the user isn’t specified in the Dockerfile, which poses a significant security concern as your application doesn’t typically require a root user. Simply add the USER directive to the Dockerfile to utilize that user to run the program to avoid this by creating a dedicated user and a dedicated group.
• Using Multi-Stage Builds: This enables us to have reproducible builds inside the container. The basic idea is to separate the build stage from the runtime stage.
• Decoupling applications: Each container should only do one thing. It is simpler to scale horizontally and reuse containers when applications are decoupled into several containers.
• Scanning for Security Vulnerabilities: By running the docker scan command we can scan our images for security vulnerabilities and make it safer.
• Reducing the number of layers: The order of instructions in a Dockerfile plays a very important role. Grouping several commands together will decrease the number of levels because RUN, COPY, ADD, and other instructions will add a new container layer.
• Updating images frequently: It is a general security best practice to use the most recent security updates because new security flaws are continually being found. Don’t use the latest version since it might not be stable but use the latest stable version.
• Avoid unnecessary packages: Refrain from installing unnecessary packages just because they might seem good to have. It will result in an image having less complexity and reduced dependencies.
• Do not expose secrets: Do not add credentials or secrets in the Dockerfile. Add it to the .dockerignore file instead, for using sensitive information.

Docker is an open-source platform that enables developers to build, distribute, operate, update, and manage containers.