Best Practices

Understand build context

When executing "docker build", the current working directory is the the build context. By default, the Dockerfile is assumed to be in the current working directory.

Irrespective of where the Dockerfile is located, all recursive contents of files and directories in the current directory are sent to the Docker daemon as the build context.

Inadvertently including files that are not necessary for building an image results in a larger build context and larger image size.

This can increase the time to build the image, time to pull and push it, and the container runtime size.

Exclude with .dockerignore

Exclude files not relevant to the build with a .dockerignore file.

This file supports exclusion patterns similar to .gitignore files.

Use multi-stage builds

Multi-stage builds reduces the size of an image, without worrying about the number of intermediate layers and files.

An image is built during the final stage of the build process. The number of image layers can be minimized by leveraging build cache.

For a build that contains several layers, order them from the less frequently changed (re-use build cache) to the more frequently changed:

• Install tools you need to build your application

• Install or update library dependencies

• Generate your application

Don’t install unnecessary packages

Avoid installing extra or unnecessary packages.

This will reduce complexity, dependencies, file sizes, and build times,  Don't include a text editor in a database image.

Decouple applications

Apply the principle of "separation of concerns."

Each container should have only one concern. Decoupling applications into multiple containers makes it easier to reuse containers.