The rule “Always use -y with apt-get install” is a best practice in Dockerfile development to ensure that the Docker build process is non-interactive. Dockerfiles should be designed to build without requiring any user intervention. By using the -y flag with apt-get install, you can automatically answer yes to any prompts that the installation process might produce, making the process non-interactive.
This rule is crucial because a Docker build that requires user interaction can cause problems in automated build systems. It can lead to build failures or unexpected results due to lack of user response. This is especially important in CI/CD pipelines where the Docker build process should be fully automated.
To adhere to this rule, always include the -y flag when using apt-get install in your Dockerfiles. For example, instead of writing RUN apt-get install gcc, write RUN apt-get install -y gcc. Also, to avoid potential issues with locale settings, you can use DEBIAN_FRONTEND=noninteractive in conjunction with apt-get install. For instance, RUN DEBIAN_FRONTEND=noninteractive apt-get update && apt-get install -y git.
