Various package and software management applications require manual input for execution confirmation by default. This confirmation is usually
required when installing, updating, or removing programs and packages. General consent can be given to execute the command without manual input.
Why is this an issue?
Suppose a package manager invocation is part of a script that is executed automatically, and non-interactive mode is not enabled. Then, execution
is aborted because there is no confirming manual input. As a result, instructions, such as installation or update of packages, cannot be performed in
an automated way. This applies, among others, to the package manager used in Debian-based systems, Advanced Package Tool (APT).
How can I fix it?
Code examples
Noncompliant code example
RUN apt-get install ca-certificates
RUN aptitude install ca-certificates
RUN apt install ca-certificates
Here each line represents a package installation command command for the most popular package managers. Each of them is trying to perform an
installation in interactive mode, it will wait for prompt that will never come, so it will result in aborted execution.
Compliant solution
RUN apt-get -y install ca-certificates
RUN aptitude -y install ca-certificates
RUN apt -y install ca-certificates
Here in each line we added the option -y, it will assume yes to all prompts and continue execution.
How does this work?
If the -y flag is set, no manual input is expected, and the package manager can run non-interactively. For apt and
apt-get, the long versions --yes and --assume-yes also exist. For aptitude, the long version
--assume-yes exists.
Resources
Documentation
