Hadolint is linter for Dockerfiles, it is checking if dockerfile has correct syntax (and that dockerfile is compliant with other defined rules)
Rules are defined below:
Easiest way how to make hadolint work is just to download the executable and put is in your /bin directory (download the newest version from official hadolint github)
sudo wget -O /bin/hadolint https://github.com/hadolint/hadolint/releases/download/v1.16.3/hadolint-Linux-x86_64 sudo chmod +x /bin/hadolint
Then we can start checking syntax of our dockerfile:
For convenience we can also create an alias in our .bashrc file so we dont have to remeber full path to the binary.