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:
https://github.com/hadolint/hadolint

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:

/bin/hadolint Dockerfile

For convenience we can also create an alias in our .bashrc file so we dont have to remeber full path to the binary.

Source:

• https://github.com/udacity/DevOps_Microservices
• https://github.com/hadolint/hadolint