Melhorar Dockerfile utilizando o hadolint

[huogerac]

Hadolint é um linter de Dockerfile, podemos corrigir as sugestões e deixar o Dockerfile do projeto melhor...

❯ hadolint Dockerfile 
Dockerfile:8 DL3008 warning: Pin versions in apt get install. Instead of `apt-get install <package>` use `apt-get install <package>=<version>`
Dockerfile:8 DL3013 warning: Pin versions in pip. Instead of `pip install <package>` use `pip install <package>==<version>` or `pip install --requirement <requirements file>`
Dockerfile:8 DL3042 warning: Avoid use of cache directory with pip. Use `pip install --no-cache-dir <package>`
Dockerfile:17 DL4005 warning: Use SHELL to change the default shell
Dockerfile:17 SC2140 warning: Word is of the form "A"B"C" (B indicated). Did you mean "ABC" or "A\"B\"C"?
Dockerfile:29 DL3042 warning: Avoid use of cache directory with pip. Use `pip install --no-cache-dir <package>`

Como instalar hadolint no Debian:

sudo wget -O /bin/hadolint https://github.com/hadolint/hadolint/releases/download/v2.9.3/hadolint-Linux-x86_64
sudo chmod +x /bin/hadolint

#check hadolint install 
hadolint --help