• This is a bug report
• This is a feature request
• I searched existing issues before opening this one

Minimal example

Consider this mini.Dockerfile

FROM alpine:3
SHELL ["/bin/bash", "-c"]
ENV NVM_DIR=/usr/local/nvm
RUN source $NVM_DIR/nvm.sh

Linting fails:

$ docker run --rm -i hadolint/hadolint:latest /bin/hadolint - < mini.Dockerfile 
/dev/stdin:4 SC1090 Can't follow non-constant source. Use a directive to specify location.

What does shellcheck say?

According to https://github.com/koalaman/shellcheck/wiki/SC1090 the fix is to put a shell comment "directive" to assist:

# shellcheck source=src/lib.sh
. "$(find_install_dir)/lib.sh"

If you don't care that ShellCheck is unable to account for the file, specify # shellcheck source=/dev/null.

But that doesn't work...

mini2.Dockerfile

FROM alpine:3
SHELL ["/bin/bash", "-c"]
ENV NVM_DIR=/usr/local/nvm
RUN # shellcheck source=/dev/null
RUN source $NVM_DIR/nvm.sh

$ docker run --rm -i hadolint/hadolint:latest /bin/hadolint - < mini2.Dockerfile 
/dev/stdin:4 SC1072 Expected a command. Fix any mentioned problems and try again.
/dev/stdin:5 SC1090 Can't follow non-constant source. Use a directive to specify location.

The old "Now you have 2 problems"...

mini3.Dockerfile

FROM alpine:3
SHELL ["/bin/bash", "-c"]
ENV NVM_DIR=/usr/local/nvm
# shellcheck source=/dev/null
RUN source $NVM_DIR/nvm.sh

$ docker run --rm -i hadolint/hadolint:latest /bin/hadolint - < mini3.Dockerfile 
/dev/stdin:5 SC1090 Can't follow non-constant source. Use a directive to specify location.

Expected behavior

Either drop the error entirely or provide a valid way to work around it.

Version

Output of hadolint --version or
docker run --rm hadolint/hadolint hadolint --version:

$ docker run --rm hadolint/hadolint:latest hadolint --version
Haskell Dockerfile Linter v1.17.0-0-g56fd3e1