The web page is by default served on http://0.0.0.0:4000/acap-documentation,
but if you cannot open this page, try localhost:4000/acap-documentation.
GitHub Pages is based on Jekyll to build and serve web pages. The acap-documentation repository builds Docker container images based on the official Jekyll Docker image to be able to test changes without having to install dependencies like Ruby and Jekyll.
To serve this page from the acap-documentation directory, it's enough to run
docker run --rm -p 4000:4000 -v "$PWD":/srv/jekyll -it doc:1 jekyll servebut in the CONTRIBUTING page the instruction is much longer, why?
The Jekyll image has permission to change the directory and sub-directories that
gets mounted with -v "$PWD":/srv/jekyll. On Unix systems it's common to
search the command history to run a recurring command and here's the nasty
thing; running the above command from home directory ~/ instead of
acap-documentation directory will change ownership of certain directories,
one of them being ~/.cache. A program affected by this is Firefox. The
change is not noted until a restart and the error is complaining on that the
profile cannot be loaded, making this a tricky problem to troubleshoot.
A quick solution is to add checks that this image can only be run from the correct directory as described in the comments of the below code block.
# Run the Docker image to serve the web page
# - Check that current directory is a git repository
# - Check that the current directory has the expected name "acap-documentation"
# or "acap-documentation-staging"
# - Run Docker image and mount the top git directory
# - If error in any of the previous steps, print a help message
ACAPDOC="$(git rev-parse --show-toplevel)" && \
{ [ "${ACAPDOC##*/}" = "acap-documentation" ] || [ "${ACAPDOC##*/}" = "acap-documentation-staging" ] ; } && \
docker run --rm -p 4000:4000 -v "$ACAPDOC":/srv/jekyll -it doc:1 jekyll serve || \
printf "\nERROR: The current directory is not acap-documentation*\n"