improve caching and file permissions in make docker-serve

[rkm]

Hi! Is it worth revisiting #340 considering we now have a Docker lesson in incubation? Running the webpage locally can still be a bit of a pain! I'd like to contribute a Dockerfile / docker-compose script / documentation as part of my instructor training checkout process.

Edit: renamed issue after discussion below

[rkm]

Ah, I noticed that there is already a docker-serve make target for this!

It seems to run bundle install ... each time though, which can still take around 30s on successive calls even after .docker-vendor is populated (on my machine at least).

I've started working on a small improvement (gh-pages...rkm:gh-pages) which has the following advantages:

• Successive calls to make docker-serve now only take ~5s
• The image is only rebuilt when either JEKYLL_VERSION or the contents of Gemfile{,.lock} change
• Avoids leaving a root-owned ~100MB directory in your working tree, as this is now stored in the image for re-use

Would you like me to make a PR for this?

[zkamvar]

Hi @rkm,

Thank you for this! In my experience with the Jekyll Docker container, it can be a bit finnicky with the host permissions.

I had previously set up a docker container for maintaining lessons at https://github.com/carpentries/lesson-docker/#docker-container-for-lesson-maintenance that will work for the workshop-template and has a couple of advantages:

1. The versions of jekyll and ruby are pinned to github's specificatons
2. There are no longer permissions issues with root-owned or user 1000 owned files (see here for details: Use carpentries/lesson-docker for docker-serve make rule styles#461)

Let me know what you think.

[rkm]

Thanks! I'll take a look at that although the docker image seems a little heavy at ~1.4GB.

I was only hoping to contribute a small usability fix to the current workflow in this repo, so apologies if this has raised more questions than it has answered! FWIW I believe I have fixed the permissions issues on my branch, so the only remaining issue I see is that of the jekyll/ruby version pinning (which is also not addressed in the current implementation).