Simplify and streamline the Dockerfile

[DeeDeeG]

Scope / difficulty

Just need to update the Dockerfile. Some discussion beforehand for consensus would be great.

Impact

Would make docker-compose build run faster, and maybe make things easier to maintain; Should help the Docker config be more readable and easier to work with. Makes dependencies more obvious and more apparent what things are for what purpose.

Rationale

I realized while working on a branch that makes Vagrant usable (again, I'm not sure why I can't let go of Vagrant 🤷) that we can simplify the Docker script. A lot of apt-get update and apt-get install in the script can be removed, now that we have the nodejs, phantomjs, and yarn install scripts that install most or all of those packages regardless.

I also noticed @btyy77c's branch over at https://github.com/btyy77c/refugerestrooms/tree/dockerAlpine, that shows how much neater the script can get. I think we might want to ask for some of those things as a Pull Request, or get the okay to re-implement some of those changes. (Would want to give credit in the commit messages.)

Proposal

I think we should try some simplified Dockerfiles and discuss which is the best direction to go.

OR just make a pull request using some progress or improvements from the aforementioned branches:

• https://github.com/DeeDeeG/refugerestrooms/tree/cleanup-Dockerfile
• https://github.com/btyy77c/refugerestrooms/tree/dockerAlpine
  And discuss there.

How to actually do this:

• Consider improvements that can be made to the Dockerfile. See branches that are linked above for ideas.
• Probably merge Replace ruby base-image in Dockerfile with slimmer version #504.
  • It's a little late, but we could consider https://github.com/btyy77c/refugerestrooms/tree/dockerAlpine as an alternative to Replace ruby base-image in Dockerfile with slimmer version #504, but I think that would be unkind this late in review for that PR. Another downside is, we would be working with Alpine, which is a tad less familiar than Debian (which in turn is almost identical to working with Ubuntu). But we don't need to mess with the Dockerfile very often, so I don't think that's a big issue.
• Latstly, implement improvements by submitting the updated Dockerfile as a pull request.

OR

• Same as above, but start with the pull request and discuss and potentially make changes from there.

[DeeDeeG]

Speed comparison (docker-compose build on Ubuntu):

• After downloading the ruby 2.3.7base image, our develop branch built in 6 minutes (and 0 seconds) on my computer. @81bd2d0

Compared to...

• 5 minutes and 27 seconds: btyy77c:dockerAlpine @393cf46
• 5 minutes and 31 seconds: DeeDeeG:cleanup-Dockerfile @cb258ad
• 6 minutes and 11 seconds: DeeDeeG:dockerAlpine-2.5.3 @4a26021
• 6 minutes and 37 seconds: DeeDeeG:update-Dockerfile-2 @0626c44
• 6 minutes and 58 seconds: RefugeRestrooms:update-Dockerfile @7bca310
• 8 minutes and 12 seconds: DeeDeeG:slim-docker-image-optimized @ac30878
• 10 minutes and 33 seconds: darpr:slim-docker-image * @b7ecb5b

---

* (The branch with the 2.3.7-slim base image needs to download more packages than 2.3.7 non-slim, since it "slims down" by including less packages. Downloading and installing packages is slow. Still, this could be optimized by cleaning up the Dockerfile. This branch is equivalent to develop just with the slim ruby base image.)

[DeeDeeG]

Size of built images:

refugerestrooms_web   latest      . . .      1.5GB    #  develop
refugerestrooms_web   latest      . . .      1.48GB   #  cleanup-Dockerfile
refugerestrooms_web   latest      . . .      1.17GB   #  slim-docker-image
refugerestrooms_web   latest      . . .      1.02GB   #  slim-docker-image-optimized
refugerestrooms_web   latest      . . .      791MB    #  dockerAlpine
refugerestrooms_web   latest      . . .      763MB    #  update-Dockerfile
refugerestrooms_web   latest      . . .      743MB    #  dockerAlpine-2.5.3
refugerestrooms_web   latest      . . .      729MB    #  update-Dockerfile-2

Size of base images:

ruby          2.3.7               . . .      941MB    #  Regular (debian) ruby base image
ruby          2.3.7-slim          . . .      254MB    #  Slim (debian) ruby base image
ruby          2.5.3-slim          . . .      129MB    #  Slim (debian) ruby base image (2.5.3)
ruby          2.3.7-alpine3.7     . . .      94.4MB   #  Alpine ruby base image
ruby          2.5.3-alpine3.7     . . .      43.7MB   #  Alpine ruby base image (2.5.3)

[DeeDeeG]

I have a branch where I updated the Dockerfile to be simpler, build a smaller image, and build faster. (This branch is still based on the ruby:2.5.3-slim Docker image).

Here's the link to the branch: https://github.com/RefugeRestrooms/refugerestrooms/blob/update-Dockerfile/Dockerfile

The charts in the previous two comments are updated to show how it stacks up.

This is the second-fastest build time I've recorded out of the various Dockerfile configurations, at 7 minutes and 48 seconds. (Behind only the Alpine Linux-based image for Ruby 2.5.3.)

And it produces the third-smallest image in terms of disk space, at 827 MB. (Again, behind only the two Alpine Linux-based images.)

It still uses a larger base image than Alpine, though, at 179 MB for ruby-2.5.3-slim, vs 94.4 MB for 2.3.7-alpine3.7 or 45.5MB for 2.5.3-alpine3.7. So it presumably takes a bit longer to download on slow or intermittent networks, or uses a bit more of a limited data plan.

I would say the slim (debian-based) image is fine, especially with the improved Dockerfile in update-Dockerfile, but the Alpine image would be somewhat better for faster build speed, and for lower network usage. As long as it doesn't cause issues of some kind, and so far I haven't seen anything come up.

That said, Debian is still more familiar than Alpine, and I would find it more reassuring to work with. So there is that trade-off.

Edit: I re-ran the builds with a little more consistent approach. All the data are updated in the charts.