Add post on Rails "template" approach

_posts/2024-09-11-rails-projects-from-git-patches.md

@@ -0,0 +1,115 @@
+---
+title: "Generating Rails projects from Git patches"
+tags: rails git
+---
+
+A couple of weeks ago, [Joel asked][4]:
+
+> Starting a new rails app is fun!
+>
+> But after setting my bespoke set of preferred gems and config for the
+> N-hundred’th time I think it may be time for some sort of
+> template/generator/whatever.
+>
+> Any tips?
+
+So, [I mentioned the approach I've used several times recently, using `git`'s
+`format-patch` feature][5], but it really needs walking through to understand
+how this is done.
+
+Patches are how you sent commits over email, something still done on a lot of
+projects but gradually becoming more esoteric. But they're very helpful. It's a
+plain-text file with the commit information (author, time, message) and the
+change set from that commit. The key commands are [`format-patch`][6] to create
+the patches, and [`am`][7] which lets you apply them.
+
+To do this, we start with an existing, sort of "template" project that's setup
+how you'd like. But typically, I'll fetch from the last one I took this
+approach with. The key bit is having well isolated and phrased commits, like
+this:
+
+```sh
+$ git show 020090b
+commit 020090b47d75d3e77c9ee55518e5fcd9074d5c53
+Author: Nick Charlton <[email protected]>
+Date:   Mon Feb 26 14:31:59 2024 +0000
+
+    Setup a Rails app (#1)
+
+    rails new TemplateProject --database postgresql --skip-keeps \
+          --skip-action-mailbox --skip-action-text --skip-active-storage \
+          --skip-action-cable --skip-hotwire --skip-jbuilder
+
+    Plus: RSpec, FactoryBot, lograge, rack-timeout, flashes and i18n test
+    configuration.
+```
+
+Here's the first few items of `git` history for a project I put together at
+the start the year to experiment with an idea, which served as the "template
+project":
+
+```sh
+$ git log --oneline
+1f26eed (HEAD -> main, origin/main, origin/HEAD) Enable UUID primary keys (#6)
+4d8dd1c Accept connections from an external tunnel (#5)
+96f4241 Setup Ruby linting with standardrb (#4)
+a3d0e2a Setup Bundle Audit (#3)
+5bce041 Setup GitHub Actions for running tests (#2)
+020090b Setup a Rails app (#1)
+dc277a8 Initial commit; add README
+```
+
+These commits are were themselves from a another project I'd thrown together to
+experiment with something completely different, and the one before _that_ was
+when I sat down and figured out the bits I really cared about in Rails
+projects. But they're all from around the same era — it's all Rails 7.1.
+
+We can generate patches up to the "initial commit" — the first commit in a Git
+repository is special, so we want to avoid that — and then apply them to
+another project:
+
+```sh
+$ git format-patch dc277a8
+0001-Setup-a-Rails-app-1.patch
+0002-Setup-GitHub-Actions-for-running-tests-2.patch
+0003-Setup-Bundle-Audit-3.patch
+0004-Setup-Ruby-linting-with-standardrb-4.patch
+0005-Accept-connections-from-an-external-tunnel-5.patch
+0006-Enable-UUID-primary-keys-6.patch
+```
+
+I'll create a new branch, then apply the patch: `git am
+0001-Setup-a-Rails-app-1.patch`. As long as you apply them in the order they
+were written, they'll apply cleanly. If not, you can always modify the diff
+inside the patch. Then, I'll go ahead and modify that commit until it's in the
+state I want it to be:
+
+1. Change any name references to the new project,
+2. Run `bin/setup` and check it works,
+3. Run `bin/dev` and check it works,
+4. Update any gems that need updating, to save needing to do it immediately after,
+5. Finally, before merging this branch, I'll update the author/commit dates to
+   avoid confusing myself in future (e.g.: `git commit --amend --date=now`)
+
+In this example, the other patches generated are around linting, GitHub Actions
+for CI, Bundle Audit to catch vulnerable dependencies and some others like
+`UUID` primary keys. In the project I'm creating whilst writing this, I don't
+care about `UUID` so I'll just skip that but I'll want the rest.
+
+I'll caveat this approach, however, with a _you probably shouldn't do it this
+way_. From maintaining [Administrate][2] and having many ideas I'd like to try
+out, I create a lot of throw-away Rails projects.
+
+For many years, I'd used [Suspenders][1] but it went through a period where
+using it was pretty unreliable as we were struggling to keep up with Rails
+changes. Now we're at the end of 2024, we've fixed that, Suspenders is once
+again in a good place and there's been a big boon in [Rails Templates][3] too.
+But now you know you can do it completely differently, if you fancied it.
+
+[1]: https://github.com/thoughtbot/suspenders
+[2]: https://github.com/thoughtbot/administrate
+[3]: https://guides.rubyonrails.org/rails_application_templates.html
+[4]: https://mastodon.nickcharlton.net/@[email protected]/112893332849836735
+[5]: https://mastodon.nickcharlton.net/@nick/112893484600600333
+[6]: https://git-scm.com/docs/git-format-patch
+[7]: https://git-scm.com/docs/git-am