Devenv init template support

[liammcdermott]

Problem

I'm developing drupal-devenv, which builds on devenv to provide Drupal development environments.

I feel the Getting Started process is less than ideal, users have to run devenv init, then edit our repo into their project's inputs and add the corresponding import. If you're new to devenv, this is all a bit opaque and gives a first impression that it requires a lot of boilerplate.

Meanwhile, the competition is ddev, where getting started is ddev config followed by ddev start. While the config step does ask some questions, the whole process is short and streamlined.

Solution

If we could provide a template for use with devenv init, with pre-configured inputs and such, users could get started just as easily as with ddev. For example, the usage might look like:

devenv init --template gitlab:woolwichweb/drupal-devenv

Then users just have to run devenv up to get a fully working Drupal development environment.

Related: #1705

[LorenzBischof]

I created a really simple implementation. May I ask why you don't just use nix flake init -t directly?

[liammcdermott]

Fantastic, thanks for working on this!

May I ask why you don't just use nix flake init -t directly?

I just assumed it wouldn't work with devenv. In particular devenv's default mode, with Flake inputs defined in devenv.yaml, and a flake file named .devenv.flake.nix. Maybe I'm wrong about that though.

Since you created a PR, I'm assuming you see the value in having the template parameter on devenv init? I believe it's less confusing for users who aren't familiar with Nix.

[LorenzBischof]

I made a quick example. You can use it with:

nix flake init -t github:LorenzBischof/devenv-issue-1718

I don't really see any benefit, other than a simpler interface. In your documentation you would also have to add --extra-experimental-features "nix-command flakes" to the command in case someone does not have the features enabled yet.

edit: I updated the example with a welcomeText which might be useful for your use case. I also noticed that the template gets cached locally. To force retrieval of the newest version use --refresh. The cache probably expires after a while, so it should not be necessary for you to document it.