feat(compute): clone starter kit source with init --from=serviceID

[jsocol]

When we initialize an empty service with compute init --from=<serviceID>, we don't have the source code. This change attempts to look at the cloned_from metadata and use that to fetch the rest of the project.

[kpfleming]

The clone operation will pull the 'original' source directly from GitHub? Will it pull a specific commit hash to ensure that it gets the same thing that was used to initialize the service?

If it will be pulling directly from GitHub, the error handling will need to make that clear, since any failure on GitHub's part will make 'fastly compute init' fail and the user will assume it's a Fastly problem.

[fgsch]

Sorry for changing the title of this PR. I should have looked a bit more but confused by the description (or lack of) for the --from parameter.

Could we mention the serviceID in here or this was omitted on purpose?

[Integralist]

👋🏻

I feel like the --from=<ServiceID> feature is a bit misleading (dare I say... less than useful) or I guess I'm just generally a bit confused by its motivation/purpose 🤔

In my mind if I use --from=<ServiceID> then I'm expecting the code for that package to be made available to me so I can continuing developing the package. But from what I can tell this is just downloading the starter kit that the package was originally based on, and I'm not sure how that's useful.

Now if the original developer of the package had set --include-source as part of the fastly compute build subcommand, then I guess we might be able to extract the original source code from the uploaded package (e.g. download the package, and then extract code from the package.tar.gz file).

EDIT: I saw something internally that indicated this implementation might make sense when tied into something coming in the UI in the future.

[jsocol]

Could we mention the serviceID in here or this was omitted on purpose?

Sorry, I'm not totally sure I follow. Mention it where, in the PR, or somewhere in code/messaging?

[fgsch]

Could we mention the serviceID in here or this was omitted on purpose?

Sorry, I'm not totally sure I follow. Mention it where, in the PR, or somewhere in code/messaging?

In the help description:

  -f, --from=FROM            Local project directory, or Git repository URL,
                             or URL referencing a .zip/.tar.gz file, containing
                             a package template

[jsocol]

@Integralist @kpfleming @fgsch Updated with feedback addressed. After some internal discussions, there are three changes here:

1. Messaging around fetching the starter kit source has changed to make it clearer that's what we're using
2. Updated the logic to only fetch the source if the active version is 1
3. Added details to the --help text that mention service IDs and the starter kits

[Integralist]

One small requested change, otherwise LGTM.