Upgrade templates without git incantation

[itowlson]

Fixes #990.

Some details on which I would like feedback:

• I have proposed the name spin templates upgrade rather than update. This aligns with the plugins UI, where 'update' refers to updating the catalogue and upgrade is used to actually install a new version. However, update is established in spin templates install --update (easy to alias), and is misleading if a user is moving back to an earlier version of Spin.
• I have defaulted it to upgrading templates from all known repositories. If the user wants to be selective, they can pass --ask. An alternative approach would be to prompt by default, and require --all to upgrade all without prompting. After feedback, it now prompts by default, with a --all flag to upgrade all without prompting.
• I have allowed the user to upgrade a specific repo (optionally, to a specific tag) via the --repo/--branch options. This is an exact synonym for install --update - is it worth bothering? I'm leaning against it now. (The user could pass --ask and just select the one repo, but could not then select a specific tag.)

The report at the end is a work in progress. It will not, actually, boo errors (deserve it though they might). This is now fixed: have at it.

The --ask prompt UI is via the dialoguer crate and looks like this:

I'm not much in love with it but I don't want to invest in re-implementing it. If there are better Rust terminal libraries then I'm happy to change.

Signed-off-by: itowlson ivan.towlson@fermyon.com

[rajatjindal]

prompt by default, and require --all to upgrade all without prompting

I like this one. this is also inline with our spin new --accept-defaults UX.

I have allowed the user to upgrade a specific repo (optionally, to a specific tag) via the --repo/--branch options

hm, i can see it can be useful when user is working on changing template from e.g. fork of a repo.

[mikkelhegn]

I second the "prompt by default" option. Other than that this looks good to me!

[mikkelhegn]

No approving code, just experience

[itowlson]

@rajatjindal @mikkelhegn Thanks for the feedback - it now prompts by default.

[kate-goldenring]

However, update is established in spin templates install --update (easy to alias), and is misleading if a user is moving back to an earlier version of Spin.

So are we keeping install --update for backwards compat? My vote would be to change it to install --upgrade if we are choosing to distinguish update and upgrade. Better to eliminate the confusion now than it become bothersome post 1.0

[itowlson]

Yes, if we agree that the command should be called upgrade, we should change the flag to --upgrade with an alias to --update for back compat. I was waiting for agreement on the new command name but there seems to be general acceptance. I've made that change.

(I have left the Rust field as being called update for now, because that term is widely used in the template installation code. It would be good to change it to stay in sync with the UI, but I don't want to clutter this PR with renaming noise.)

[fibonacci1729]

LGTM code-wise. I am +1 for the experience discussed above.

[rawkode]

Awesome upgrade! 💯