enhance the san upgrade/update cli

[hchenxa]

Duplicate check

• I searched existing issues and discussions and didn't find a duplicate

Problem

san update
• Check for new releases and upgrade san itself
• Support the following modes:
• san update — check and upgrade to the latest stable release
• san update --check — only check for updates, do not download
• san update --version v1..2.3 — upgrade to a specific version
• san update --force — force overwrite the local binary
• Automatically back up the current binary before upgrading
• Roll back automatically on failure

Proposed solution

Example:

$ san update --check
Current version: 1.2.3
Latest version:  1.3.0
A new release is available. Run `san update` to upgrade.

$ san update
Downloading san v1.3.0...
Backup created at /usr/local/bin/san.bak
Update successful. Please restart your shell.

Alternatives considered

No response

[hchenxa]

I think we already have below commands available

• Check for new releases and upgrade san itself
• san update — check and upgrade to the latest stable release

and below are not included:
• san update --check — only check for updates, do not download
• san update --version v1..2.3 — upgrade to a specific version
• san update --force — force overwrite the local binary
• Automatically back up the current binary before upgrading
• Roll back automatically on failure

and for update self, I was thinking if we can provide the auto-update options to enduser, we can use environment variable/configuration to control the flag, and it should able to help enduser to use the latest version when enable this flag.

and back to the commands to be support above, I have some questions here:

1. I may use the san update --version xxxx and san update --check, but we need to think about how to list the available versions here when using the san update --check, will it only show the latest version or should we provide an upgrade path to end users?
2. any reasons we should add --force here for the overwrite, I think the current behavior is to overwrite the binary, do you run any issue with the overwrite failure?
3. I am not sure if we should provide the auto backup and roll back when update the binary, since I think we should have a stable CI to make sure the package can be installed successful for each of version and it should also cover the upgrade by CI as well. if the upgrade failed, we should check the reason and fix the issues.

@yanmxa @Shaw529 any comments?

[yanmxa]

Thanks @hchenxa 👍 My take, leaning toward keeping this simple:

• --check / version listing: just show the latest version, no upgrade path. San is still a personal tool and we don't maintain packages for older releases, so the guidance is always "use the latest" — not worth building or maintaining a version list.
• --force: let's drop it. The command already overwrites the binary, so the flag adds no real behavior — it just becomes one more thing users have to remember. A smaller command surface is more valuable here.

--version is fine to keep for anyone who needs to pin a specific release. For the auto backup/rollback, I'm with you that a stable CI (covering install + upgrade for each release) is the better safeguard, so I'd keep that part minimal for now.