Ship a new major version

An app at 1.4.2 takes 2.0.0 like any other update. check also hands back the release as new_major, so the app can tell the user.

cargo run --example demo -- --major

demo –major: an app at 1.4.2 finds 2.0.0, is told it is a new major version, and installs it once its sha256 matches

running   app 1.4.2 on linux-x86_64
check     2.0.0 is out, a new major version, 10 bytes
install   ✓ the sha256 matches, swapped in place
on disk   app 2.0.0
leftover  none

Tell the user

let check = renew::check(MANIFEST_URL, RELEASE_KEY, env!("CARGO_PKG_VERSION"))?;
if let Some(update) = &check.update {
    if check.new_major.is_some() {
        println!("{} is a new major version", update.version);
    }
}

new_major is the same release as update when its major is above the running one, and None otherwise. The app decides what to do with it: say so, ask first, or install it like any update.

A new major without some platform’s binary

If 2.0.0 ships for Linux only, apps on macOS would find no binary for their platform in the newest release. List the newest release of each older major under releases, and they keep getting their own major’s updates:

{
  "version": "2.0.0",
  "platforms": { "linux-x86_64": { "url": "…", "sha256": "…", "size": 11534336 } },
  "releases": [
    { "version": "1.5.1", "platforms": { "macos-arm64": { "url": "…", "sha256": "…", "size": 9437184 } } }
  ]
}

An app at 1.4.2 on macOS gets update = 1.5.1 and new_major = None. On Linux it gets 2.0.0 and new_major = 2.0.0. When a later major has no binary for the platform, update falls back to the newest release of the running major; if that release has no binary for the platform either, check answers NoPlatformBinary. The whole manifest is signed as one file, as Sign and publish a release shows.