Make it possible to "auto-downgrade" the application on channel change

[tvanro]

• electron-builder: 11.5.0
• electron-auto-updater: 1.0.0

• Target: win32

We have separate release channels based on the configuration of the user (beta|stable).
Lets say these are the current versions:

• beta: 1.2.0-beta.4
• stable: 1.1.0

Behavior we would like to achieve:
When a user from the beta channel wants to go back to the stable channel the application should auto-update (downgrade) to the latest stable version.

Possible solutions:

1. Always update on channel change (check the current application channel with the requested channel)

GenericProvider.ts

async shouldForceUpdate(): Promise<boolean> {
  const latestChannel = this.channel
  // currentChannel how to get this?
  return latestChannel != currentChannel
}

AppUpdater.ts

const forceUpdate = await client.shouldForceUpdate()
if (!forceUpdate && !isVersionGreaterThan(latestVersion, currentVersion)) {
  this.updateAvailable = false
  if (this.logger != null) {
    this.logger.info(`Update for version ${versionInfo.version} is not available`)
  }
  this.emit("update-not-available")
  return {
    versionInfo: versionInfo,
  }
}

and small updates on all the other Providers + interface Provider

2. Add a configuration option like updateOnVersionChange or canDowngrade (better name suggestions are welcome) that will auto-update the application if latestVersion != currentVersion.

AppUpdater.ts

if ((updateOnVersionChange && latestVersion == currentVersion) || (!updateOnVersionChange && !isVersionGreaterThan(latestVersion, currentVersion))) {
  this.updateAvailable = false
  if (this.logger != null) {
    this.logger.info(`Update for version ${versionInfo.version} is not available`)
  }
  this.emit("update-not-available")
  return {
    versionInfo: versionInfo,
  }
}

Let me know if we could integrate any of these solutions with a pull request or if you have an even better proposal to achieve this "downgrade" on channel change behavior.

Thanks!

[develar]

How do we know "check the current application channel "?

[tvanro]

It would only be for GenericProvider and we could compare the (current application) channel inside resources/app-update.yml with the channel that is set inside autoUpdater.setFeedURL.

So for example we have this inside app-update.yml:

provider: generic
url: 'https://releases.test.com'
channel: beta

And we update the autoUpdater like this:

autoUpdater.setFeedURL({ provider: "generic", url: "https://releases.test.com", channel: "stable" });

This would be a solution that only affects the GenericProvider.

The other solution would be to add a configuration option like updateOnVersionChange or canDowngrade (see above).

[develar]

Relates #1182

[develar]

#1391 will be solved soon and option allowPrerelease is added. If true, downgrade will be allowed.

[develar]

allowDowngrade option is added. Defaults to true if application version contains prerelease components (e.g. 0.12.1-alpha.1, here alpha is a prerelease component), otherwise false. So, if version are not equal — we just update to versions in the update info. If you set channel or somehow else set lower version in the update info — it is your developer decision :) No need to implement at little bit complex channel check.