Completely finished up with making the assistant detect when git-annex's binary has changed and handling the restart.
It's a bit tricky because during an upgrade there can be two assistant daemons running at the same time, in the same repository. Although I disable the watcher of the old one first. Luckily, git-annex has long supported running multiple concurrent git-annex processes in the same repository.
The surprisingly annoying part turned out to be how to make the webapp redirect the browser to the new url when it's upgraded. Particularly needed when automatic upgrades are enabled, since the user will not then be taking any action in the webapp that could result in a redirect. My solution to this feels like overkill; the webapp does ajax long polling until it gets an url, and then redirects to it. Had to write javascript code and ugh.
But, that turned out to also be useful when manually restarting the webapp (removed some horrible old code that ran a shell script to do it before), and also when shutting the webapp down.
Getting back to upgrades, I have the assistant downloading the upgrade, and running a hook action once the key is transferred. Now all I need is some platform-specific code to install it. Will probably be hairy, especially on OSX where I need to somehow unmount the old git-annex dmg and mount the new one, from within a program running on the old dmg.
Today's work was sponsored by Evan Deaubl.
Hey,
You don't have to implement any whacky DMG replacement logic for OSX upgrades. No sane user will be using the application from the DMG. They will drag the .app directory to /Applications or some non-standard location and unmount the DMG. So your upgrade logic for OSX should end up looking very similar to the upgrade logic for Linux.