Self-update script for Beaglebone software

[mryall-mawson]

Going down to Tech Lab to do software updates is a bit of a pain, so we should add a self-update capability to the code which can pull new releases from GitHub.

[mryall-mawson]

Looking at using this self_update Rust module which seems to have some nice features.

[mryall-mawson]

This is done. Releases are created using package.sh script in the root of the project, then you need to create a release on GitHub manually and upload the tar.gz file from target/release/.

Running uts-update on the Beaglebone will trigger a self-update to pull down the latest release from GitHub, and systemd should restart all the services.

This update mechanism is designed for updating the binaries and webapp code. Other changes are intentionally not supported:

• systemd and nginx config are not included, because updating them requires a daemon-reload
• environment variables are not updated because they should be configured on a per-machine basis
• the distribution includes an example programs TOML file, but does not update the usual install location of the actual programs.

One minor issue with the update code is that it seems to require a description ("body") to be set for the release on GitHub otherwise it doesn't see it. So if uts-update is not picking up a new release, that may be the reason.