Upstart Integration

Upstart is the current init implementation in Ubuntu. It is slated for migration to systemd sometime in the future as Debian has recently opted to make it the default init implementation on Linux. Upstart is used by AVE to start various services, such as the broker, when the PC boots.

The current volatile situation with init implementations on Linux prompted a solution that does not actually make any use of “extra” features found in Upstart, compared to the classic SysV implementation. Such use would make future migration to another implementation difficult. Upstart is only used to start AVE services at boot. The lab owner must interact directly with the various services to start, restart and stop them after the PC is fully booted.

Model

All AVE services must implement this command line interface:

ave-<service> --start --force

which will be used from a corresponding Upstart rule in:

/etc/init/ave-<service>.conf

The CLI arguments must be handled like so:

• Delete any existing PID file found in /var/tmp/ave-<service>.pid.
• Start the service daemonized.
• Create /var/tmp/ave-<service>.pid.

The Upstart configuration file should normally not start the service until the local file system and full networking is available. AVE services demote their effective user ID to whatever is found in /etc/ave/user, so the file system and networking are needed to interact with the networked authentication system used at SoMC. Broker example:

# /etc/init/ave-broker.conf
description "ave-broker"

start on (filesystem and net-device-up IFACE!=lo)

console output
expect daemon

exec /usr/bin/ave-broker --start --force

Notes

• The lab owner can disable automatic start of a service at boot by commenting out the exec line in the corresponding /etc/init/ave-<service>.conf file.

• The default Upstart file for Flocker has the exec commented out. Most hosts should not run this service. (Note that Flocker’s configuration file .ave/config/flocker.json is also not created by default for the same reason, and because its contents depends very much on the local configuration of lighttpd, which AVE does not try to parse.)

• The service that starts the ADB server runs as root. (This is needed to guarantee that ADB will have sufficient permissions to claim the equipment on USB level. It also makes ADB a bit more reliable in general.) Users who want to control the life cycle of the ADB server manually should create .ave/config/adb_server.json with this content:

  { "demote":true, "persist":false }
  

  This still starts the ADB server on PC boot, but not as root and the ADB server will not be restarted automatically when it is killed.