docs/designs/target-fail-monitoring.md

1 # Monitoring and Logging OpenBMC Systemd Target and Service Failures
9 OpenBMC uses systemd to coordinate the starting and stopping of its
10 applications. For example, systemd is used to start all of OpenBMC's initial
14 [openbmc-systemd.md][1] has a good summary of systemd and the basics of how it
17 At a high level, systemd is composed of units. For OpenBMC, the two key unit
20 There are situations where OpenBMC systemd targets fail. They fail due to a
25 critical that if a systemd target fails within OpenBMC, the user be notified.
38 state management and systemd within OpenBMC.
40 systemd provides signals when units complete and provides status on that
41 completed unit. See the JobNew()/JobRemoved() section in the [systemd dbus
55 A systemd unit that is a service will only enter into a `failed` state after all
56 systemd defined retries have been executed. For OpenBMC systems, that involves 2
61 ### Systemd Target Units
63 - Must be able to monitor any arbitrary systemd target and log a defined error
66   - Target: Choose any systemd target
83   - Critical systemd targets are ones used by phosphor-state-manager
94 ### Systemd Service Units
96 - Must be able to monitor any arbitrary systemd service within OpenBMC
142 systemd dbus signals for JobRemoved. sdeventplus will be used for all D-Bus
155 type of services to be monitored. Their failures will cause systemd targets to
163 path but it introduces more complexity to OpenBMC systemd usage which is already
176 then returns non zero to systemd, the target that service is a part of will also
182 action, cancel the systemd target. A target status of `canceled` will not result
191 [1]: https://github.com/openbmc/docs/blob/master/architecture/openbmc-systemd.md
193 [3]: https://www.freedesktop.org/wiki/Software/systemd/dbus/