Unit status a the way to know what is happening with an unit. You can use the tsuru app-info -a <appname> to see the unit status:
bash
$ tsuru app-info -a tsuru-dashboard
Application: tsuru-dashboard
Repository: git@localhost:tsuru-dashboard.git
Platform: python
...
Units: 1
+------------+---------+
| Unit | State |
+------------+---------+
| 9cf863c2c1 | started |
+------------+---------+The unit state flow is:
bash
+----------+ start +---------+
| building | +---------------------+| stopped |
+----------+ | +---------+
^ | ^
| | |
deploy unit | stop
| | |
+ v RegisterUnit +
+---------+ app unit +----------+ SetUnitStatus +---------+
| created | +---------> | starting | +-------------> | started |
+---------+ +----------+ +---------+
+ ^ +
| | |
SetUnitStatus | |
| | |
v | |
+-------+ SetUnitStatus | |
| error | +-------------------+ |
+-------+ <---------------------+- `created`: is the initial status of an unit.
- `building`: is the status for units being provisioned by the provisioner, like in the deployment.
- `error`: is the status for units that failed to start, because of an application error.
- `starting`: is set when the container is started in docker.
- `started`: is for cases where the unit is up and running.
- `stopped`: is for cases where the unit has been stopped.