gsss charm cronjob script doesn't set an appropriate status when sync wasn't started

[Vladimir Grevtsev]

Hi,

While investigating LP: #1938069 I've found an inconsistency between the charm status and the real state of things:

<show-status-log>

26 Jul 2021 16:17:02Z juju-unit executing running commands
26 Jul 2021 16:17:02Z workload maintenance Synchronising images
26 Jul 2021 16:17:02Z juju-unit idle

<gsss.log>

INFO * 07-26 16:16:02 [PID:706977] * root * ps_service_exists=True, charm_conf['use_swift']=False, swift_exists=False
INFO * 07-26 16:16:02 [PID:706977] * root * Not updating product streams service.
INFO * 07-26 16:16:02 [PID:706977] * root * Beginning image sync
INFO * 07-26 16:16:02 [PID:706977] * root * Executing command: ['juju-run', 'glance-simplestreams-sync/0', 'status-set maintenance "Synchronising images"']
INFO * 07-26 16:16:02 [PID:706977] * root * Configuring sync for url {'url': 'http://cloud-images.ubuntu.com/releases/', 'name_prefix': 'ubuntu:released', 'path': 'streams/v1/index.sjson', 'max': 1, 'item_filters': ['release~(bionic|focal)', 'arch~(x86_64|amd64)', 'ftype~(disk1.img|disk.img)']}
INFO * 07-26 16:16:02 [PID:706977] * root * Executing command: ['juju-run', 'glance-simplestreams-sync/0', 'env']
ERROR * 07-26 16:16:02 [PID:706977] * root * could not retrieve any object-store endpoints
INFO * 07-26 16:16:02 [PID:706977] * root * sync done..

The problem here is that despite of the charm-invoked script has failed (e.g sync didn't even start), the charm status wasn't reflecting this.