We are experiencing a bug with the backup/restore capabilities in marathon. Specifically when using the new query parameter for v2/leader?backup=file:///... to trigger a backup, as introduced in 1.5.0. This is breaking the new dcos-backup feature being added for DC/OS 1.10.
The steps I can take to produce the error are:
1) Start a single marathon app (a simple sleeper app will do)
2) Initiate a backup and wait for it to complete:
3) Remove the marathon app
3) Abdicate leadership again (without creating a backup or initiating a restore)
4) List the set of marathon apps
The task is back!!!
For some reason marathon seems to be initiating a restore from the backup I created without me requesting it. I am also able to reproduce this in the opposite sense, where I first create a backup with no apps running, start some apps, abdicate leadership, and my apps get killed.