rigContainers function
Every container rig made, whatever its lifetime or health.
The one place this filter is built. rig ls, rig prune and the
piling-up warning in useContainer all call this instead of building
the label filter themselves, so the three can never disagree about what
counts as rig's — one of them is the destructive path.
Implementation
Future<List<ContainerSummary>> rigContainers(DockerEngine engine) =>
engine.listContainers(
filters: {
'label': [rigMarkerLabel],
},
);