This commit builds on previous work and creates an independent
worker for every liveness probe. Liveness probes behave largely the same
as readiness probes, so much of the code is shared by introducing a
probeType paramater to distinguish the type when it matters. The
circular dependency between the runtime and the prober is broken by
exposing a shared liveness ResultsManager, owned by the
kubelet. Finally, an Updates channel is introduced to the ResultsManager
so the kubelet can react to unhealthy containers immediately.
Each container with a readiness has an individual go-routine which
handles periodic probing for that container. The results are cached, and
written to the status.Manager in the pod sync path.
Add support for pluggable Docker exec handlers. The default handler is
now Docker's native exec API call. The previous default, nsenter, can be
selected by passing --docker-exec-handler=nsenter when starting the
kubelet.
This change instructs kubelet to switch to using the Runtime interface. In order
to do it, the change moves the Prober instantiation to DockerManager.
Note that most of the tests in kubelet_test.go needs to be migrated to
dockertools. For now, we use type assertion to convert the Runtime interface to
DockerManager in most tests.