Previously, callers of `Exists()` would not know why the cGroup was or
was not existing. In one call-site in particular, the `kubelet` would
entirely fail to start if the cGroup validation did not succeed. In
these cases we MUST explain what went wrong and pass that information
clearly to the caller. Previously, some but not all of the reasons for
invalidation were logged at a low log-level instead. This led to poor
UX.
The original method was retained on the interface so as to make this
diff small.
Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>
Commit cc50aa9dfb introduced GetResourceStats, a method which collected
all the statistics from various cgroup controllers, only to discard all
of the info collected except a single value (memory usage).
While one may argue that this method can potentially be used from other
places, this did not happen since it was added 4+ years ago.
Let's streamline this code and only collect what we need, i.e. memory
usage. Rename the method accordingly.
While at it, fix pkg/kubelet/cm/cgroup_manager_unsupported.go to not
instantiate a new error every time a method is called.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
The slice of strings more precisely captures the hierarchic nature of
the cgroup paths we use to represent pods and their groupings.
It also ensures we're reducing the chances of passing an incorrect path
format to a cgroup driver that requires a different path naming, since
now explicit conversions are always needed.
The new constructor NewCgroupName starts from an existing CgroupName,
which enforces a hierarchy where a root is always needed. It also
performs checking on the component names to ensure invalid characters
("/" and "_") are not in use.
A RootCgroupName for the top of the cgroup hierarchy tree is introduced.
This refactor results in a net reduction of around 30 lines of code,
mainly with the demise of ConvertCgroupNameToSystemd which had fairly
complicated logic in it and was doing just too many things.
There's a small TODO in a helper updateSystemdCgroupInfo that was
introduced to make this commit possible. That logic really belongs in
libcontainer, I'm planning to send a PR there to include it there.
(The API already takes a field with that information, only that field is
only processed in cgroupfs and not systemd driver, we should fix that.)
Tested by running the e2e-node tests on both Ubuntu 16.04 (with cgroupfs
driver) and CentOS 7 (with systemd driver.)
This PR adds the pod-level metrics for CPU and memory stats. cAdvisor
can get all pod cgroup information so we can add this pod-level CPU and
memory stats information from the corresponding pod cgroup
