PerDiskStats reported from cgroups were not being surfaced into
prometheus. In order to properly correlate the metrics, we need to
assign a device label to each metric (which is the FS or device path).
Since blkio cgroup tracks devices, we create a synthetic device
`/dev/NAME` for the metric.
Assign a Device label to each PerDiskStat for the handlers up front, and
then surface the PerDiskStat values into the prometheus metrics. Report
two new metrics - total bytes read and total bytes written.
- Pull out the root container cases, since they're only relevant in the
raw container handler
- Pass parameters rather than depending on AbstractContainerInterface
Docker does not provide the rootfs path through docker inspect or statefile
and the path is dependent on the storage driver being used.
Instead of enumerating the storage drivers, we pick a pid from the container
and get the config from /proc/pid/root. Although a bit expensive, this method
works for non-docker containers too.
The current capacity and usage numbers are insufficient to figure out
actual bytes available for a non-root user for the fs. Available is the
value used by df and the one we need to track to detect low diskspace
condition.
Containers with subcontainers always report creation time to be same as the time
of creation of the latest subcontainer.
Still not an ideal solution, but accurate for most practical purposes.
/storage returns {device, mountpoint, capacity, usage} for all filesystems.
In addition, it also detect and applies label for each filesystem - currently two - "root", "docker-images".
/storage/<label> returns info about the filesystem with specific label. eg. /storage/root returns info for root filesystem.
This should make us more robust in the face of failure (at the cost of
making the failures less prominent). We allow GetStats() to return an
error and a partial result. We will process the result and report the
error.
Fixes#306.
The stats are only populated when cAdvisor is running outside network namespaces.
We'll add a different backend to retrieve the same data from within namespaces.
