Support cgroup2 for docker integration

[com6056]

Describe what happened:
Docker integration fails to detect cgroup mount for cgroup2:

2021-04-13 07:22:54 UTC | PROCESS | WARN | (pkg/util/containers/providers/cgroup/cgroup_detect.go:137 in parseCgroupMountPoints) | No mountPoints were detected, current cgroup root is: /host/sys/fs/cgroup/

It is mounted though as cgroup2 filesystem type:

root@d6d9293d2d3c:/# mount | grep cgroup
cgroup2 on /sys/fs/cgroup type cgroup2 (ro,nosuid,nodev,noexec,relatime,seclabel)
cgroup2 on /host/sys/fs/cgroup type cgroup2 (ro,nosuid,nodev,noexec,relatime,seclabel)

Suspect it is because of this line only checking for cgroup filesystem type:

datadog-agent/pkg/util/containers/providers/cgroup/cgroup_detect.go

Line 121 in e081bed

if len(tokens) >= 3 && tokens[2] == "cgroup" {

Describe what you expected:
Expect it to work with cgroup2 🙌

Steps to reproduce the issue:
Setup the docker agent with a system using cgroup2.

Additional environment details (Operating System, Cloud provider, etc):
Fedora 33, Podman 3.0.1

[fede843]

Same happens in Debian 11.

[fede843]

is there a workaround yet?

[sarahhodne]

Looks like #9121 started some of the work on this, but it's yet to be fully integrated, if I'm reading the code and PR discussion correctly.

[fede843]

Hello, yes, I've been told in internal ticket, that 7.33 should have improvements on this. Let's wait for it

[JaneJeon]

Well, 7.33 is here and it still doesn't support this.

[ademar59]

in 7.33 docker stats metrics are available though container. (not docker. anymore)

Engineering has introduced some additional metrics in version 7.33.0, however, these will be included under the new container check rather than the docker check. 

This is meant to have cgroup v1 and v2 support, as well as provide a container runtime agnostic view to the metrics. 
The idea is to have standard container.* metrics rather than: docker, cri-o, containerd specific metrics.

[JaneJeon]

Hmm, I suppose it's no surprise that it doesn't work with the docker dashboard (which is a shame), but it doesn't work with the "containers" view as well (https://app.datadoghq.com/containers).

[jharris-tc]

+1 here, having the same problem. Does not show up in the containers view or the docker view.

[j0sh3rs]

Same, this issue is still ongoing. Ubuntu 21.10 on a raspberry pi 4b, Docker + Container metrics are not present in Datadog.