This guide outlines the compatibility matrix for cgroup collectors across different environments.

Version	Status	Notes
cgroup v2	✅ Fully Supported	Preferred, unified hierarchy
cgroup v1	✅ Fully Supported	Legacy, separate hierarchies

Runtime	cgroup v1	cgroup v2	Notes
Docker	✅	✅	20.10+ recommended for v2
containerd	✅	✅	1.4+ for full v2 support
CRI-O	✅	✅	Native v2 support
Podman	✅	✅	Rootless mode supported

The collectors support the two primary cgroup drivers that cover 90%+ of production deployments:

Driver	Description	Use Cases
cgroupfs	Direct filesystem driver	Docker/containerd without systemd integration
systemd	Systemd-managed cgroups	Modern Linux distributions with systemd

This pragmatic approach covers virtually all real-world container deployments without the complexity of supporting exotic configurations.

Version	Support	Notes
1.25+	✅ Full	cgroup v2 GA
1.21-1.24	✅ Full	cgroup v2 beta
1.19-1.20	✅ v1 only	Limited v2 support

Platform	Support	Notes
Linux	✅ Full Support	Primary target platform for production containers
Windows	❌ Not Supported	Would require container runtime APIs
macOS	❌ Not Supported	Not a production container platform

The cgroup-based approach is inherently Linux-specific as cgroups are a Linux kernel feature. This aligns with production reality where container workloads run on Linux servers. Future Windows support would require a different implementation using container runtime APIs.

Feature	Minimum Kernel	Recommended
cgroup v1	2.6.24+	4.4+
cgroup v2	4.5+	5.8+
PSI metrics	4.20+	5.8+

The collectors automatically detect the cgroup version by:

1. Checking for /sys/fs/cgroup/cgroup.controllers (v2 indicator)
2. Examining the mount type of /sys/fs/cgroup
3. Falling back to v1 if v2 detection fails

• Cgroup paths may change across container runtime versions
• Container IDs in paths are typically the actual container ID, but could theoretically be internal mappings
• We rely on "mostly stable" path patterns that have proven consistent in practice

• We assume the standard /sys/fs/cgroup mount location
• For non-standard mount points, the HOST_SYS environment variable can be adjusted
• Future enhancement: Parse /etc/mtab for dynamic mount discovery

• Ensure the agent has read access to /sys/fs/cgroup
• Some metrics may require CAP_SYS_ADMIN capability

• PSI (Pressure Stall Information) requires kernel 4.20+
• Some v2 controllers may be disabled by default

Different distributions may mount cgroups at:

• /sys/fs/cgroup (standard)
• /cgroup (older systems)
• Custom locations (check /proc/mounts)