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Collecting Linux System Data

The Linux-specific system collectors run only on Linux systems. The following table describes the files that these collectors produce:

File Source Description
system/dmesg_t.out dmesg -T Contains the kernel ring buffer with timestamps.
system/free.out free -h Reports a memory usage summary.
system/fstab.out /etc/fstab Contains the filesystem table.
system/hostname.out hostname Reports the kernel hostname (gethostname).
system/hostname_fqdn.out hostname -f Reports the fully qualified hostname (the resolver canonical name).
system/hypervisor.out systemd-detect-virt Reports the hypervisor detection result.
system/ifconfig.out ifconfig -a Lists the network interfaces (legacy).
system/interfaces.out ip -o address Lists the network interfaces in one-line format.
system/io_queue_depth.out /sys/block/*/queue/nr_requests Reports the I/O queue depth of each device.
system/io_schedulers.out /sys/block/*/queue/scheduler Reports the I/O scheduler settings.
system/iostat.out iostat -x 1 5 Reports I/O statistics over 5 samples.
system/ip_addr.out ip address list Lists the IP addresses.
system/ipcs.out ipcs -a Lists the inter-process communication (IPC) resources.
system/limits.out /etc/security/limits.conf Contains the system resource limits.
system/locale_conf.out /etc/locale.conf Contains the locale configuration.
system/localectl.out localectl status Reports the locale and keymap settings.
system/lsblk.out lsblk Shows the block device layout.
system/lscpu.out lscpu Reports the CPU architecture and topology.
system/lsdevmapper.out ls -la /dev/mapper Lists the device mapper devices.
system/lsmod.out lsmod Lists the loaded kernel modules.
system/lspci.out lspci Lists the PCI devices.
system/machine_id.out /etc/machine-id Contains the machine identifier.
system/mpstat.out mpstat -P ALL 1 5 Reports per-CPU statistics.
system/netstat_stats.out netstat -s Reports protocol statistics.
system/nfsiostat.out nfsiostat Reports NFS I/O statistics.
system/numactl.out numactl --hardware Reports the NUMA node layout and memory.
system/numastat.out numastat -m Reports per-node memory allocation statistics.
system/openssl/crypto-policies-isapplied.out update-crypto-policies --is-applied Reports the crypto policy status.
system/openssl/crypto-policies-show.out update-crypto-policies --show Reports the active crypto policy.
system/openssl/fips-mode-setup.out fips-mode-setup --check Reports the FIPS mode status.
system/os_release.out /etc/os-release Contains the OS distribution information.
system/packages-apt-list-installed.out apt list --installed *postgres* Lists the APT packages (Debian and Ubuntu).
system/packages-dnf-list-installed.out dnf list installed *postgres* Lists the DNF packages (Fedora and RHEL 8 or later).
system/packages-dpkg.out dpkg -l *postgres* Lists the Debian packages.
system/packages-rpm.out rpm -qa *postgres* Lists the RPM packages.
system/packages-yum-list-installed.out yum list installed *postgres* Lists the YUM packages (RHEL and CentOS).
system/proc/cpuinfo.out /proc/cpuinfo Contains the CPU information.
system/proc/diskstats.out /proc/diskstats Contains the raw kernel I/O counters.
system/proc/loadavg.out /proc/loadavg Reports the load average.
system/proc/meminfo.out /proc/meminfo Contains the memory information.
system/proc/mounts.out /proc/mounts Lists the mounted filesystems.
system/proc/pressure_cpu.out /proc/pressure/cpu Reports CPU pressure stall information.
system/proc/pressure_io.out /proc/pressure/io Reports I/O pressure stall information.
system/proc/pressure_memory.out /proc/pressure/memory Reports memory pressure stall information.
system/proc/swaps.out /proc/swaps Reports swap space usage.
system/proc/uptime.out /proc/uptime Reports the system uptime.
system/proc/vmstat.out /proc/vmstat Reports virtual memory statistics.
system/read_ahead.out blockdev --getra /dev/* Reports the block device read-ahead settings.
system/sar.out sar -A Contains the system activity report.
system/sestatus.out sestatus Reports the SELinux status.
system/ss_listeners.out ss -tunlp Lists the listening TCP and UDP sockets.
system/ss_summary.out ss -s Reports a socket statistics summary.
system/sys/clocksource.out /sys/devices/system/clocksource/clocksource0/current_clocksource Reports the current clocksource.
system/sys/cpu_scaling_available_governors.out /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors Lists the available CPU governors.
system/sys/cpu_scaling_driver.out /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver Reports the CPU frequency scaling driver.
system/sys/cpu_scaling_governor.out /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor Reports the active CPU governor.
system/sys/energy_perf_bias.out /sys/devices/system/cpu/cpu*/power/energy_perf_bias Reports the CPU energy performance bias.
system/sys/intel_pstate.out /sys/devices/system/cpu/intel_pstate/* Reports the Intel P-state settings.
system/sys/kernel_mm_transparent_hugepage.out /sys/kernel/mm/transparent_hugepage/* Reports the transparent hugepage settings.
system/system_release.out /etc/system-release Contains the system release information.
system/systemd/list-units.out systemctl list-units --all Lists the systemd units.
system/systemd/postgresql-status.out systemctl status 'postgresql*' Reports the PostgreSQL service status.
system/timedatectl.out timedatectl status Reports the NTP synchronization and timezone settings.
system/top.out top -b -c -w 512 -n 1 Contains a process snapshot.
system/tuned/tuned-active.out tuned-adm active Reports the active tuned profile.
system/tuned/tuned-list.out tuned-adm list Lists the available tuned profiles.
system/vmstat-command.out vmstat 1 10 Reports virtual memory statistics over 10 samples.

Reading Cgroup v2 Resource Limits

radar attempts the cgroup v2 collectors on Linux and skips any collector whose source is unavailable. radar reads these files at fixed paths under /sys/fs/cgroup, so they report the cgroup v2 hierarchy mounted there. Inside a container whose cgroup namespace roots that mount at the container's cgroup, the files show the container's resource limits. On a host, the mount is the root of the hierarchy, where only cpuset.cpus.effective and memory.stat exist, so radar skips the other files. The following table describes the cgroup v2 files:

File Source Description
system/cgroup/cpu_max.out /sys/fs/cgroup/cpu.max Reports the CPU bandwidth limit (quota and period).
system/cgroup/cpu_weight.out /sys/fs/cgroup/cpu.weight Reports the CPU weight (relative share).
system/cgroup/cpuset_cpus_effective.out /sys/fs/cgroup/cpuset.cpus.effective Reports the effective CPU set.
system/cgroup/io_max.out /sys/fs/cgroup/io.max Reports the I/O bandwidth limits.
system/cgroup/memory_current.out /sys/fs/cgroup/memory.current Reports the current memory usage.
system/cgroup/memory_max.out /sys/fs/cgroup/memory.max Reports the memory limit.
system/cgroup/memory_stat.out /sys/fs/cgroup/memory.stat Reports detailed memory statistics.
system/cgroup/memory_swap_max.out /sys/fs/cgroup/memory.swap.max Reports the swap limit.
system/cgroup/pids_current.out /sys/fs/cgroup/pids.current Reports the current number of PIDs.
system/cgroup/pids_max.out /sys/fs/cgroup/pids.max Reports the PID limit.

Reading Cgroup v1 Resource Limits

radar attempts the cgroup v1 collectors on Linux and skips any collector whose source is unavailable. These files are present on hosts that mount the cgroup v1 hierarchy, in legacy or hybrid mode. The following table describes the cgroup v1 files:

File Source Description
system/cgroup-v1/cpu_cfs_period_us.out /sys/fs/cgroup/cpu/cpu.cfs_period_us Reports the Completely Fair Scheduler (CFS) scheduling period.
system/cgroup-v1/cpu_cfs_quota_us.out /sys/fs/cgroup/cpu/cpu.cfs_quota_us Reports the CFS CPU quota; a value of -1 means unlimited.
system/cgroup-v1/cpu_shares.out /sys/fs/cgroup/cpu/cpu.shares Reports the CPU shares (relative weight).
system/cgroup-v1/cpuset_cpus.out /sys/fs/cgroup/cpuset/cpuset.cpus Lists the allowed CPUs.
system/cgroup-v1/memory_limit_in_bytes.out /sys/fs/cgroup/memory/memory.limit_in_bytes Reports the memory limit.
system/cgroup-v1/memory_stat.out /sys/fs/cgroup/memory/memory.stat Reports detailed memory statistics.
system/cgroup-v1/memory_usage_in_bytes.out /sys/fs/cgroup/memory/memory.usage_in_bytes Reports the current memory usage.

Identifying the Cloud Provider and Hardware

radar attempts the cloud and hardware identity collectors on Linux and skips any collector whose source is unavailable. These files identify the cloud provider and instance type from Desktop Management Interface (DMI) data. The following table describes the cloud and hardware identity files:

File Source Description
system/cloud/bios_vendor.out /sys/class/dmi/id/bios_vendor Reports the BIOS vendor, for example Amazon EC2 or Google.
system/cloud/chassis_asset_tag.out /sys/class/dmi/id/chassis_asset_tag Reports the chassis asset tag, for example an AWS instance ID.
system/cloud/product_name.out /sys/class/dmi/id/product_name Reports the product name, for example the instance type.
system/cloud/sys_vendor.out /sys/class/dmi/id/sys_vendor Reports the system vendor.

Identifying the Container Runtime

radar attempts the container identity collectors on Linux and skips any collector whose source is unavailable. These files help identify the container runtime and environment. The following table describes the container identity files:

File Source Description
system/container/cgroup_membership.out /proc/1/cgroup Reports the cgroup membership (container signatures).
system/container/mountinfo.out /proc/1/mountinfo Reports the PID 1 mount information (overlay detection).

Detecting a Container Environment

radar detects a container environment automatically on Linux. radar collects these files only when it runs inside a container (Docker, Kubernetes, LXC or containerd). The following table describes the container detection files:

File Source Description
system/container/environment.out env \| grep Records the allowlisted environment variables HOSTNAME, CONTAINER_ID, DOCKER_HOST, ECS_CLUSTER, ECS_CONTAINER_METADATA_URI, KUBERNETES_SERVICE_HOST, KUBERNETES_SERVICE_PORT and KUBERNETES_PORT.
system/container/k8s_namespace.out /run/secrets/.../namespace Reports the Kubernetes namespace.