A minimalistic exporter of node metrics for the Prometheus monitoring system.
This is not an officially supported Google product. It's also definitely not used by Google.
There are no particularly compelling reasons to use this software over the alternatives. On a Real Computer™, the standard Prometheus node exporter is perfectly adequate, and has a much larger feature set, not to mention adoption rate. On OpenWRT, the standard community-supported package repository already contains a lightweight Lua rewrite as prometheus-node-exporter-lua, which is even smaller in disk footprint, if you don't count the Lua interpreter.
The only reason why you would need this version is if you were building for a particularly constrained system, and did not want to include the Lua interpreter, or any foreign dependencies (other than a C runtime library).
Other than that, you might choose to use it for æsthetic reasons.
If you are able to compile code for your target system of choice, and
are happy to include all collectors, you may simply compile all the
.c
files together.
You can also use the bundled Makefile
, which likely requires GNU
Make. You can comment out collectors in the Makefile to leave them out
of the build if you don't need them.
The metrics collection is highly Linux-specific. You probably won't have much luck on other operating systems.
If you're building an OpenWrt system, you can include this program by
adding the following line to your feeds.conf
file:
src-git nanoexporter https://github.com/fis/nano-exporter.git;openwrt
Then update the feed, and install the package:
./scripts/feeds update nanoexporter
./scripts/feeds install -p nanoexporter -a
The package nano-exporter
should now be available in make menuconfig
, under the "Utilities" heading.
Please report any issues on the GitHub issues page.
See CONTRIBUTING.md for details on how to contribute patches and other code.
For the most part, the produced metrics try to loosely (but not slavishly) adhere to the format used by the standard Prometheus node exporter (as of version v0.16).
This is an overview of the available collectors. See the Collector Reference below for detailed documentation, including generated metrics, labels and configuration options.
Name | Description |
---|---|
cpu |
CPU usage from /proc/stat and CPU frequency scaling data from sysfs. |
diskstats |
Disk I/O statistics from /proc/diskstats . |
filesystem |
Statistics of mounted filesystems from statvfs(2) . |
hwmon |
Temperature, fan and voltage sensors from /sys/class/hwmon . |
meminfo |
Memory usage statistics from /proc/meminfo . |
netdev |
Network device transmit/receive statistics from /proc/net/dev . |
stat |
Basic statistics from /proc/stat . |
textfile |
Custom metrics from .prom text files dropped in a directory. |
uname |
Node information returned by the uname system call. |
By default, all collectors are enabled. Use a command line argument of
the form --{collector}-off
(e.g., --cpu-off
) to selectively
disable specific collectors. Alternatively, if you explicitly enable
any collector with --{collector}-on
, only such explicitly enabled
collectors are actually enabled. You probably don't want to mix both
on
and off
flags in the same invocation.
The general command line arguments are documented below. Specific
collectors may also accept further arguments, which will always have
the prefix --{collector}-
. They are documented in the Collector
Reference section.
Flag | Description |
---|---|
--foreground |
Don't daemonize, but remain on the foreground instead. |
--pidfile=F |
After daemonizing, write the PID of the process to file at F. No effect if combined with --foreground . |
--port=X |
Listen on port X instead of the default port (9100). |
cpu
Metrics and labels:
node_cpu_seconds_total{cpu=N,mode=M}
: Number of CPU seconds spent
in various different modes, as reported in /proc/stat
. N is the
CPU index, a number between 0 and one less than the number of
(logical) CPUs in the system. The mode M is one of user
, nice
,
system
, idle
, iowait
, irq
, softirq
or steal
. There will
be one row for each CPU and each mode in the scrape.node_cpu_frequency_hertz{cpu=N}
: The current CPU clock frequency
in Hertz at the time of the scrape. This is the
cpufreq/scaling_cur_freq
value under the CPU-specific sysfs
directory.diskstats
The metrics correspond to the columns of /proc/diskstats
:
node_disk_reads_completed_total
: Total number of successfully
completed disk reads.node_disk_reads_merged_total
Total number of adjacent reads merged
together.node_disk_read_bytes_total
: Total number of bytes read from the
device.node_disk_read_time_seconds_total
: Total time spent in read
requests.node_disk_writes_completed_total
: Total number of successfully
completed disk writes.node_disk_writes_merged_total
: Total number of adjacent writes
merged together.node_disk_written_bytes_total
: Total number of bytes written to
the device.node_disk_write_time_seconds_total
: Total time spent in write
requests.node_disk_io_now
: Number of I/O operations currently in progress.node_disk_io_time_seconds_total
: Total time spent in disk I/O.node_disk_io_time_weighted_seconds_total
: Time spent in disk I/O
weighted by the number of pending operations.node_disk_discards_completed_total
: Total number of discard
operations completed successfully.node_disk_discards_merged_total
: Total number of adjacent discard
operations merged.node_disk_discarded_sectors_total
: Total number of discarded
sectors. Note that this is in sectors, not bytes, unlike the
corresponding read/write metrics.node_disk_discard_time_seconds_total
: Total time spent in discard
operations.See the kernel's Documentation/iostats.txt file for more details. The collector assumes the read/write totals are reported using a sector size of 512 bytes.
All metrics have one label, device
, containing the device name from
/proc/diskstats
.
The --diskstats-include=
and --diskstats-exclude=
command line
arguments can be used to select which devices to report on. The format
for both is a comma-separated list of device names (e.g.,
--diskstats-include=sda,sdb
). If an include list is provided, only
those devices explicitly listed are included. Otherwise, all devices
not mentioned on the exclude list are included. If the given value
ends in *
, it matches any string that begins with the part before
the *
; otherwise, the match must be exact.
By default, if the device is entirely unused (all metrics are 0), it's
omitted. Use --diskstats-keep-unused
to include even those devices.
filesystem
Metrics:
node_filesystem_size_bytes
: Total size of the filesystem.node_filesystem_free_bytes
: Number of free bytes in the
filesystem.node_filesystem_avail_bytes
: Number of free bytes available to
unprivileged users.node_filesystem_files
: Total number of inodes supported by the
filesystem.node_filesystem_files_free
: Number of free inodes.node_filesystem_readonly
: Whether the filesystem is mounted
read-only: 0
(rw) or 1
(ro).Labels:
device
: Device node path mounted at the location.fstype
: Mounted filesystem type.mountpoint
: Location where the filesystem is mounted.By default, all mounts where the device path starts with an /
are
included. Command line arguments of the form
--filesystem-{in,ex}clude-{device,type,mount}=X,Y,Z
can be used to
define comma-separated inclusion and exclusion lists for the device
path, filesystem type and mountpoint labels, respectively. Each of the
three categories is tested independently, and only if a mounted
filesystem passes all three tests, it is included in the metrics. For
each category, if an include list is specified, only the explicitly
listed values are accepted -- this overrides even the /
prefix test
for devices. If an include list is not set, all values not on the
exclusion list are accepted. If the given value ends in *
, it
matches any string that begins with the part before the *
;
otherwise, the match must be exact.
The data is derived from scanning /proc/mounts
and calling
statvfs(2)
on all lines that pass the inclusion checks.
hwmon
The hwmon
collector pulls data from all the sysfs subdirectories
under /sys/class/hwmon
. The supported entry types are temperature
(temp*
), fan (fan*
and voltage (in*
) sensors.
Metrics:
node_hwmon_temp_celsius
: Current temperature in degrees Celsius.node_hwmon_fan_rpm
: Current fan speed in RPM.node_hwmon_fan_min_rpm
: Threshold for minimum fan speed.node_hwmon_fan_alarm
: Active fan alarm signal: 0
/1
.node_hwmon_in_volts
: Input voltage measurement.node_hwmon_in_min_volts
: Lower threshold for a voltage alarm.node_hwmon_in_max_volts
: Upper threshold for a voltage alarm.node_hwmon_in_alarm
: Active voltage alarm signal: 0
/1
.All the metrics have the same two labels: chip
and sensor
. The
chip
label is derived from the sysfs directory path, while the
sensor
label designates a specific sensor on the same (logical)
chip.
The values are by default directly as reported in sysfs: there's no built-in scaling.
(TODO: potential future feature: configurable scaling via command line options.)
meminfo
The meminfo
collector exposes all the rows from /proc/meminfo
under the metric name node_memory_X
. The part X corresponds to the
label in /proc/meminfo
, with the exception that non-alphanumeric
characters are replaced with _
, and any remaining trailing _
s are
removed.
If the line in /proc/meminfo
has a kB
suffix, the suffix _bytes
is also appended to the metric name, and the value multiplied by 1024
to convert it to bytes.
netdev
Metrics and labels:
node_network_receive_X{device=D}
: Metrics related to receiving
data on network interface D.node_network_transmit_Y{device=D}
: Metrics related to sending data
on network interface D.The exact set of metrics (X
and Y
above) depends on the columns
included in your /proc/net/dev
file. A normal set is:
Receive | Transmit | Metric | Description |
---|---|---|---|
X | X | bytes |
Byte counter |
X | X | packets |
Packet counter |
X | X | errs |
Errors while receiving/transmitting |
X | X | drop |
Dropped frame count |
X | X | fifo |
? |
X | frame |
? | |
X | compressed |
? | |
X | multicast |
Byte count | |
X | colls |
Collisions while transmitting | |
X | carrier |
? |
By default, statistics are reported for all network interfaces except
the loopback interface (lo
). The --netdev-include=
and
--netdev-exclude=
options can be used to define a comma-separated
list of interface names to explicitly include and exclude,
respectively. If an include list is set, only those interfaces are
included. Otherwise, all interfaces not mentioned in the exclude
list are included. If the given value ends in *
, it matches any
string that begins with the part before the *
; otherwise, the match
must be exact.
stat
This collectors exports the following metrics from /proc/stat
:
node_boot_time_seconds
: System boot time as a Unix timestamp (seconds since 1970).node_context_switches_total
: Total number of context switches done by the system.node_forks_total
: Total number of forks since boot.node_intr_total
: Total number of interrupts serviced.node_procs_blocked
: Number of processes currently blocked for I/O.node_procs_running
: Number of processes currently in runnable state.textfile
The textfile
collector can be used to conveniently export custom
node-bound metrics. Metrics in any files ending in .prom
in the
designated directory are included in the scrape. Generally you should
write to a file with a different suffix (say .prom.tmp
) and then
atomically rename the file, to prevent the server from sending data
from incomplete metrics files.
The implementation in this program copies the file contents directly to the outgoing HTTP response. It is your responsibility to make sure the files conform to the Prometheus exposition format. The only modification done is to add a terminating newline to the file, is one is not already present.
uname
The uname
collector exports data from the eponymous system call as
labels attached to the metric node_uname_info
, which always has the
value 1. The attached labels are:
machine
nodename
release
sysname
version
See your uname(2)
man page for details of the values.