92 lines
4.6 KiB
Markdown
92 lines
4.6 KiB
Markdown
# chrony Input Plugin
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Get standard chrony metrics, requires chronyc executable.
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Below is the documentation of the various headers returned by `chronyc tracking`.
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- Reference ID - This is the refid and name (or IP address) if available, of the
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server to which the computer is currently synchronised. If this is 127.127.1.1
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it means the computer is not synchronised to any external source and that you
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have the ‘local’ mode operating (via the local command in chronyc (see section local),
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or the local directive in the ‘/etc/chrony.conf’ file (see section local)).
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- Stratum - The stratum indicates how many hops away from a computer with an attached
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reference clock we are. Such a computer is a stratum-1 computer, so the computer in the
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example is two hops away (i.e. a.b.c is a stratum-2 and is synchronised from a stratum-1).
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- Ref time - This is the time (UTC) at which the last measurement from the reference
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source was processed.
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- System time - In normal operation, chronyd never steps the system clock, because any
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jump in the timescale can have adverse consequences for certain application programs.
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Instead, any error in the system clock is corrected by slightly speeding up or slowing
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down the system clock until the error has been removed, and then returning to the system
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clock’s normal speed. A consequence of this is that there will be a period when the
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system clock (as read by other programs using the gettimeofday() system call, or by the
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date command in the shell) will be different from chronyd's estimate of the current true
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time (which it reports to NTP clients when it is operating in server mode). The value
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reported on this line is the difference due to this effect.
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- Last offset - This is the estimated local offset on the last clock update.
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- RMS offset - This is a long-term average of the offset value.
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- Frequency - The ‘frequency’ is the rate by which the system’s clock would be
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wrong if chronyd was not correcting it. It is expressed in ppm (parts per million).
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For example, a value of 1ppm would mean that when the system’s clock thinks it has
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advanced 1 second, it has actually advanced by 1.000001 seconds relative to true time.
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- Residual freq - This shows the ‘residual frequency’ for the currently selected
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reference source. This reflects any difference between what the measurements from the
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reference source indicate the frequency should be and the frequency currently being used.
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The reason this is not always zero is that a smoothing procedure is applied to the
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frequency. Each time a measurement from the reference source is obtained and a new
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residual frequency computed, the estimated accuracy of this residual is compared with the
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estimated accuracy (see ‘skew’ next) of the existing frequency value. A weighted average
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is computed for the new frequency, with weights depending on these accuracies. If the
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measurements from the reference source follow a consistent trend, the residual will be
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driven to zero over time.
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- Skew - This is the estimated error bound on the frequency.
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- Root delay -This is the total of the network path delays to the stratum-1 computer
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from which the computer is ultimately synchronised. In certain extreme situations, this
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value can be negative. (This can arise in a symmetric peer arrangement where the computers’
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frequencies are not tracking each other and the network delay is very short relative to the
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turn-around time at each computer.)
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- Root dispersion - This is the total dispersion accumulated through all the computers
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back to the stratum-1 computer from which the computer is ultimately synchronised.
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Dispersion is due to system clock resolution, statistical measurement variations etc.
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- Leap status - This is the leap status, which can be Normal, Insert second,
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Delete second or Not synchronised.
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### Configuration:
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```toml
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# Get standard chrony metrics, requires chronyc executable.
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[[inputs.chrony]]
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# no configuration
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```
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### Measurements & Fields:
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- chrony
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- last_offset (float, seconds)
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- rms_offset (float, seconds)
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- frequency (float, ppm)
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- residual_freq (float, ppm)
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- skew (float, ppm)
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- root_delay (float, seconds)
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- root_dispersion (float, seconds)
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- update_interval (float, seconds)
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### Tags:
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- All measurements have the following tags:
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- reference_id
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- stratum
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- leap_status
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### Example Output:
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```
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$ telegraf -config telegraf.conf -input-filter chrony -test
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* Plugin: chrony, Collection 1
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> chrony,leap_status=normal,reference_id=192.168.1.1,stratum=3 frequency=-35.657,last_offset=-0.000013616,residual_freq=-0,rms_offset=0.000027073,root_delay=0.000644,root_dispersion=0.003444,skew=0.001,update_interval=1031.2 1463750789687639161
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```
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