Modest doc improvements (#1876)

* Modest doc improvements

Signed-off-by: Anthony D'Atri <anthony.datri@gmail.com>
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Anthony D'Atri 2020-11-25 07:46:58 -08:00 committed by GitHub
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@ -68,8 +68,25 @@ zfs | Exposes [ZFS](http://open-zfs.org/) performance statistics. | [Linux](http
### Disabled by default ### Disabled by default
The perf collector may not work by default on all Linux systems due to kernel `node_exporter` also implements a number of collectors that are disabled by default. Reasons for this vary by
configuration and security settings. To allow access, set the following sysctl collector, and may include:
* High cardinality
* Prolonged runtime that exceeds Prometheus` `scrape_interval` or `scrape_timeout`
* Significant resource demands on the host
You can enable additional collectors as desired by adding them to your
init system's or service supervisor's startup configuration for
`node_exporter` but caution is advised. Enable at most one at a time,
testing first on a non-production system, then by hand on a single
production node. When enabling additional collectors, you should
carefully monitor the change by observing the `
scrape_duration_seconds` metric to ensure that collection completes
and does not time out. In addition, monitor the
`scrape_samples_post_metric_relabeling` metric to see the changes in
cardinality.
The `perf` collector may not work out of the box on some Linux systems due to kernel
configuration and security settings. To allow access, set the following `sysctl`
parameter: parameter:
``` ```
@ -85,7 +102,7 @@ Depending on the configured value different metrics will be available, for most
cases `0` will provide the most complete set. For more information see [`man 2 cases `0` will provide the most complete set. For more information see [`man 2
perf_event_open`](http://man7.org/linux/man-pages/man2/perf_event_open.2.html). perf_event_open`](http://man7.org/linux/man-pages/man2/perf_event_open.2.html).
By default, the perf collector will only collect metrics of the CPUs that By default, the `perf` collector will only collect metrics of the CPUs that
`node_exporter` is running on (ie `node_exporter` is running on (ie
[`runtime.NumCPU`](https://golang.org/pkg/runtime/#NumCPU). If this is [`runtime.NumCPU`](https://golang.org/pkg/runtime/#NumCPU). If this is
insufficient (e.g. if you run `node_exporter` with its CPU affinity set to insufficient (e.g. if you run `node_exporter` with its CPU affinity set to
@ -96,7 +113,7 @@ configuration is zero indexed and can also take a stride value; e.g.
`--collector.perf --collector.perf.cpus=1-10:5` would collect on CPUs `--collector.perf --collector.perf.cpus=1-10:5` would collect on CPUs
1, 5, and 10. 1, 5, and 10.
The perf collector is also able to collect The `perf` collector is also able to collect
[tracepoint](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html) [tracepoint](https://www.kernel.org/doc/html/latest/core-api/tracepoint.html)
counts when using the `--collector.perf.tracepoint` flag. Tracepoints can be counts when using the `--collector.perf.tracepoint` flag. Tracepoints can be
found using [`perf list`](http://man7.org/linux/man-pages/man1/perf.1.html) or found using [`perf list`](http://man7.org/linux/man-pages/man1/perf.1.html) or
@ -126,13 +143,13 @@ perf | Exposes perf based metrics (Warning: Metrics are dependent on kernel conf
### Textfile Collector ### Textfile Collector
The textfile collector is similar to the [Pushgateway](https://github.com/prometheus/pushgateway), The `textfile` collector is similar to the [Pushgateway](https://github.com/prometheus/pushgateway),
in that it allows exporting of statistics from batch jobs. It can also be used in that it allows exporting of statistics from batch jobs. It can also be used
to export static metrics, such as what role a machine has. The Pushgateway to export static metrics, such as what role a machine has. The Pushgateway
should be used for service-level metrics. The textfile module is for metrics should be used for service-level metrics. The `textfile` module is for metrics
that are tied to a machine. that are tied to a machine.
To use it, set the `--collector.textfile.directory` flag on the Node exporter. The To use it, set the `--collector.textfile.directory` flag on the `node_exporter` commandline. The
collector will parse all files in that directory matching the glob `*.prom` collector will parse all files in that directory matching the glob `*.prom`
using the [text using the [text
format](http://prometheus.io/docs/instrumenting/exposition_formats/). **Note:** Timestamps are not supported. format](http://prometheus.io/docs/instrumenting/exposition_formats/). **Note:** Timestamps are not supported.
@ -203,6 +220,7 @@ The `node_exporter` is designed to monitor the host system. It's not recommended
to deploy it as a Docker container because it requires access to the host system. to deploy it as a Docker container because it requires access to the host system.
Be aware that any non-root mount points you want to monitor will need to be bind-mounted Be aware that any non-root mount points you want to monitor will need to be bind-mounted
into the container. into the container.
If you start container for host monitoring, specify `path.rootfs` argument. If you start container for host monitoring, specify `path.rootfs` argument.
This argument must match path in bind-mount of host root. The node\_exporter will use This argument must match path in bind-mount of host root. The node\_exporter will use
`path.rootfs` as prefix to access host filesystem. `path.rootfs` as prefix to access host filesystem.

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@ -2,15 +2,15 @@
## `ntp` collector ## `ntp` collector
This collector is intended for usage with local NTPD like [ntp.org](http://ntp.org/), [chrony](https://chrony.tuxfamily.org/comparison.html) or [OpenNTPD](http://www.openntpd.org/). This collector is intended for usage with local NTP daemons including [ntp.org](http://ntp.org/), [chrony](https://chrony.tuxfamily.org/comparison.html), and [OpenNTPD](http://www.openntpd.org/).
Note, some chrony packages have `local stratum 10` configuration value making chrony a valid server when it is unsynchronised. This configuration makes one of `node_ntp_sanity` heuristics unreliable. Note, some chrony packages have `local stratum 10` configuration value making chrony a valid server when it is unsynchronised. This configuration makes one of the heuristics that derive `node_ntp_sanity` unreliable.
Note, OpenNTPD does not listen for SNTP queries by default, you should add `listen on 127.0.0.1` configuration line to use this collector with OpenNTPD. Note, OpenNTPD does not listen for SNTP queries by default. Add `listen on 127.0.0.1` to the OpenNTPD configuration when using this collector with that package.
### `node_ntp_stratum` ### `node_ntp_stratum`
This metric shows [stratum](https://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata) of local NTPD. This metric shows the [stratum](https://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata) of the local NTP daemon.
Stratum `16` means that clock are unsynchronised. See also aforementioned note about default local stratum in chrony. Stratum `16` means that clock are unsynchronised. See also aforementioned note about default local stratum in chrony.