prom/node-exporter

Node exporter

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Prometheus exporter for hardware and OS metrics exposed by *NIX kernels, written in Go with pluggable metric collectors.

The https://github.com/prometheus-community/windows_exporter is recommended for Windows users. To expose NVIDIA GPU metrics, https://github.com/NVIDIA/dcgm-exporter can be used.

Installation and Usage

If you are new to Prometheus and node_exporter there is a simple step-by-step guide.

The node_exporter listens on HTTP port 9100 by default. See the --help output for more options.

Ansible

For automated installs with Ansible, there is the https://github.com/prometheus-community/ansible.

Docker

The node_exporter is designed to monitor the host system. Deploying in containers requires extra care in order to avoid monitoring the container itself.

For situations where containerized deployment is needed, some extra flags must be used to allow the node_exporter access to the host namespaces.

Be aware that any non-root mount points you want to monitor will need to be bind-mounted into the container.

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 path.rootfs as prefix to access host filesystem.

bash
docker run -d \
  --net="host" \
  --pid="host" \
  -v "/:/host:ro,rslave" \
  quay.io/prometheus/node-exporter:latest \
  --path.rootfs=/host

For Docker compose, similar flag changes are needed.

yaml
---
version: '3.8'

services:
  node_exporter:
    image: quay.io/prometheus/node-exporter:latest
    container_name: node_exporter
    command:
      - '--path.rootfs=/host'
    network_mode: host
    pid: host
    restart: unless-stopped
    volumes:
      - '/:/host:ro,rslave'

On some systems, the timex collector requires an additional Docker flag, --cap-add=SYS_TIME, in order to access the required syscalls.

Collectors

There is varying support for collectors on each operating system. The tables below list all existing collectors and the supported systems.

Collectors are enabled by providing a --collector.<name> flag. Collectors that are enabled by default can be disabled by providing a --no-collector.<name> flag. To enable only some specific collector(s), use --collector.disable-defaults --collector.<name> ....

Include & Exclude flags

A few collectors can be configured to include or exclude certain patterns using dedicated flags. The exclude flags are used to indicate "all except", while the include flags are used to say "none except". Note that these flags are mutually exclusive on collectors that support both.

Example:

txt
--collector.filesystem.mount-points-exclude=^/(dev|proc|sys|var/lib/docker/.+|var/lib/kubelet/.+)($|/)

List:

Enabled by default

Disabled by default

node_exporter also implements a number of collectors that are disabled by default. Reasons for this vary by collector, and may include:

• High cardinality
• Prolonged runtime that exceeds the 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.

Deprecated

These collectors are deprecated and will be removed in the next major release.

Perf Collector

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:

sysctl -w kernel.perf_event_paranoid=X

• 2 allow only user-space measurements (default since Linux 4.6).
• 1 allow both kernel and user measurements (default before Linux 4.6).
• 0 allow access to CPU-specific data but not raw tracepoint samples.
• -1 no restrictions.

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 perf_event_open.

By default, the perf collector will only collect metrics of the CPUs that node_exporter is running on (ie runtime.NumCPU. If this is insufficient (e.g. if you run node_exporter with its CPU affinity set to specific CPUs), you can specify a list of alternate CPUs by using the --collector.perf.cpus flag. For example, to collect metrics on CPUs 2-6, you would specify: --collector.perf --collector.perf.cpus=2-6. The CPU 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 1, 5, and 10.

The perf collector is also able to collect tracepoint counts when using the --collector.perf.tracepoint flag. Tracepoints can be found using perf list or from debugfs. And example usage of this would be --collector.perf.tracepoint="sched:sched_process_exec".

Sysctl Collector

The sysctl collector can be enabled with --collector.sysctl. It supports exposing numeric sysctl values as metrics using the --collector.sysctl.include flag and string values as info metrics by using the --collector.sysctl.include-info flag. The flags can be repeated. For sysctl with multiple numeric values, an optional mapping can be given to expose each value as its own metric. Otherwise an index label is used to identify the different fields.

Examples

Numeric values

Single values

Using --collector.sysctl.include=vm.user_reserve_kbytes: vm.user_reserve_kbytes = 131072 -> node_sysctl_vm_user_reserve_kbytes 131072

Multiple values

A sysctl can contain multiple values, for example:

net.ipv4.tcp_rmem = 4096	131072	6291456

Using --collector.sysctl.include=net.ipv4.tcp_rmem the collector will expose:

node_sysctl_net_ipv4_tcp_rmem{index="0"} 4096
node_sysctl_net_ipv4_tcp_rmem{index="1"} 131072
node_sysctl_net_ipv4_tcp_rmem{index="2"} 6291456

If the indexes have defined meaning like in this case, the values can be mapped to multiple metrics by appending the mapping to the --collector.sysctl.include flag: Using --collector.sysctl.include=net.ipv4.tcp_rmem:min,default,max the collector will expose:

node_sysctl_net_ipv4_tcp_rmem_min 4096
node_sysctl_net_ipv4_tcp_rmem_default 131072
node_sysctl_net_ipv4_tcp_rmem_max 6291456

String values

String values need to be exposed as info metric. The user selects them by using the --collector.sysctl.include-info flag.

Single values

kernel.core_pattern = core -> node_sysctl_info{key="kernel.core_pattern_info", value="core"} 1

Multiple values

Given the following sysctl:

kernel.seccomp.actions_avail = kill_process kill_thread trap errno trace log allow

Setting --collector.sysctl.include-info=kernel.seccomp.actions_avail will yield:

node_sysctl_info{key="kernel.seccomp.actions_avail", index="0", value="kill_process"} 1
node_sysctl_info{key="kernel.seccomp.actions_avail", index="1", value="kill_thread"} 1
...

Textfile Collector

The textfile collector is similar to the https://github.com/prometheus/pushgateway, 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 should be used for service-level metrics. The textfile module is for metrics that are tied to a machine.

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 using the text format. Note: Timestamps are not supported.

To atomically push completion time for a cron job:

echo my_batch_job_completion_time $(date +%s) > /path/to/directory/my_batch_job.prom.$
mv /path/to/directory/my_batch_job.prom.$ /path/to/directory/my_batch_job.prom

To statically set roles for a machine using labels:

echo 'role{role="application_server"} 1' > /path/to/directory/role.prom.$
mv /path/to/directory/role.prom.$ /path/to/directory/role.prom

Filtering enabled collectors

The node_exporter will expose all metrics from enabled collectors by default. This is the recommended way to collect metrics to avoid errors when comparing metrics of different families.

For advanced use the node_exporter can be passed an optional list of collectors to filter metrics. The parameters collect[] and exclude[] can be used multiple times (but cannot be combined). In Prometheus configuration you can use this syntax under the scrape config.

Collect only cpu and meminfo collector metrics:

  params:
    collect[]:
      - cpu
      - meminfo

Collect all enabled collector metrics but exclude netdev:

  params:
    exclude[]:
      - netdev

This can be useful for having different Prometheus servers collect specific metrics from nodes.

Development building and running

Prerequisites:

• Go compiler
• RHEL/CentOS: glibc-static package.

Building:

git clone https://github.com/prometheus/node_exporter.git
cd node_exporter
make build
./node_exporter <flags>

To see all available configuration flags:

./node_exporter -h

Running tests

make test

TLS endpoint

EXPERIMENTAL

The exporter supports TLS via a new web configuration file.

console
./node_exporter --web.config.file=web-config.yml

See the https://github.com/prometheus/exporter-toolkit/blob/master/docs/web-configuration.md for more details.