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Dnsmasq DHCP collector

Overview

Dnsmasq is a lightweight, easy to configure DNS forwarder, designed to provide DNS (and optionally DHCP and TFTP) services to a small-scale network.

This collector monitors one or more Dnsmasq DHCP leases databases, depending on your configuration.

By default, it uses:

  • /var/lib/misc/dnsmasq.leases to read leases.
  • /etc/dnsmasq.conf to detect dhcp-ranges.
  • /etc/dnsmasq.d to find additional configurations.

All configured dhcp-ranges are detected automatically.

Collected metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

global

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

MetricDimensionsUnit
dnsmasq_dhcp.dhcp_rangesipv4, ipv6ranges
dnsmasq_dhcp.dhcp_hostsipv4, ipv6hosts

dhcp range

These metrics refer to the DHCP range.

Labels:

LabelDescription
dhcp_rangeDHCP range in START_IP:END_IP format

Metrics:

MetricDimensionsUnit
dnsmasq_dhcp.dhcp_range_utilizationusedpercentage
dnsmasq_dhcp.dhcp_range_allocated_leasesallocatedleases

Setup

Prerequisites

No action required.

Configuration

File

The configuration file name is go.d/dnsmasq_dhcp.conf.

The file format is YAML. Generally, the format is:

update_every: 1
autodetection_retry: 0
jobs:
- name: some_name1
- name: some_name1

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/dnsmasq_dhcp.conf

Options

The following options can be defined globally: update_every, autodetection_retry.

Config options
NameDescriptionDefaultRequired
update_everyData collection frequency.1
autodetection_retryRe-check interval in seconds. Zero means not to schedule re-check.0
leases_pathPath to dnsmasq DHCP leases file./var/lib/misc/dnsmasq.leases
conf_pathPath to dnsmasq configuration file./etc/dnsmasq.conf
conf_dirPath to dnsmasq configuration directory./etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new

Examples

Basic

An example configuration.

Config
jobs:
- name: dnsmasq_dhcp
leases_path: /var/lib/misc/dnsmasq.leases
conf_path: /etc/dnsmasq.conf
conf_dir: /etc/dnsmasq.d
Pi-hole

Dnsmasq DHCP on Pi-hole.

Config
jobs:
- name: dnsmasq_dhcp
leases_path: /etc/pihole/dhcp.leases
conf_path: /etc/dnsmasq.conf
conf_dir: /etc/dnsmasq.d

Troubleshooting

Debug mode

To troubleshoot issues with the dnsmasq_dhcp collector, run the go.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn't working.

  • Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that's not the case on your system, open netdata.conf and look for the plugins setting under [directories].

    cd /usr/libexec/netdata/plugins.d/
  • Switch to the netdata user.

    sudo -u netdata -s
  • Run the go.d.plugin to debug the collector:

    ./go.d.plugin -d -m dnsmasq_dhcp

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