SNMP is one of the most prevalent (and clunky) protocols still widely used on network-attached devices. But it’s a good general-purpose way to get data from lots of different makes of products in a similar way.
But Prometheus doesn’t understand SNMP. The solution is a translation service that acts a a middle-man and ’exports’ data from those devices in a way Prometheus can.
Assuming you’ve already installed Prometheus, install some SNMP tools and the exporter. If you have an error installing the mibs-downloader, check troubleshooting at the bottom.
sudo apt install snmp snmp-mibs-downloader sudo apt install -t testing prometheus-snmp-exporter
Change the SNMP tools config file to allow use of installed MIBs.
sudo sed -i 's/^mibs/# &/' /etc/snmp/snmp.conf
We need a target, so assuming you have a switch somewhere and can enable SNMP on it, let’s query the switch for its name, AKA sysName. Here we’re using version “2c” of the protocol with the read-only password “public”. Pretty standard.
# Note: app snmpwalk -v 2c -c public some.switch.address sysName SNMPv2-MIB::sysName.0 = STRING: Some-Switch
Note: If you get back an error or just the ‘iso’ prefixed value, double check your MIBs are installed.
To add this switch to the Prometheus scraper, add a new job to the
prometheus.yaml file. This job will include the targets as normal, but also the path (since it’s different than default) and an optional parameter called module that specific to the SNMP exporter. It also does something confusing - a relabel_config
This is because Prometheus isn’t actually taking to the switch, it’s talking to the local SNMP exporter service. So we put all the targets normally, and then at the bottom ‘oh, by the way, do a switcheroo’. This allows Prometheus to display all the data normally with no one the wiser.
... ... scrape_configs: - job_name: 'snmp' static_configs: - targets: - some.switch.address metrics_path: /snmp params: module: [if_mib] relabel_configs: - source_labels: [__address__] target_label: __param_target - source_labels: [__param_target] target_label: instance - target_label: __address__ replacement: 127.0.0.1:9116 # The SNMP exporter's real hostname:port.
No configuration on the exporter side is needed. Reload the config and check the target list. Then examine data in the graph section. Add additional targets as needed and the exporter will pull in the data.
These metrics are considered well known and so will appear in the database named sysUpTime and upsBasicBatteryStatus and not be prefixed with snmp_ like you might expect.
If you have something non-standard, or you simply don’t want that huge amount of data in your system, look at the link below to customize the SNMP collection with the Generator.
The snmp-mibs-downloader is just a handy way to download a bunch of default MIBs so when you use the tools, all the cryptic numbers, like “220.127.116.11.18.104.22.168.3.1” are translated into pleasant names.
If you can’t find the mibs-downloader its probably because it’s in the non-free repo and that’s not enabled by default. Change your apt sources file like so
sudo vi /etc/apt/sources.list deb http://deb.debian.org/debian/ bullseye main contrib non-free deb-src http://deb.debian.org/debian/ bullseye main contrib non-free deb http://security.debian.org/debian-security bullseye-security main contrib non-free deb-src http://security.debian.org/debian-security bullseye-security main contrib non-free deb http://deb.debian.org/debian/ bullseye-updates main contrib non-free deb-src http://deb.debian.org/debian/ bullseye-updates main contrib non-free
It may be that you only need to change one line.
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