msiebuhr / prometheus-mdns-sd

mDNS/ZeroConf/Bonjour service discovery for Prometheus

Prometheus mDNS service discovery

Discovers mDNS (a.k.a. ZeroConf, a.k.a. Bonjour) service announcements under _prometheus-http._tcp and _prometheus-https._tcp for ad-hoc discovery of devices on LAN networks.

Install & running

go install github.com/msiebuhr/prometheus-mdns-sd

Run it

prometheus-mdns-sd -out /etc/prometheus/mdns-sd.json

And in prometheus.yml something along these lines:

- job_name: mdns-sd
  scrape_interval: 30s
  scrape_timeout: 10s
  metrics_path: /metrics
  scheme: http
  file_sd_configs:
  - files:
    - /etc/prometheus/mdns-sd.json
    refresh_interval: 5m

It resolves the raw IP's (the Go DNS resolver doesn't always understand RFC6762/RFC6763's .local names) and captures the port-number and hostname for later re-labeling.

Clients

Manually create service announcement (OS X):

dns-sd -R "My test server with metrics-endpoint" _prometheus-http._tcp. . 9000 path=/metrics

And there's some code for arduino/esp8266.

Related reading

• Initial PR to get mDNS SD into Prometheus: prometheus/prometheus#1903

prometheus-mdns-sd's Issues

Client code

Make a client implementation, so it'll be easy to advertise programs to be scraped.

(Bonus feature: Make a CLI program that can advertise any service, possibly as a wrapper: prometheus-mdns-advertise ./my-program-with-metrics).

No LICENSE file

What's the project license? It does not come with a LICENSE file.

Look at https://github.com/fabxc/prom_sd_example for config-writing stuff

The current re-use of Prometheus' internals carries a lot of baggage and so on.

https://github.com/fabxc/prom_sd_example seem to have some quick and sane stuff to be inspired by...

Only write file when something actually changed

... so Prometheus doesn't have to re-load all the time ...

(Can we be annoying and just check the raw JSON matches up?)

Sometimes has double entries

[
	{
		"targets": [
			"192.168.2.22:8080"
		],
		"labels": {
			"__meta_foo": "bar",
			"__metrics_path__": "/other/metrics",
			"__scheme__": "https",
			"instance": "Mortens-MacBook-Pro-2.local"
		}
	},
	{
		"targets": [
			"192.168.2.22:8080"
		],
		"labels": {
			"__meta_foo": "bar",
			"__metrics_path__": "/other/metrics",
			"__scheme__": "https",
			"instance": "Mortens-MacBook-Pro-2.local"
		}
	}
]

With only one publisher running on the network...

Document full setup

Document a full setup

• Getting the file dumped correctly
• Setting up Prometheus to listen for changes on that file