I installed the os_node_exporter plugin, and it is working, it is serving data from opnsense to prometheus and grafana.
The problem (or my lack of knowledge) is that, although the flag "--collector.textfile.directory=/var/tmp/node_exporter" is here (as seen from "ps aux | grep node"), the plugin is not reading nor including content of *.prom files placed in this directory:
Quote/var/tmp/node_exporter # ls -al
total 12
drwxr-xr-t 2 nobody nobody 512 Feb 5 13:21 .
drwxrwxrwt 6 root wheel 512 Feb 5 13:05 ..
-rw-r--r-- 1 nobody nobody 521 Feb 5 12:39 myfile.prom
When I look at the
http://fw_IP_ADDR:9100/metrics, the rows from myfile.prom are not here, instead I can find:
Quote# HELP node_scrape_collector_duration_seconds node_exporter: Duration of a collector scrape.
# TYPE node_scrape_collector_duration_seconds gauge
...
node_scrape_collector_duration_seconds{collector="textfile"} 0.000197219
...
# HELP node_scrape_collector_success node_exporter: Whether a collector succeeded.
# TYPE node_scrape_collector_success gauge
...
node_scrape_collector_success{collector="textfile"} 1
...
# HELP node_textfile_scrape_error 1 if there was an error opening or reading a file, 0 otherwise
# TYPE node_textfile_scrape_error gaugedata
node_textfile_scrape_error 1
Same behaviour on 24.7 or 25.1 firewall.
So there must be some read errors.
As seen in upper quote, the file is inside the /var/tmp/node_exporter directory, it has the prom extension and i changed owner to nobody:nobody since the process is working under this user. The documentation on plugin github is weak about this, somebody has some advice?
Resolved.
It was the trailing whitespace in the myspace.prom file to cause the error.
I killed the node_exporter process and restarted it from CLI. After the starting lines, I got the error:
Quotets=2025-02-06T11:14:06.216Z caller=textfile.go:245 level=error collector=textfile msg="failed to collect textfile data" file=myfile.prom err="failed to parse textfile data from \"/var/tmp/node_exporter/myfile.prom\": text format parsing error in line 3: expected integer as timestamp, got \"\""
Searching the web, I found: https://github.com/prometheus/common/issues/33. In short: the node-exporter textfile parser does not tolerate trailing whitespaces.