SOLVED: os_node_exporter plugin not reading textfile collector prom files

[wstemb]

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:

/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: 

# 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? 

[wstemb]

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:

ts=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.