Bind Exporter 0.6.0 not compatible with Bind version 9.18.12+

[bschoenbach]

Hi guys,

I noticed that starting with bind version 9.18.12+ the exporter is not capable to parse the XML output of the bind statistics channel (:8053) anymore. The exporter logs the following lines....

level=info ts=2023-03-16T13:08:31.750Z caller=bind_exporter.go:541 msg="Starting bind_exporter" version="(version=0.6.0, branch=HEAD, revision=7464905c46d60755105b3b6c25ff88e161fcae2c)" level=info ts=2023-03-16T13:08:31.750Z caller=bind_exporter.go:542 msg="Build context" build_context="(go=go1.19.3, user=root@cb284bc56c1d, date=20221110-19:23:25)" level=info ts=2023-03-16T13:08:31.750Z caller=bind_exporter.go:543 msg="Collectors enabled" collectors=server,view,tasks level=info ts=2023-03-16T13:08:31.750Z caller=tls_config.go:232 msg="Listening on" address=[::]:9119 level=info ts=2023-03-16T13:08:31.750Z caller=tls_config.go:235 msg="TLS is disabled." http2=false address=[::]:9119 level=error ts=2023-03-16T13:08:41.865Z caller=bind_exporter.go:441 msg="Couldn't retrieve BIND stats" err="failed to unmarshal XML response: strconv.ParseUint: parsing \"-1\": invalid syntax" level=error ts=2023-03-16T13:08:42.062Z caller=bind_exporter.go:441 msg="Couldn't retrieve BIND stats" err="failed to unmarshal XML response: strconv.ParseUint: parsing \"-1\": invalid syntax" level=error ts=2023-03-16T13:08:42.071Z caller=bind_exporter.go:441 msg="Couldn't retrieve BIND stats" err="failed to unmarshal XML response: strconv.ParseUint: parsing \"-1\": invalid syntax" level=error ts=2023-03-16T13:08:52.065Z caller=bind_exporter.go:441 msg="Couldn't retrieve BIND stats" err="failed to unmarshal XML response: strconv.ParseUint: parsing \"-1\": invalid syntax" level=error ts=2023-03-16T13:08:52.069Z caller=bind_exporter.go:441 msg="Couldn't retrieve BIND stats" err="failed to unmarshal XML response: strconv.ParseUint: parsing \"-1\": invalid syntax"

However, accessing the bind statistics channel manually via curl on :8053 works perfect and i can get the following xml response as you can see below attached.

stats_output.xml.txt

The only thing i noticed is that the amount of xml data is bigger on the statistic channel starting from bind 9.18.12+. Using bind 9.18.11 or older the exporter works picture perfect again

[bschoenbach]

also tried exporter version 0.4.0 and 0.5.0......the same behaviour....none works with bind 9.18.12+

[cybermcm]

Can confirm, same here. I use bind 9.19 and also not working anymore

[paketb0te]

There are negative values in the stats_output.xml file provided by @bschoenbach :

    <taskmgr>
        ...
        <tasks>
            ...
            <task>
                <name>taskpool</name>
                <references>1</references>
                <id>0x7fe65d766440</id>
                <state>idle</state>
                <quantum>-1</quantum>    <--
                <events>0</events>
            </task>
            ...
        </tasks>

The corresponding Quantum field in the Task struct is an uint64, which would explain the parsing problem very well (since we actually receive a signed integer, -1):

// Task represents a single running task.
type Task struct {
	ID         string `xml:"id"`
	Name       string `xml:"name"`
	Quantum    uint64 `xml:"quantum"`    <--
	References uint64 `xml:"references"`
	State      string `xml:"state"`
}

I am not sure how to handle that though 🤔

[SuperQ]

Should be easy enough to change this to an int64. It'd be nice if there was a code reference to prove the unit, but it's a simple enough change.

[bschoenbach]

After testing i can confirm changing Quantum type from uint64 -> int64 fixes the problem...I will raise a pull request to master

[bschoenbach]

@SuperQ @cybermcm @paketb0te @
#166

[paketb0te]

Should be easy enough to change this to an int64. It'd be nice if there was a code reference to prove the unit, but it's a simple enough change.

@SuperQ the change itself looks trivial, I was just not sure how I'd go about checking / verifying that we can actually use an int64 (e.g. if that metric were a counter, how do we handle negative values?) 🤔

[SuperQ]

@paketb0te Looking at the metrics/code. This value isn't used anywhere. It's just used to unmarshal the XML.

[dswarbrick]

@paketb0te Looking at the metrics/code. This value isn't used anywhere. It's just used to unmarshal the XML.

If we don't use that value anywhere, why do we even bother unmarshalling that field?

[SuperQ]

Probably because of the way Go does XML parsing. :-/

[dswarbrick]

@SuperQ I don't see why there should be any issue with only declaring fields / tags that we are interested in. See https://go.dev/play/p/XoXKTcjOTQL for example.

From a quick glance at the code, I suspect that bind_exporter is unmarshalling a whole bunch of stuff that it doesn't actually translate into metrics.

[SuperQ]

Yea, I don't know the history of the XML parsing.