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PMTA knowledge base›Configuration block§ 3.3.25

<prometheus-listener>

Serving node metrics in a standard format
A third way to find out what is going on with the node

The block opens a separate port from which the monitoring system collects metrics. It appeared in PowerMTA 5.5. The block name is the address and port: 0/0 means all addresses of the machine, and a range can be given too — then the engine takes one matching address and writes which one to the log.

There is only one block per node. Metrics cannot be split by address or served to two systems on different ports.

The format is standard, and that is the main difference from the two other surfaces: the management interface serves its own format, accounting its own, while here it is what a ready-made monitoring system understands without a translator.

What is served is not the same as what the monitor shows. Besides traffic, connections and queue depth, there are error counters split into recipient level and queue level, and two delay summaries — the conversation and the time to the first attempt.

The vendor calls the cost negligible — but with a caveat: it applies to serving the metrics itself, not to track-time-first-attempt, which has its own cost in disk access.

Example configuration
# the whole block is one name line; the content is optional
<prometheus-listener 0/0:9090></prometheus-listener>

# delay values are opened separately, with node-level lines
track-inbound-perf-stats true
track-outbound-perf-stats true
track-time-first-attempt true
The block by itself serves traffic, connections, queue and errors. The three lines below add delay summaries to them — without them the delay metrics are empty.
yellow — — directive names, blue — blocks. They are highlighted the same way in the text of the card.
Block directives: 1
Monitoring 1
time-first-attempt-domains-fileA file of receivers for which the metric is broken out separately
Compatibility
PowerMTA 6.0
described in the manual of this version · platform: any
The vendor does not state the first version for every directive — there is no note here. The name also appears in the 5.0 edition of the manual.
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Related entries

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Referenced from

track-inbound-perf-statsGlobalThe only place this value goes to; without the block, counting goes into the void. § 3.3.1.43track-outbound-perf-statsGlobalThe only place this value goes to; without the block, counting goes into the void. § 3.3.1.44

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What else to read

3 articles

◇What the node tells about itself and through which channelsSeven observation surfaces: the web monitor, the console in four formats, the log, accounting, accounting search, metrics and export to external analytics.◇Two inbound report processors and what to do with themBounces by message and complaints are parsed by two identically structured blocks; each has its own address list and its own pair of decisions about the message’s fate.◇Five ways for a queue to hand off a messageA queue does not have to use SMTP: it can write to a file, run a program, call over HTTP or discard.

In the Hub
Cost of a mistake
reversible: harms only while it is set
Scenarios
Collect telemetry