Apache httpd

The web server: busy and idle workers, the worker scoreboard by state, and request/byte rates when ExtendedStatus is on.

Network ports to open

From the DumbMonit server (or its relay agent) to the device:

Port	Protocol	Purpose
80	TCP	Status page (HTTP, default)
443	TCP	Only if the status page is served over HTTPS

DumbMonit reads Apache’s built-in mod_status, queried with ?auto so it answers in plain Key: Value lines instead of the HTML page meant for a browser.

What it watches

All metrics are prefixed dumbmonit_apache_. The _total metrics are counters: charts and rules turn them into rates. Everything below workers_busy/workers_idle and scoreboard needs ExtendedStatus On.

Metric	What	Labels
`workers_busy`, `workers_idle`	worker processes or threads, by state
`scoreboard`	worker slots by scoreboard state	`state`
`requests_total`	requests served since Apache started
`sent_bytes_total`	bytes sent since Apache started
`uptime_seconds`	time since Apache started
`requests_per_second`, `bytes_per_second`, `bytes_per_request`	Apache’s own running averages
`cpu_load_ratio`	Apache’s own `CPULoad` value
`connections_total`, `connections_async_writing`, `connections_async_keepalive`, `connections_async_closing`	async connection counts (event and worker MPMs)
`version_info`	presence; the `Server` response header	`version`

scoreboard always adds up to the configured number of worker slots: states are waiting, open_slot, starting, reading, sending, keepalive, dns_lookup, closing, logging, finishing and idle_cleanup.

The monitor page

The panel above the charts reads what the probe stored; opening the page never queries Apache. It shows busy and idle workers, the scoreboard breakdown, and, with ExtendedStatus, the request and byte rates over 24 hours.

Enable Apache’s mod_status

Enable mod_status (it ships with Apache and is usually on already).
```
a2enmod status
```
Add this location to the Apache configuration, restricted to the DumbMonit host (adjust the address).
```
<Location "/server-status">
SetHandler server-status
Require ip 10.0.0.5
</Location>
```
Optional: turn on the request and byte counters.
```
ExtendedStatus On
```
Reload Apache, then open http://apache.lan/server-status?auto from the DumbMonit host.
```
apachectl graceful
```
In DumbMonit, enter the Apache host, for example apache.lan, and the path if it is not /server-status.

Good to know

On Debian and Ubuntu the location goes in a file of its own, elsewhere in the main configuration. DumbMonit adds ?auto itself. Without ExtendedStatus only busy and idle workers and the scoreboard are reported. Apache does not publish its own version in mod_status; DumbMonit reads it from the Server response header instead, which some distributions trim down on purpose.

Vendor documentation: https://httpd.apache.org/docs/2.4/mod/mod_status.html

Credentials

Credential	Fields
No password	Nothing: the status page is filtered so that only DumbMonit reaches it.
Basic auth	The user and password of the block protecting the status page, if any.

Address: a host name or IP, with the port if it is not 80. Options: protocol (HTTP by default), port, status path (/server-status by default, ?auto added automatically), certificate check and request timeout (10 s).