Hidden listener option tag

[dklimpel]

Description

I have seen an undocumented config option tag / site_tag in

synapse/synapse/app/homeserver.py

Lines 86 to 88 in 9af2be1

	site_tag = listener_config.http_options.tag
	if site_tag is None:
	site_tag = str(port)

• Is it used and only not good documented?
  • It is mentioned in log format in column BBBB
• Or is it old an deprecated?
• Does it make sense to document it in listener documentation?
• And does it have other purposes than replacing the port with the tag in logging?

Origin: #187

[DMRobertson]

Thanks for spotting.

Is it used and only not good documented?

Yes, it's used and poorly documented.

Or is it old an deprecated?

Not old, not deprecated.

Does it make sense to document it in listener documentation?

Yes please!

And does it have other purposes than replacing the port with the tag in logging?

I took a look at the source code: it's only a diagnostic for logging. The option only seems to be used to configure the access logger's name, though I notice that it does get included in structured logging records:

synapse/synapse/logging/context.py

Line 604 in d8cc86e

record.site_tag = request.site_tag