diagnostics: disable nginx reverse proxy buffering on configd streams

[Greelan]

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Describe the problem

The dashboard traffic and CPU widgets and the live firewall log stutter behind a buffering nginx reverse proxy.

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Describe the proposed solution

These event streams follow the same pattern as the live log widget, so adding the same X-Accel-Buffering header as was added for the live log widget in #10086.

The alternative is to do it centrally in ApiControllerBase.php.

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Related issue

N/A

[AdSchellevis]

Maybe its better to merge a header before

core/src/opnsense/mvc/app/controllers/OPNsense/Base/ApiControllerBase.php

Line 230 in 633a313

foreach ($headers as $header) {

Personally I do find their header a bit obscure as we're already asking to not cache this stream with standard headers, in practice other webservers will usually just drop this anyway.

[Greelan]

Right, that was the alternative I mentioned. Wasn't sure you would want Base touched. Anyway, done now.

[AdSchellevis]

in this case it might be better, but is X-Accel-Buffering really connected to a certain type? I would expect streams should never be cached in between..

[Greelan]

I was focused on SSE. I think the only other use is for CSV exports, where buffering may actually help?

[AdSchellevis]

I think all current callers use the same type, but if at some point it seems to make sense to filter these, we can have a look then. For now I would prefer a single strategy and wait for feedback. When there is a valid reason to not do this, we should probably add the tag with a yes and filter on the header itself.

[Greelan]

This is what I was referring to:

core/src/opnsense/mvc/app/controllers/OPNsense/Diagnostics/Api/LogController.php

Lines 82 to 91 in 02b7e4c

	return $this->configdStream(
	'system diag log_stream',
	[0, 0, $searchPhrase, $module, $scope, $severities, $validFrom],
	[
	'Content-Type: text/csv',
	'Content-Disposition: attachment; filename=' . $scope . '.log',
	'Content-Transfer-Encoding: binary',
	'Pragma: no-cache',
	'Expires: 0'
	],

But I can remove the type test if that is still your preference.

[AdSchellevis]

let's remove the test, if someone complains, we'll see

[Greelan]

OK, done.