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File streaming does not reset gzip headers anymore
Closed, ResolvedPublic

Description

Steps:

  1. Open a private browser window
  2. Go to https://deployment.wikimedia.beta.wmflabs.org/wiki/Special:UserLogin
  3. See that no Captcha is displayed; request triggers a 503 error (Request via deployment-cache-text04 deployment-cache-text04, Varnish XID 1270177689)

This was brought up on en.wp's VP, effectively blocking not-yet-registered users from trying the new wikitext editor.

It seems to be not the first time this problem appears.

Event Timeline

Aklapper created this task.Sep 28 2016, 3:11 PM

Looking at varnishlog, it successfully gets to deployment-mediawiki04, but then this happens:

13 FetchError   c Invalid Gzip data: incorrect header check
13 Gzip         c u F - 2 0 0 0 0
13 VCL_call     c error deliver
13 VCL_call     c deliver deliver
13 TxProtocol   c HTTP/1.1
13 TxStatus     c 503
13 TxResponse   c Service Unavailable

It seems that Apache claims it's sending gzipped content (with Content-Encoding: gzip), but it then sends just a plain PNG file, no gzip encoding

The obResetFunc property of the result of FileBackendGroup::singleton()->get( 'global-multiwrite' ) points to the backend's resetOutputBuffer function, instead of wfResetOutputBuffers which would handle this

Restricted Application added projects: Multimedia, Commons. · View Herald TranscriptSep 28 2016, 4:14 PM
Restricted Application added subscribers: Poyekhali, Matanya. · View Herald TranscriptSep 28 2016, 4:14 PM
AlexMonk-WMF renamed this task from Cannot create account on deployment.wikimedia.beta.wmflabs.org: No Captcha due to 503 error to File streaming does not reset gzip headers anymore.Sep 28 2016, 4:16 PM
AlexMonk-WMF added a subscriber: Krinkle.

Change 313287 had a related patch set uploaded (by Aaron Schulz):
Fix use of bogus $params var in FileBackend::__construct()

https://gerrit.wikimedia.org/r/313287

Change 313287 merged by jenkins-bot:
Fix use of bogus $params var in FileBackend::__construct()

https://gerrit.wikimedia.org/r/313287

Change 313323 had a related patch set uploaded (by Aaron Schulz):
Set the stream and buffer reset methods for the default backend

https://gerrit.wikimedia.org/r/313323

Change 313323 merged by jenkins-bot:
Set the stream and buffer reset methods for the default backend

https://gerrit.wikimedia.org/r/313323

The patch is merged and deployed in beta, and the backend returned by FileBackendGroup::singleton()->get( 'global-multiwrite' ) has [obResetFunc":protected] => "wfResetOutputBuffers", but it's still sending the Content-Encoding header without gzipping the file

greg added a subscriber: greg.Sep 28 2016, 11:06 PM

The problem here is 'template' handling, <<$config['backends'][$index] += $this->config( $beConfig['template'] );>> does not set all the things get() does.

Change 313340 had a related patch set uploaded (by Aaron Schulz):
Make multi-write backend "template" config work as expected

https://gerrit.wikimedia.org/r/313340

Change 313340 merged by jenkins-bot:
Make multi-write backend "template" config work as expected

https://gerrit.wikimedia.org/r/313340

aaron closed this task as Resolved.Sep 30 2016, 12:02 AM