[Bug 1674733] Re: php_network_getaddresses since last update

[Joern Heissler]

I restarted php on affected servers, problem didn't come back yet.
What I saw in strace / tcpdump is a dns request with rrtype 0x5100 in the question.

There have been problems with libc6 updates before and there is this
debconf thingy "Services that need to be restarted". This indicates a
known problem with libc6 updates. php-fpm should be added to this list
of services...

I don't fully understand how exactly the bug "works". My working theory goes like this:
php-fpm master process has lots of shared libs mmaped into memory. Those are not affected by a libc6 upgrade that changes libs on the file system.
When php-fpm forks a worker process, it inherits all the maps.
But the worker process does some actual work and loads (diff /proc/{$master,$worker}/maps) /lib/x86_64-linux-gnu/libnss_dns-2.23.so which is the *new* version and not ABI compatible with the already loaded libc6.
If my theory holds, restarting the affected process will indeed fix the issue.

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https://bugs.launchpad.net/bugs/1674733

Title:
  php_network_getaddresses since last update

Status in glibc package in Ubuntu:
  Confirmed

Bug description:
  Hello,

  Since last update :

  2017-03-21 03:42:53,570 INFO Packages that will be upgraded: libc-bin
  libc-dev-bin libc6 libc6-dev libfreetype6 libfreetype6-dev locales
  multiarch-support

  
  We get a lot of these errors on our production and development environment (PHP Application on Codeigniter) on Ubuntu 14.04 on AWS EC2 :

  
  php_network_getaddresses: getaddrinfo failed: Name or service not known ubuntu


  Apparently we are not alone today :

  http://stackoverflow.com/questions/42926075/pdoexception-
  sqlstatehy000-2002-php-network-getaddresses-getaddrinfo-faile

  http://stackoverflow.com/questions/42925765/pdo-exception-php-network-
  getaddresses-getaddrinfo-failed-after-changing-dns

  http://serverfault.com/questions/839659/php-throwing-server-errors-
  after-ubuntu-ran-an-unattended-upgrades-session-any

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