[Bug 1740114] Re: apt's IPv4 fallback in case of a malfunctioning IPv6 connection works horribly

[Julian Andres Klode]

*** This bug is a duplicate of bug 1308200 ***
    https://bugs.launchpad.net/bugs/1308200

The solution is extremely complicated. It requires a short (300ms)
timeout when falling back from IPv6 to IPv4 and then waiting on _both_.
And then properly reporting errors, so it reports failures for the
correct IP addresses.

I basically had a working prototype in July, but I had to abandon it,
because it did not pass CI. I think its error reporting also was fairly
shaky.

Re 16.04, I don't think we'll see a fix there. The changes are fairly
complex, and it only affects a tiny minority of users (*), and there is
a much easier workaround to apply. Also, this not only affects APT if
your libc is configured to prefer IPv6 on a system without real IPv6
connectivity - some apps just try the first address (IPv6 then), they
will hard-fail quickly.

(*) If someone ever can explain to me what causes this, please do so.
This should not happen. If you have a globally routable IPv6 address and
just drop the IPv6 traffic somewhere down the route, your network is
broken IMO. Don't expect everyone to add workarounds for that.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to apt in Ubuntu.
https://bugs.launchpad.net/bugs/1740114

Title:
  apt's IPv4 fallback in case of a malfunctioning IPv6 connection works
  horribly

Status in apt package in Ubuntu:
  Opinion

Bug description:
  I kindly request that Ubuntu developers stop drinking so much Kool-Aid
  and realize not everyone in this world has a working IPv6 connection
  and an IPv4 fallback must be used in case an IPv6 request takes too
  much time:

  # time apt-get update
  Hit:1 http://de.archive.ubuntu.com/ubuntu xenial InRelease                                                                                                   
  Hit:2 http://de.archive.ubuntu.com/ubuntu xenial-updates InRelease                                                                                           
  Hit:3 http://de.archive.ubuntu.com/ubuntu xenial-backports InRelease                                                                                         
  0% [Connecting to security.ubuntu.com (2001:67c:1560:8001::11)]^C                        

  real	6m10.351s
  user	0m0.056s
  sys	0m0.020s

  What the fuck??? My server doesn't have a working IPv6 connection. The
  apt-get update command apparently never completes. Could there be a
  sane timeout before apt switches to IPv4?

  Why the Internet is full of requests how to disable IPv6 support in
  apt when it takes a few seconds to fix this problem in the first
  place?

  Why the fuck there are such crucial bugs in the first place? Could you
  for fuck's sake make your software usable and bugs-free before trying
  to add a ton of barely working new shiny features?

  Of course, there's this nice thread

  https://unix.stackexchange.com/questions/9940/convince-apt-get-not-to-
  use-ipv6-method

  which fixes this issue, but why the fuck am I supposed to start
  googling from the get go after installing a brand new release of
  Ubuntu

  lsb_release -a
  No LSB modules are available.
  Distributor ID:	Ubuntu
  Description:	Ubuntu 16.04.2 LTS
  Release:	16.04
  Codename:	xenial

  Also why the fuck are you sending a password reset URL which uses
  plain HTTP? Are you fucking insane?

  What the fuck is this shit?

  http://login.launchpad.net/token/xxxxxxxxxxxxxxxxxxxxxxxxx/+resetpassword/example@example.com

  What the fuck is wrong with you people?

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1740114/+subscriptions