From 0e1c6f56124e1012baddcb04406b590be08e5eb8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Herv=C3=A9=20Beraud?= Date: Thu, 16 Apr 2020 19:29:09 +0200 Subject: [PATCH] [doc] tell to prefix ipv6 hosts with inet6 Some environments with ipv6 used to connect with memcached servers faced issues by omitting to prefix the host with the address family to use. Indeed libraries like python-memcached waiting for a prefix to initialize the socket with the right address family. If the prefix isn't given and that the host refer or bind an ipv6 then the socket is initialized with an address family which correspond to an IPv4 and the connection doesn't work properly. Openstack's puppet libraries already fixed that by introducing new feature to automatically prefix the address if needed [1][2]. Anyway it could be worth to add more documentation on oslo.cache to give more information to customers and avoid similar issues. These changes aim to provide this documentation. [1] https://review.opendev.org/#/q/status:merged+branch:master+topic:memcached-inet6-prefix [2] https://review.opendev.org/#/c/661136/ Change-Id: I5e0b4818300348efe4625500792d9161281ed45a --- oslo_cache/_opts.py | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/oslo_cache/_opts.py b/oslo_cache/_opts.py index 8fc3ce32..d3ec89a1 100644 --- a/oslo_cache/_opts.py +++ b/oslo_cache/_opts.py @@ -74,9 +74,18 @@ FILE_OPTIONS = { 'keys/values. Typically this should be left set ' 'to false.'), cfg.ListOpt('memcache_servers', default=['localhost:11211'], - help='Memcache servers in the format of "host:port".' - ' (dogpile.cache.memcached and oslo_cache.memcache_pool' - ' backends only).'), + help='Memcache servers in the format of "host:port". ' + '(dogpile.cache.memcached and ' + 'oslo_cache.memcache_pool backends only). ' + 'If a given host refer to an IPv6 or a given domain ' + 'refer to IPv6 then you should prefix the given ' + 'address with the address family (``inet6``) ' + '(e.g ``inet6[::1]:11211``, ' + '``inet6:[fd12:3456:789a:1::1]:11211``, ' + '``inet6:[controller-0.internalapi]:11211``). ' + 'If the address family is not given then default ' + 'address family used will be ``inet`` which ' + 'correspond to IPv4'), cfg.IntOpt('memcache_dead_retry', default=5 * 60, help='Number of seconds memcached server is considered dead'