use 127.0.0.1 instead of localhost for db host parameter

[Flyingmana]

localhost means connect via socket, which is in some cases not available
or wrong configured or differs from the place php assumes it.

known Downsides: there may be performance impacts, but I never had something noticeable

Reason: It happens regularly that people have connection problems with localhost, which nearly always got resolved by changing to 127.0.0.1

[airbone42]

It's a long way till then, but the advantage of using localhost is that it also maps correctly for ipv6 where ::1 is the equivalent to 127.0.0.1

[Flyingmana]

which is not true for PDO. PDO maps localhost to the default socket configured in php.
Also I dont think any system will completely disable IPv4

[maksek]

Thanks @Flyingmana, seems like there are different opinions. Lets see if there is more comments or opinions. Maybe voting will help. For now we keep it queue.

[danslo]

IPv6 which was already mentioned, so I won't go into that.

I think we should provide a sensible default, which in my eyes is whatever the system/runtime/library decides it to be. If those decide that localhost means a socket instead, it probably has a good reason for that.

I don't think we should design the framework around people that configure their stack incorrectly.

[Marko-M]

👍 for what @danslo wrote. We should use localhost, and envirnoment can then resolve depending on how it's configured.

[maksek]

Hi @Flyingmana,
Resolution: reject, Reason: taking in account comments from @Marko-M, @danslo, @airbone42 and Magento Core team discussion, we agreed to keep localhost.
Thanks and looking forward for more PR.