PHP and Redis Unix Socket Semantics

[Jordan Geoghegan]

Hello,

I was recently doing a Roundcube install and wanted to use Redis over a 
unix socket.
I configured Redis to put a socket in /var/www/run/redis/redis.sock with 
770 permissions.
I then added the www user to the _redis group and confirmed www users 
access to socket via "doas -u www redis-cli -s 
/var/www/run/redis/redis.sock ping"

I then found myself getting a permission issue and php/roundcube unable 
to connect to the socket. Setting the socket to 777 makes everything work.

I'm at a loss as to why this doesn't work. According to ps all php 
processes are running as user www.
My _rspamd user is part of the _redis group and is perfectly able to 
write to the socket when _redis:_redis 770 permissions are set, so I 
assumed it would be same same for www user.

I feel like I must be missing something obvious here, so hoping the fine 
folks here can point me in the right direction.

Regards,

Jordan