Allow redis to be used over a UNIX socket

[trwnh]

to use a socket, set this in .env:

REDIS_SCHEME=unix
REDIS_PATH=/path/to/redis.sock

Redis socket can be defined in /etc/redis.conf:

port 0    # this disables tcp listening for redis
unixsocket /run/redis/redis.sock
unixsocket 770

add users to redis group to give them access to redis, e.g.

sudo usermod -aG redis {pixelfed,http}