Unix file socket not working

I'm having trouble with red:connect("unix:/tmp/redis.sock"). It does not appear to be working.

Full code snippet

local ok, err = red:connect("unix:/tmp/redis.sock")
if not ok then
    ngx.log(ngx.ERR, "failed to connect to redis: ", err)
    ngx.print("no redis")
    return
end

In the error log

2016/01/28 13:55:53 [crit] 30531#0: *1 connect() to unix:/tmp/redis.sock failed (2: No such file or directory), client: 10.0.2.2, server: _, request: "POST /lee/models/HelloWorld/ HTTP/1.1", host: "127.0.0.1:12080"

and the socket file itself does exist and is 0777

[root@localhost ~]# stat /tmp/redis.sock
  File: ‘/tmp/redis.sock’
  Size: 0           Blocks: 0          IO Block: 4096   socket
Device: fd01h/64769d    Inode: 263869      Links: 1
Access: (0777/srwxrwxrwx)  Uid: (    0/    root)   Gid: (    0/    root)
Context: unconfined_u:object_r:user_tmp_t:s0
Access: 2016-01-28 13:54:54.289000000 -0500
Modify: 2016-01-28 13:54:54.289000000 -0500
Change: 2016-01-28 13:54:54.289000000 -0500
 Birth: -

Start by locating the implementation of red:connect and its Unix-socket handling, then reproduce the reported connection failure with the socket path and error log shown. Determine whether the behavior is a client defect or an environment issue; done means the root cause is established and, if a defect is confirmed, the behavior is corrected with coverage for this connection form.