Nginx – Sharing unix socket via docker volume – permission denied

I try to share my php5-fpm socket via a volume with my nginx webserver. Fpm and nginx are running in different containers and I want to get them working via a shared volume where I place the socket file from fpm.

2014/04/13 10:53:35 [crit] 33#0: *1 connect() to unix:/container/fpm/run/php5-fpm.sock failed (13: Permission denied) while connecting to upstream, client: 192.168.8.2, server: docker.dev, request: "GET /test.php HTTP/1.1", upstream: "fastcgi://unix:/container/fpm/run/php5-fpm.sock:", host: "docker.dev"

I already tried setting permissions to 777 and changing the group of php5-fpm.socket to www-data.

Dockerfile of fpm container

FROM ubuntu:13.10

RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get install -y php5-cli php5-common
RUN apt-get install -y php5-fpm php5-cgi

ADD ./php-fpm.conf /etc/php5/fpm/php-fpm.conf
ADD ./pool.d/www.conf /etc/php5/fpm/pool.d/www.conf
ADD ./php.ini /etc/php5/fpm/php.ini

CMD ["/usr/sbin/php5-fpm"]

Dockerfile of nginx container

FROM ubuntu:13.10

RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get install -y nginx

ADD ./test.php /var/test/test.php
ADD ./test.html /var/test/test.html
ADD ./nginx.conf /etc/nginx/nginx.conf
ADD ./site /etc/nginx/sites-enabled/test

EXPOSE 80

CMD ["/usr/sbin/nginx"]

I can access the test.html but when accessing test.php I get 502 Bad Gateway.

Is there anything else I have to care about permissions when sharing stuff via volumes?