The Dockerfile now even works.

Dockerfile

@@ -1,4 +1,15 @@
+# Spreed WebRTC server.
+#
+# To execute it install docker and then run 'sudo docker build .'
+#
 FROM ubuntu:trusty
+MAINTAINER Simon Eisenmann <simon@struktur.de>
+
+# Set locale.
+RUN locale-gen --no-purge en_US.UTF-8
+ENV LC_ALL en_US.UTF-8
+
+ENV DEBIAN_FRONTEND noninteractive
 
 # Base system
 RUN apt-get update -q
@@ -14,11 +25,9 @@ RUN ./configure
 RUN make pristine && make
 
 # Create default config file.
-RUN cp -v /srv/spreed-webrtc/server.conf.in /srv/spreed-webrtc/server.conf
-RUN sed -i 's|listen = 127.0.0.1:8080|listen = 0.0.0.0:8080|' /srv/spreed-webrtc/server.conf
-RUN sed -i 's|sessionSecret = .*|sessionSecret = `openssl rand -hex 32`|' /srv/spreed-webrtc/server.conf
-RUN sed -i 's|encryptionSecret = .*|encryptionSecret = `openssl rand -hex 16`|' /srv/spreed-webrtc/server.conf
-RUN sed -i 's|;root = .*|root = /srv/spreed-webrtc|' /srv/spreed-webrtc/server.conf
+RUN cp -v /srv/spreed-webrtc/server.conf.in /srv/spreed-webrtc/server.conf && \
+	sed -i 's|listen = 127.0.0.1:8080|listen = 0.0.0.0:8080|' /srv/spreed-webrtc/server.conf && \
+	sed -i 's|;root = .*|root = /srv/spreed-webrtc|' /srv/spreed-webrtc/server.conf
 
 # Allow to mount.
 VOLUME /srv/spreed-webrtc