Use environment variable to configure the interfaces of a Dante server

The internal and external keywords in the server configuration are used
to specify the network interface (IP address) that the Dante server
should bind to. Because docker-compose allows a container to join more
than one network (by adding multiple entries under the top level
networks key to a docker-compose file), the default server
configuration (danted.conf) shall be updated in accordance with the
settings in the docker-compose file.

The user can pass the setting of a docker-compose file to containers by
adding environment variables in the docker-compose file. After the
container gets created, the danted.sh script uses the input environment
variables to overwrite the default value of internal and external
interfaces before starting the Dante server.

environment:
    - danted_internal=eth1
    - danted_external=eth1
    - danted_auth_internal=eth1
    - danted_auth_external=eth1

Change-Id: I7c65cdd136ba5dac387bee5e22e1f4335e960101
Reviewed-by: Edward Welbourne <[email protected]>
Reviewed-by: Jędrzej Nowacki <[email protected]>

tests/testserver/danted/danted.sh

@@ -39,6 +39,25 @@ useradd -d /dev/null -s /bin/false qsockstest; echo "qsockstest:$PASS" | chpassw
 # install configurations and test data
 cp $TESTDATA/danted{,-authenticating}.conf /etc/
 
+# Use the input environment variables to overwrite the default value of internal interfaces.
+if [ "$danted_internal" -a "$danted_internal" != eth0 ]
+then sed -i "s,internal: eth0 port = 1080,internal: $danted_internal port = 1080," /etc/danted.conf
+fi
+
+if [ "$danted_auth_internal" -a "$danted_auth_internal" != eth0 ]
+then sed -i "s,internal: eth0 port = 1081,internal: $danted_auth_internal port = 1081," \
+     /etc/danted-authenticating.conf
+fi
+
+# Use the input environment variables to overwrite the default value of external interfaces.
+if [ "$danted_external" -a "$danted_external" != eth0 ]
+then sed -i "s,external: eth0,external: $danted_external," /etc/danted.conf
+fi
+
+if [ "$danted_auth_external" -a "$danted_auth_external" != eth0 ]
+then sed -i "s,external: eth0,external: $danted_auth_external," /etc/danted-authenticating.conf
+fi
+
 # enable service with installed configurations
 service danted start
 service danted-authenticating start