Merge branch '13-net-dev' into 'master'

Resolve #13 "Net dev"

See merge request ix.ai/smtp!15

README.md

@@ -23,6 +23,8 @@ To disable IPV6 you can set the `DISABLE_IPV6` environment variable to any value
 
 The container accepts `OTHER_HOSTNAMES` environment variable which will set the list of domains for which this machine should consider itself the final destination.
 
+The container accepts `NET_DEV` environment variable to override the default `eth0` interface for retrieving the IP address for relay networks.
+
 ## Below are scenarios for using this container
 
 ### As SMTP Server

entrypoint.sh

@@ -55,7 +55,7 @@ fi
 opts=(
 	dc_local_interfaces "[${BIND_IP:-0.0.0.0}]:${PORT:-25} ; [${BIND_IP6:-::0}]:${PORT:-25}"
 	dc_other_hostnames "${OTHER_HOSTNAMES}"
-	dc_relay_nets "$(ip addr show dev eth0 | awk '$1 == "inet" { print $2 }' | xargs | sed 's/ /:/g')${RELAY_NETWORKS}"
+	dc_relay_nets "$(ip addr show dev "${NET_DEV:-eth0}" | awk '$1 == "inet" { print $2 }' | xargs | sed 's/ /:/g')${RELAY_NETWORKS}"
 )
 
 if [ "$DISABLE_IPV6" ]; then