Add BIND_INTERFACE env var

Allows setting the `bind-interface` config option in fr24feed.ini
to allow access from non-private IP addresses. Can be set to
`0.0.0.0` to allow access from any IP address (warning, may be
insecure). If env var is not set (default), the config option
will not be added to the config file, which is a secure default.

Fixes sdr-enthusiasts#58

README.md

@@ -132,6 +132,7 @@ There are a series of available environment variables:
 | `BEASTHOST` | Required. IP/Hostname of a Mode-S/BEAST provider (dump1090) | `readsb` |
 | `BEASTPORT` | Optional. TCP port number of Mode-S/BEAST provider (dump1090) | `30005` |
 | `FR24KEY` | Required. Flightradar24 Sharing Key | |
+| `BIND_INTERFACE` | Optional. Set a bind interface such as `0.0.0.0` to allow access from non-private IP addresses | _none_ |
 | `TZ` | Your local timezone (optional) | `GMT` |
 | `VERBOSE_LOGGING` | Set to `true` to enable verbose logging (optional) | `false` |
 

rootfs/etc/cont-init.d/01-fr24feed

@@ -34,6 +34,9 @@ fi
  echo logpath="/var/log"
  echo mlat="no"
  echo mlat-without-gps="no"
+ if [ -n "${BIND_INTERFACE}" ]; then
+ echo bind-interface="${BIND_INTERFACE}"
+ fi
 } > /etc/fr24feed.ini
 
 # prepare directories (from /usr/lib/fr24/create_missing_directories.sh)