PIAWARE_MINIMAL: make it clear the map is disabled (#215)

lighttpd: set 'Cache-Control: no-cache' so changes like the map being
disabled are not obscured by the browser cache

rootfs/etc/lighttpd/skyaware.lighttpd.conf

@@ -82,6 +82,8 @@ $HTTP["url"] =~ "^/dump1090-fa/data/.*\.json$" {
   setenv.add-response-header = ( "Access-Control-Allow-Origin" => "*" )
 }
 
+setenv.add-response-header = ( "Cache-Control" => "no-cache" )
+
 # Allows access to the static files that provide the skyaware978 map view,
 # and also to the dynamically-generated json parts that contain aircraft
 # data and are periodically written by the skyaware978 daemon.

rootfs/etc/s6-overlay/scripts/01-piaware

@@ -86,7 +86,11 @@ elif [[ "$UAT_RECEIVER_TYPE" == "rtlsdr" ]]; then
 fi
 
 MLAT_RESULTS_STRING="beast,listen,30105 ext_basestation,listen,30106 "
-if ! chk_enabled "${PIAWARE_MINIMAL}"; then
+
+if [[ -n "$BEASTHOST" ]] && chk_enabled "${PIAWARE_MINIMAL}"; then
+    # make it obvious the map is not available when PIAWARE_MINIMAL is set
+    sed -i -e "s#'/skyaware.*/'#''#g" -e "s/Go to.*SkyAware Map/Map disabled/g" /var/www/html/index.js
+else
     MLAT_RESULTS_STRING+="beast,connect,localhost:30104 "
 fi