novnc snap now creates services specified by snap set config settings. Switched to forking daemon type to handle multiple novnc services at a time

snap/snapcraft.yaml

@@ -17,6 +17,8 @@ parts:
             - websockify
             - bash
             - jq
+            - python-numpy
+            - python3-numpy
 
 hooks:
     install:
@@ -30,5 +32,5 @@ apps:
         plugs: [network, network-bind]
     novncsvc:
         command: utils/svc_wrapper.sh
-        daemon: simple
+        daemon: forking
         plugs: [network, network-bind]

utils/svc_wrapper.sh

@@ -1,19 +1,29 @@
 #!/bin/bash
 
-echo "snactp get services is: $(snapctl get services)"
-
-#for service in $(snapctl get services | cut -f1 -d' ' |cut -f2 -d".") # the cut calls get only the first column and then change 'service.n6801' to 'n6801'
-snapctl get services | jq -c '.[]' | while read service; do
-    listen_port="$(echo $service | jq '.listen')"
-    vnc_host_port="$(echo $service | jq '.vnc')"
-
-    # check for valid values
+# `snapctl get services` returns a JSON array, example:
+#{
+#"n6801": {
+#   "listen": 6801,
+#   "vnc": "localhost:5901"
+#},
+#"n6802": {
+#    "listen": 6802,
+#   "vnc": "localhost:5902"
+#}
+#}
+snapctl get services | jq -c '.[]' | while read service; do # for each service the user sepcified..
+    # get the important data for the service (listen port, VNC host:port)
+    listen_port="$(echo $service | jq --raw-output '.listen')"
+    vnc_host_port="$(echo $service | jq --raw-output '.vnc')" # --raw-output removes any quotation marks from the output
+    
+    # check whether those values are valid
     expr "$listen_port" : '^[0-9]\+$' > /dev/null
     listen_port_valid=$?
     if [ ! $listen_port_valid ] || [ -z "$vnc_host_port" ]; then
-        # invalid values mean the service is disabled, do nothing
+        # invalid values mean the service is disabled, do nothing except for printing a message (logged in /var/log/system or systemd journal)
         echo "novnc: not starting service ${service} with listen_port ${listen_port} and vnc_host_port ${vnc_host_port}"
     else
-        $SNAP/utils/launch.sh --listen $listen_port --vnc $vnc_host_port
+        # start (and fork with '&') the service using the specified listen port and VNC host:port
+        $SNAP/utils/launch.sh --listen $listen_port --vnc $vnc_host_port &
     fi
 done