trying to improve error handling inside get_all_by_host_and_network

capsulflask/shell_scripts/virsh-list.sh

···
 printf  '['
 delimiter=""
 virsh list --all | tail -n +3 | while read -r line; do
-  capsul_id="$(echo "$line" | awk '{ print $2 }')"
-  capsul_state="$(echo "$line" | sed -E 's/^ *[0-9-]+ +[^ ]+ +//')"
-  printf '%s\n  {"id":"%s", "state":"%s"}' "$delimiter" "$capsul_id" "$capsul_state"
-  delimiter=","
+  if [ "$line" != "" ]; then
+    capsul_id="$(echo "$line" | awk '{ print $2 }')"
+    capsul_state="$(echo "$line" | sed -E 's/^ *[0-9-]+ +[^ ]+ +//')"
+    printf '%s\n  {"id":"%s", "state":"%s"}' "$delimiter" "$capsul_id" "$capsul_state"
+    delimiter=","
+  fi
 done
 printf '\n]\n'

capsulflask/shell_scripts/virsh-net-list.sh

···
 printf  '['
 delimiter=""
 virsh net-list --all | tail -n +3 | awk '{ print $1 }' | while read -r network_name; do
-  virtual_bridge_name="$(virsh net-info "$network_name" | grep -E  '^Bridge:' | awk '{ print $2 }')"
-  capsul_state="$(echo "$line" | sed -E 's/^ *[0-9-]+ +[^ ]+ +//')"
-  printf '%s\n  {"name":"%s", "virtual_bridge_name":"%s"}' "$delimiter" "$network_name" "$virtual_bridge_name"
-  delimiter=","
+  if [ "$line" != "" ]; then
+    virtual_bridge_name="$(virsh net-info "$network_name" | grep -E  '^Bridge:' | awk '{ print $2 }')"
+    capsul_state="$(echo "$line" | sed -E 's/^ *[0-9-]+ +[^ ]+ +//')"
+    printf '%s\n  {"name":"%s", "virtual_bridge_name":"%s"}' "$delimiter" "$network_name" "$virtual_bridge_name"
+    delimiter=","
+  fi
 done
 printf '\n]\n'
 

capsulflask/spoke_model.py

···
 
     vm_list_process = run([join(current_app.root_path, 'shell_scripts/virsh-list.sh')], capture_output=True)
     self.validate_completed_process(vm_list_process)
-    list_of_vms = json.loads(vm_list_process.stdout.decode("utf-8"))
+    vms_json_string = vm_list_process.stdout.decode("utf-8")
+    current_app.logger.info(f"vms_json_string: {vms_json_string}")
+    list_of_vms = json.loads(vms_json_string)
 
     current_app.logger.info(f"list_of_vms: {json.dumps(list_of_vms)}")
 
···
 
     net_list_process = run([join(current_app.root_path, 'shell_scripts/virsh-net-list.sh')], capture_output=True)
     self.validate_completed_process(net_list_process)
-    list_of_networks = json.loads(net_list_process.stdout.decode("utf-8"))
+    net_list_json_string = net_list_process.stdout.decode("utf-8")
+    current_app.logger.info(f"net_list_json_string: {net_list_json_string}")
+    list_of_networks = json.loads(net_list_json_string)
 
     current_app.logger.info(f"list_of_networks: {json.dumps(list_of_networks)}")
 
···
     vm_id_by_mac = dict()
     for network in list_of_networks:
 
-      with open(f"{current_app.config['LIBVIRT_DNSMASQ_PATH']}/{network['virtual_bridge_name']}.macs", mode='r') as macs_json_file:
-        vms_with_macs = json.load(macs_json_file)
+      macs_json_filename = f"{current_app.config['LIBVIRT_DNSMASQ_PATH']}/{network['virtual_bridge_name']}.macs"
+      with open(macs_json_filename, mode='r') as macs_json_file:
+        vms_with_macs = []
+        try:
+          vms_with_macs = json.load(macs_json_file)
+        except:
+          raise Exception(f"failed to parse the JSON file '{macs_json_filename}'")
+
         for vm in vms_with_macs:
           for mac in vm['macs']:
             if mac not in vm_id_by_mac:
···
                
             vms_by_id[vm['domain']]['macs'][mac] = True
       
-      with open(f"{current_app.config['LIBVIRT_DNSMASQ_PATH']}/{network['virtual_bridge_name']}.status", mode='r') as status_json_file:
-        statuses = json.load(status_json_file)
+      status_json_filename = f"{current_app.config['LIBVIRT_DNSMASQ_PATH']}/{network['virtual_bridge_name']}.status"
+      with open(status_json_filename, mode='r') as status_json_file:
+        statuses = []
+        try:
+          statuses = json.load(status_json_file)
+        except:
+          raise Exception(f"failed to parse the JSON file '{status_json_filename}'")
+        
         for status in statuses:
           if status['mac-address'] in vm_id_by_mac:
             vm_id = vm_id_by_mac[status['mac-address']]