network_traffic: allow to hide down interfaces

Interfaces which are down can be hidden or formatted differently.

The following options are added:
hide_down - whether to not display a interface which is down
format_down - format string if the interface is down (unless hide_down is set)

i3pystatus/network_traffic.py

@@ -21,12 +21,16 @@ class NetworkTraffic(IntervalModule):
     interval = 1
     settings = (
         ("format", "format string"),
+        ("format_down", "format string if the interface is down (unless hide_down is set)"),
+        ("hide_down", "whether to not display a interface which is down"),
         ("interface", "network interface"),
         ("divisor", "divide all byte values by this value"),
         ("round_size", "defines number of digits in round"),
     )
 
     format = "{interface} \u2197{bytes_sent}kB/s \u2198{bytes_recv}kB/s"
+    format_down = "{interface} \u2013"
+    hide_down = True
     interface = "eth0"
     divisor = 1024
     round_size = None
@@ -36,7 +40,8 @@ class NetworkTraffic(IntervalModule):
 
     def update_counters(self):
         self.pnic_before = self.pnic
-        self.pnic = psutil.net_io_counters(pernic=True)[self.interface]
+        counters = psutil.net_io_counters(pernic=True)
+        self.pnic = counters[self.interface] if self.interface in counters else None
 
     def get_bytes_sent(self):
         return (self.pnic.bytes_sent - self.pnic_before.bytes_sent) / self.divisor
@@ -50,8 +55,18 @@ class NetworkTraffic(IntervalModule):
     def get_packets_received(self):
         return self.pnic.packets_recv - self.pnic_before.packets_recv
 
+    def sysfs_interface_up(self):
+        try:
+            sysfs = "/sys/class/net/{}/operstate".format(self.interface)
+            with open(sysfs) as operstate:
+                status = operstate.read().strip()
+            return status == "up" or status == "unknown"
+        except FileNotFoundError:
+            return False
+
     def run(self):
         self.update_counters()
+        if self.sysfs_interface_up():
             if not self.pnic_before:
                 return
             cdict = {
@@ -66,3 +81,14 @@ class NetworkTraffic(IntervalModule):
                 "full_text": self.format.format(**cdict),
                 "instance": self.interface,
             }
+        elif self.hide_down:
+            self.output = None
+            return
+        else:
+            cdict = {
+                "interface": self.interface,
+            }
+            self.output = {
+                "full_text": self.format_down.format(**cdict),
+                "instance": self.interface,
+            }