From b9f9e7d1b05a4c6ef44d3c47bce46b8c63cb4a58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Thu, 19 Mar 2020 19:07:12 +0100
Subject: [PATCH] Handle libvirt errors and logging

---
 lxc_net/libvirt_error.py | 105 +++++++++++++++++++++++++++++++++++++++
 spawn_network.py         |   6 ++-
 2 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 lxc_net/libvirt_error.py

diff --git a/lxc_net/libvirt_error.py b/lxc_net/libvirt_error.py
new file mode 100644
index 0000000..f185288
--- /dev/null
+++ b/lxc_net/libvirt_error.py
@@ -0,0 +1,105 @@
+from collections import namedtuple
+import libvirt
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class LibvirtErrorCode:
+    reverse_errors = {
+        getattr(libvirt, err_name): err_name
+        for err_name in filter(lambda x: x.startswith("VIR_ERR_"), libvirt.__dir__())
+    }
+
+    def __init__(self, code):
+        self.code = code
+        self.err = self.reverse_errors.get(code, None)
+
+    def __repr__(self):
+        return "{}".format(self.code)
+
+    def __str__(self):
+        return "{} [{}]".format(self.err, self.code)
+
+    def __eq__(self, val):
+        return self.code == val
+
+
+class LibvirtErrorDomain:
+    reverse_domains = {
+        getattr(libvirt, err_name): err_name
+        for err_name in filter(lambda x: x.startswith("VIR_DOMAIN_"), libvirt.__dir__())
+    }
+
+    def __init__(self, code):
+        self.code = code
+        self.domain = self.reverse_domains.get(code, None)
+
+    def __repr__(self):
+        return "{}".format(self.code)
+
+    def __str__(self):
+        return "{} [{}]".format(self.domain, self.code)
+
+    def __eq__(self, val):
+        return self.code == val
+
+
+class LibvirtError:
+    params = (
+        "code",
+        "domain",
+        "message",
+        "level",
+        "str1",
+        "str2",
+        "str3",
+        "int1",
+        "int2",
+    )
+
+    def __init__(self, code, domain, message, level, str1, str2, str3, int1, int2):
+        self.code = LibvirtErrorCode(code)
+        self.domain = LibvirtErrorDomain(domain)
+        self.message = message
+        self.level = level
+        self.str1 = str1
+        self.str2 = str2
+        self.str3 = str3
+        self.int1 = int1
+        self.int2 = int2
+
+    def __repr__(self):
+        out = "{}(".format(self.__class__.__name__)
+        for param in self.__class__.params:
+            out += "{}={}, ".format(param, getattr(self, param))
+        out += ")"
+        return out
+
+    def __str__(self):
+        return "Libvirt error {}, domain {}. {}".format(
+            self.code, self.domain, self.message
+        )
+
+    @property
+    def loglevel(self):
+        levelmap = {
+            0: logging.INFO,
+            1: logging.WARNING,
+            2: logging.ERROR,
+        }
+
+        return levelmap.get(self.level, logging.CRITICAL)
+
+
+def libvirt_error_handler(_, raw_error):
+    """ Called upon libvirt error """
+
+    error = LibvirtError(*raw_error)
+    loglevel = error.loglevel
+
+    if error.code == libvirt.VIR_ERR_NO_DOMAIN:
+        loglevel = logging.DEBUG
+
+    logger.log(loglevel, str(error))
diff --git a/spawn_network.py b/spawn_network.py
index 2f1775a..f169280 100755
--- a/spawn_network.py
+++ b/spawn_network.py
@@ -1,9 +1,10 @@
 #!/usr/bin/env python3
 
-from lxc_net import parse_network
+from lxc_net import parse_network, libvirt_error
 import signal
 import libvirt
 import argparse
+import logging
 
 
 def parse_args():
@@ -28,6 +29,9 @@ def main():
 
     signal.signal(signal.SIGINT, handle_sigint)
 
+    logging.basicConfig(level=logging.WARNING)
+    libvirt.registerErrorHandler(libvirt_error.libvirt_error_handler, None)
+
     conn = libvirt.open("lxc:///")
 
     topology = parse_network.YamlTopology(args.topology, conn)