net: refactor find_candidate_nics_on_linux() to use get_interfaces() (#2159)

Much of the filtering logic used in get_interfaces() is duplicated in
find_candidate_nics_on_linux(). Consolidate the two interfaces by
updating find_candidate_nics_on_linux() to use get_interfaces() and
provide boolean toggles to maintain existing behavior.

The following parameters have been added to get_interfaces():
log_filtered_reasons: bool = False
filter_openvswitch_internal: bool = True
filter_vlan: bool = True
filter_without_own_mac: bool = True
filter_zero_mac: bool = True

It may be that these deltas are unwanted or harmless, but the toggles
could be removed independently with more deliberate consideration.
Similarly, logging could be extended if desired for
log_filtered_reasons.

Signed-off-by: Chris Patterson <cpatterson@microsoft.com>

1 files changed, 39 insertions, 29 deletions

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index 46bce184..2a6826b5 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -516,30 +516,20 @@ def find_candidate_nics_on_linux(
     # and ignore interfaces that are definitely disconnected
     connected = []
     possibly_connected = []
-    for interface in get_devicelist():
+    for interface, _, _, _ in get_interfaces(
+        blacklist_drivers=blacklist_drivers,
+        filter_openvswitch_internal=False,
+        filter_slave_if_master_not_bridge_bond_openvswitch=False,
+        filter_vlan=False,
+        filter_without_own_mac=False,
+        filter_zero_mac=False,
+        log_filtered_reasons=True,
+    ):
         if interface == "lo":
             continue
-        driver = device_driver(interface)
-        if driver in blacklist_drivers:
-            LOG.debug(
-                "Ignoring interface with %s driver: %s", driver, interface
-            )
-            continue
-        if not read_sys_net_safe(interface, "address"):
-            LOG.debug("Ignoring interface without mac: %s", interface)
-            continue
         if interface.startswith("veth"):
             LOG.debug("Ignoring veth interface: %s", interface)
             continue
-        if is_bridge(interface):
-            LOG.debug("Ignoring bridge interface: %s", interface)
-            continue
-        if is_bond(interface):
-            LOG.debug("Ignoring bond interface: %s", interface)
-            continue
-        if is_netfailover(interface):
-            LOG.debug("Ignoring failover interface: %s", interface)
-            continue
         carrier = read_sys_net_int(interface, "carrier")
         if carrier:
             connected.append(interface)
@@ -1098,10 +1088,19 @@ def get_interfaces_by_mac_on_linux(blacklist_drivers=None) -> dict:
     return ret
 
 
-def get_interfaces(blacklist_drivers=None) -> list:
+def get_interfaces(
+    blacklist_drivers=None,
+    filter_openvswitch_internal: bool = True,
+    filter_slave_if_master_not_bridge_bond_openvswitch: bool = True,
+    filter_vlan: bool = True,
+    filter_without_own_mac: bool = True,
+    filter_zero_mac: bool = True,
+    log_filtered_reasons: bool = False,
+) -> list:
     """Return list of interface tuples (name, mac, driver, device_id)
 
     Bridges and any devices that have a 'stolen' mac are excluded."""
+    filtered_logger = LOG.debug if log_filtered_reasons else lambda *args: None
     ret = []
     if blacklist_drivers is None:
         blacklist_drivers = []
@@ -1109,33 +1108,44 @@ def get_interfaces(blacklist_drivers=None) -> list:
     # 16 somewhat arbitrarily chosen.  Normally a mac is 6 '00:' tokens.
     zero_mac = ":".join(("00",) * 16)
     for name in devs:
-        if not interface_has_own_mac(name):
+        if filter_without_own_mac and not interface_has_own_mac(name):
             continue
         if is_bridge(name):
+            filtered_logger("Ignoring bridge interface: %s", name)
             continue
-        if is_vlan(name):
+        if filter_vlan and is_vlan(name):
             continue
         if is_bond(name):
+            filtered_logger("Ignoring bond interface: %s", name)
+            continue
+        if (
+            filter_slave_if_master_not_bridge_bond_openvswitch
+            and get_master(name) is not None
+            and not master_is_bridge_or_bond(name)
+            and not master_is_openvswitch(name)
+        ):
             continue
-        if get_master(name) is not None:
-            if not master_is_bridge_or_bond(
-                name
-            ) and not master_is_openvswitch(name):
-                continue
         if is_netfailover(name):
+            filtered_logger("Ignoring failover interface: %s", name)
             continue
         mac = get_interface_mac(name)
         # some devices may not have a mac (tun0)
         if not mac:
+            filtered_logger("Ignoring interface without mac: %s", name)
             continue
         # skip nics that have no mac (00:00....)
-        if name != "lo" and mac == zero_mac[: len(mac)]:
+        if filter_zero_mac and name != "lo" and mac == zero_mac[: len(mac)]:
             continue
-        if is_openvswitch_internal_interface(name):
+        if filter_openvswitch_internal and is_openvswitch_internal_interface(
+            name
+        ):
             continue
         # skip nics that have drivers blacklisted
         driver = device_driver(name)
         if driver in blacklist_drivers:
+            filtered_logger(
+                "Ignoring interface with %s driver: %s", driver, name
+            )
             continue
         ret.append((name, mac, driver, device_devid(name)))
     return ret