DataSourceEc2: use metadata's NIC ordering to determine route-metrics (#342)

We want to set route-metrics such that NICs are configured with the priority that they are given in the network metadata that we receive from the IMDS.  (This switches away from using MAC ordering.)

This also required the following test changes:

* reverse the sort order of the MACs in test data (so that they would trigger the bug being fixed)
* fix up the key names in `NIC2_MD` (which were under_scored instead of dash-separated)
* use a full interface dict (rather than a minimal one) for `TestConvertEc2MetadataNetworkConfig`

LP: #1876312

2 files changed, 26 insertions, 20 deletions

diff --git a/cloudinit/sources/DataSourceEc2.py b/cloudinit/sources/DataSourceEc2.py
index 4203c3a6..355b4e2f 100644
--- a/cloudinit/sources/DataSourceEc2.py
+++ b/cloudinit/sources/DataSourceEc2.py
@@ -762,13 +762,14 @@ def convert_ec2_metadata_network_config(
         netcfg['ethernets'][nic_name] = dev_config
         return netcfg
     # Apply network config for all nics and any secondary IPv4/v6 addresses
-    nic_idx = 1
     for mac, nic_name in sorted(macs_to_nics.items()):
         nic_metadata = macs_metadata.get(mac)
         if not nic_metadata:
             continue  # Not a physical nic represented in metadata
+        # device-number is zero-indexed, we want it 1-indexed for the
+        # multiplication on the following line
+        nic_idx = int(nic_metadata['device-number']) + 1
         dhcp_override = {'route-metric': nic_idx * 100}
-        nic_idx += 1
         dev_config = {'dhcp4': True, 'dhcp4-overrides': dhcp_override,
                       'dhcp6': False,
                       'match': {'macaddress': mac.lower()},
diff --git a/tests/unittests/test_datasource/test_ec2.py b/tests/unittests/test_datasource/test_ec2.py
index 9126c676..d413d1cd 100644
--- a/tests/unittests/test_datasource/test_ec2.py
+++ b/tests/unittests/test_datasource/test_ec2.py
@@ -38,6 +38,8 @@ DYNAMIC_METADATA = {
 # python3 -c 'import json
 # from cloudinit.ec2_utils import get_instance_metadata as gm
 # print(json.dumps(gm("2016-09-02"), indent=1, sort_keys=True))'
+# Note that the MAC addresses have been modified to sort in the opposite order
+# to the device-number attribute, to test LP: #1876312
 DEFAULT_METADATA = {
     "ami-id": "ami-8b92b4ee",
     "ami-launch-index": "0",
@@ -77,7 +79,7 @@ DEFAULT_METADATA = {
                     "vpc-ipv4-cidr-blocks": "172.31.0.0/16",
                     "vpc-ipv6-cidr-blocks": "2600:1f16:aeb:b200::/56"
                 },
-                "06:17:04:d7:26:0A": {
+                "06:17:04:d7:26:08": {
                     "device-number": "1",   # Only IPv4 local config
                     "interface-id": "eni-e44ef49f",
                     "ipv4-associations": {"": "172.3.3.16"},
@@ -85,7 +87,7 @@ DEFAULT_METADATA = {
                     "local-hostname": ("ip-172-3-3-16.us-east-2."
                                        "compute.internal"),
                     "local-ipv4s": "172.3.3.16",
-                    "mac": "06:17:04:d7:26:0A",
+                    "mac": "06:17:04:d7:26:08",
                     "owner-id": "950047163771",
                     "public-hostname": ("ec2-172-3-3-16.us-east-2."
                                         "compute.amazonaws.com"),
@@ -152,19 +154,19 @@ NIC1_MD_IPV4_IPV6_MULTI_IP = {
 }
 
 NIC2_MD = {
-    "device_number": "1",
-    "interface_id": "eni-043cdce36ded5e79f",
-    "local_hostname": "ip-172-31-47-221.us-east-2.compute.internal",
-    "local_ipv4s": "172.31.47.221",
+    "device-number": "1",
+    "interface-id": "eni-043cdce36ded5e79f",
+    "local-hostname": "ip-172-31-47-221.us-east-2.compute.internal",
+    "local-ipv4s": "172.31.47.221",
     "mac": "0a:75:69:92:e2:16",
-    "owner_id": "329910648901",
-    "security_group_ids": "sg-0d68fef37d8cc9b77",
-    "security_groups": "launch-wizard-17",
-    "subnet_id": "subnet-9d7ba0d1",
-    "subnet_ipv4_cidr_block": "172.31.32.0/20",
-    "vpc_id": "vpc-a07f62c8",
-    "vpc_ipv4_cidr_block": "172.31.0.0/16",
-    "vpc_ipv4_cidr_blocks": "172.31.0.0/16"
+    "owner-id": "329910648901",
+    "security-group-ids": "sg-0d68fef37d8cc9b77",
+    "security-groups": "launch-wizard-17",
+    "subnet-id": "subnet-9d7ba0d1",
+    "subnet-ipv4-cidr-block": "172.31.32.0/20",
+    "vpc-id": "vpc-a07f62c8",
+    "vpc-ipv4-cidr-block": "172.31.0.0/16",
+    "vpc-ipv4-cidr-blocks": "172.31.0.0/16"
 }
 
 SECONDARY_IP_METADATA_2018_09_24 = {
@@ -423,7 +425,7 @@ class TestEc2(test_helpers.HttprettyTestCase):
             m_find_fallback.return_value = 'eth9'
             ds.get_data()
 
-        mac1 = '06:17:04:d7:26:0A'  # IPv4 only in DEFAULT_METADATA
+        mac1 = '06:17:04:d7:26:08'  # IPv4 only in DEFAULT_METADATA
         expected = {'version': 2, 'ethernets': {'eth9': {
             'match': {'macaddress': mac1.lower()}, 'set-name': 'eth9',
             'dhcp4': True, 'dhcp6': False}}}
@@ -790,9 +792,12 @@ class TestConvertEc2MetadataNetworkConfig(test_helpers.CiTestCase):
     def setUp(self):
         super(TestConvertEc2MetadataNetworkConfig, self).setUp()
         self.mac1 = '06:17:04:d7:26:09'
+        interface_dict = copy.deepcopy(
+            DEFAULT_METADATA['network']['interfaces']['macs'][self.mac1])
+        # These tests are written assuming the base interface doesn't have IPv6
+        interface_dict.pop('ipv6s')
         self.network_metadata = {
-            'interfaces': {'macs': {
-                self.mac1: {'mac': self.mac1, 'public-ipv4s': '172.31.2.16'}}}}
+            'interfaces': {'macs': {self.mac1: interface_dict}}}
 
     def test_convert_ec2_metadata_network_config_skips_absent_macs(self):
         """Any mac absent from metadata is skipped by network config."""
@@ -875,7 +880,7 @@ class TestConvertEc2MetadataNetworkConfig(test_helpers.CiTestCase):
 
     def test_convert_ec2_metadata_network_config_handles_multiple_nics(self):
         """DHCP route-metric increases on secondary NICs for IPv4 and IPv6."""
-        mac2 = '06:17:04:d7:26:0a'
+        mac2 = '06:17:04:d7:26:08'
         macs_to_nics = {self.mac1: 'eth9', mac2: 'eth10'}
         network_metadata_both = copy.deepcopy(self.network_metadata)
         # Add 2nd nic info