Public bug reported: Since #114 all network interfaces get IPs and a default route, with a metric based on `nic_idx`. `nic_idx` isn't derived from the EC2 device- number, but from sorting by MAC address:
https://github.com/canonical/cloud- init/blob/6600c642af3817fe5e0170cb7b4eeac4be3c60eb/cloudinit/sources/DataSourceEc2.py#L766 A machine with multiple interfaces, where the MAC addresses aren't in order, will end up with the wrong metric. For example, if eth0 has a MAC address that sorts before eth1, the default route for eth1 will be given metric 100, while eth0 will get 200. This wasn't picked up in tests (e.g. https://paste.ubuntu.com/p/jw6Wws5Jhk/) because interfaces are typically assigned in MAC address order. This isn't true when creating an additional network interface in EC2, or creating an instance from pre- existing interfaces. ** Affects: cloud-init Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to cloud-init. https://bugs.launchpad.net/bugs/1876312 Title: route metric on multihomed ec2 instances is based on mac address instead of device-number Status in cloud-init: New Bug description: Since #114 all network interfaces get IPs and a default route, with a metric based on `nic_idx`. `nic_idx` isn't derived from the EC2 device-number, but from sorting by MAC address: https://github.com/canonical/cloud- init/blob/6600c642af3817fe5e0170cb7b4eeac4be3c60eb/cloudinit/sources/DataSourceEc2.py#L766 A machine with multiple interfaces, where the MAC addresses aren't in order, will end up with the wrong metric. For example, if eth0 has a MAC address that sorts before eth1, the default route for eth1 will be given metric 100, while eth0 will get 200. This wasn't picked up in tests (e.g. https://paste.ubuntu.com/p/jw6Wws5Jhk/) because interfaces are typically assigned in MAC address order. This isn't true when creating an additional network interface in EC2, or creating an instance from pre-existing interfaces. To manage notifications about this bug go to: https://bugs.launchpad.net/cloud-init/+bug/1876312/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
