vm fails to boot due to conflicting network configuration when user switches from netplan to eni

[Anh Vo (MSFT)]

When the user provisions a bionic VM the first time, cloudinit picks netplan as the renderer since other renderers are not available (e.g., eni). Cloudinit then wrote a netplan file (50-cloud-init.yaml). If the user installs ifupdown and fail to manually remove netplan, the vm will fail to boot if there are conflicting changes happened to the NIC, such as a MAC address change. The reason is that when ifupdown is installed cloudinit will prefer eni at boot time and the previously written netplan configuration file now contains bad network configuration.

This was discussed in cloud-init IRC channel and the general consensus is that while the user should be removing netplan when installing ifupdown, it is not a hard requirement as netplan and ifupdown can actually coexist. Cloudinit should consider removing conflicting netplan file that it wrote when it chooses eni.

[Ryan Harper (raharper)]

Do you happen to have a cloud-init collect-logs output ? I suspect it's easy enough to recreate bug if you've already got logs available, please attach.

[Launchpad Janitor (janitor)]

[Expired for cloud-init (Ubuntu) because there has been no activity for 60 days.]

[Thorsten Meinl (sithmein)]

In my opinion this is serious bug. I created an AWS AMI using packer and one of the installed packages (salt-minion) pulled in ifupdown. This then broke network connectivity of instances started from the custom AMI. I took me five hours to find out what the problem was.