Debian 10 cloud-init waiting for DHCP on boot with static network configuration

cloud-initdebian

Running Debian 10 Buster image (created with build-openstack-debian-image --release buster) with cloud-init image created by cloud-localds -v --disk-format raw --filesystem iso9660 --network-config=network-config-v2.yaml seed.img user-data.yaml.

Problem is that boot is delayed by waiting for DHCP, although I have a valid network configuration and it's applied after this delay.

[    3.619937] cloud-init[210]: Cloud-init v. 20.2 running 'init-local' at Sun, 10 Jan 2021 10:50:20 +0000. Up 3.40 seconds.
[  OK  ] Started Initial cloud-init job (pre-networking).
[  OK  ] Reached target Network (Pre).
         Starting Raise network interfaces...
[  OK  ] Started ifup for eth0.
[     *] A start job is running for Raise network interfaces (35s / 5min 1s)

What can I do to skip this delay?

I can provide more info if needed. Thanks.

# systemd-analyze blame
     1min 2.639s networking.service
           951ms cloud-init-local.service
           773ms cloud-init.service
           657ms cloud-final.service
           540ms cloud-config.service
           421ms dev-vda1.device
           310ms ifupdown-pre.service

My network-config-v2.yaml:

version: 2
renderer: networkd
ethernets:
  eth0:
    match:
      name: e*
    addresses:
      - private.ipv4/24
      - public.ipv4/32
      - ipv6/64
    gateway4: private.ipv4
    routes:
      - to: 0.0.0.0/0
        via: private.ipv4
    gateway6: ipv6
    nameservers:
      addresses:
        - ipv4
        - ipv6
      search: [domain.com]

Best Answer

I encountered the sample problem -- using a static network configuration (NoCloud provider meta-data ENI, or network-config v1/v2) does not disable the DHCP client.

Seems a network config is applied from a template (/etc/network/cloud-interfaces-template) before the cloud-init configuration is written.

auto $INTERFACE
allow-hotplug $INTERFACE

iface $INTERFACE inet dhcp

You can test that this template is the culprit by changing the cloud-image before first start:
(patching the image as changing network config in e.g. bootcmd is too late.)

qemu-nbd --connect=/dev/nbd0 /tmp/debian-10-genericcloud-amd64-20210208-542.qcow2
fdisk /dev/nbd0 -l
mkdir /tmp/nbd
mount /dev/nbd0p1 /tmp/nbd
sed -i 's/dhcp/manual/' /tmp/nbd/etc/network/cloud-interfaces-template
umount /tmp/nbd
rmdir /tmp/nbd
qemu-nbd --disconnect /dev/nbd0

I still need to find a way to apply this change or prevent the use of this template with cloud-init though.

That template seems to be processed by /etc/network/cloud-ifupdown-helper, so that script could be changed or influenced perhaps.

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