Switch to Ubuntu Minimal cloud image - #286
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nirs
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August 3, 2026 17:18
The server cloud image is ~850MB which is excessive for testing vmnet-helper. Switch to the minimal cloud image (~407MB for amd64v3, ~390MB for arm64) — about half the download size and disk footprint (1.2GB vs 2.6GB per VM). Use x86-64-v3 variant for Intel since all target machines are macOS 14+ (2018 Coffee Lake or newer). Drop initrd for direct kernel boot — the minimal kernel has virtio_blk and ext4 built-in so we can boot without it. Switch from root=LABEL=cloudimg-rootfs to root=/dev/vda1 since the minimal image uses PARTUUID instead of filesystem labels.
Switching to Ubuntu Minimal cloud image reduced CI boot times from 3:30-4:40 minutes to 1:15-1:54 minutes. With 300s timeout we still have over a minute of margin. This reverts commit 5b0d24b.
This service may block boot for 2 minutes waiting for all network
interfaces to be fully configured. With the minimal cloud image, it
prevents sshd from accepting connections (via socket activation
dependency on network-online.target).
We only need eth0 with DHCP from vmnet and don't need the
network-online target.
Use bootcmd (runs during cloud-init-local, before the service starts)
for vfkit, and systemd.mask= kernel parameter for QEMU direct boot.
Boot time with minimal image before masking:
Startup finished in 68ms (kernel) + 2min 1.668s (userspace)
After masking:
Startup finished in 68ms (kernel) + 1.668s (userspace) = 1.737s
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Switch to Ubuntu Minimal cloud image
Switch test VMs from the Ubuntu server cloud image (~850MB) to the
minimal cloud image (~407MB for amd64v3, ~390MB for arm64). This cuts
CI boot times from 2:30-5:00 minutes to 1:15-1:54, and local VM disk
usage from 2.6GB to 1.2GB per VM.
Changes:
ext4 built-in)
PARTUUID, not filesystem labels)
Boot time improvement (local, vfkit arm64):
CI "Start example VM" step improvement:
Example boot in 1.7 seconds