* tstest/natlab/vmtest: make cloud VM boot robust without KVM
Adding heavier distro images (Fedora) surfaced several ways the cloud VM
boot path breaks under TCG software emulation (no /dev/kvm), especially
with multiple concurrent VMs on few cores.
- Add a virtio-rng device to the cloud path so early boot doesn't block in
getrandom() waiting for the CRNG to seed.
- When no hardware acceleration is available, relax the stuck-console
watchdog (tuned for KVM's ~1-2s first output) and serialize VM boots so a
heavy guest doesn't starve its siblings' emulation threads.
- Bound the bring-up context to the test deadline and dump each VM's console
on failure, so a hang surfaces as a diagnosable Fatalf instead of an
opaque `go test -timeout` panic (which skips cleanups).
Fixestailscale/corp#44794
Updates tailscale/corp#44793
Signed-off-by: Brendan Creane <bcreane@gmail.com>
* tstest/natlab/vmtest: add Fedora and DNS-backend test coverage
Add the first RHEL-family distro and the machinery to assert and provision
distinct DNS backends, so adding a distro isn't "basically equivalent" to
the others.
- Add a Fedora 43 image (NetworkManager + systemd-resolved, SELinux
enforcing). restorecon-relabel the curl'd binaries so they exec under
enforcing mode.
- Add DNSBackend/AssertDNSBackend, reading the dns_manager_linux_mode_*
clientmetric to assert which backend tailscaled selected.
- Add a WithDNSMode node option. WithDNSMode(DNSDirect) masks
systemd-resolved and writes a plain resolv.conf pointing at natlab's fake
DNS, forcing the direct backend -- so one image covers multiple backends.
Fixestailscale/corp#44796
Updates tailscale/corp#44793
Signed-off-by: Brendan Creane <bcreane@gmail.com>
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Signed-off-by: Brendan Creane <bcreane@gmail.com>
Brendan CreaneandGitHub
a7cb5745a2