test(qemu): replace Fedora Cloud image with Alpine Linux tiny image

## Motivation

The Fedora Cloud qcow2 images used in QEMU driver tests weigh ~556 MB
(x86_64) + ~519 MB (aarch64) = ~1.1 GB total, taking ~1 minute to
download on every CI cache miss and consuming significant bandwidth.

## Image replacement

Replace with Alpine Linux 3.22.4 UEFI tiny cloud images from
dl-cdn.alpinelinux.org:

  x86_64:  556 MB → 127 MB  (77% reduction)
  aarch64: 519 MB → 151 MB  (71% reduction)
  Total:  ~1076 MB → ~278 MB (74% reduction)

Alpine's nocloud tiny images support UEFI boot on both architectures
and use tiny-cloud (a minimal cloud-init alternative) that reads the
standard NoCloud CIDATA vfat volume the QEMU driver already generates.

## Driver changes (driver.py)

tiny-cloud has two behavioural differences from full cloud-init:

1. Hostname: tiny-cloud reads @hostname from the YAML key 'hostname'
   in meta-data, not 'local-hostname'. Add 'hostname' alongside
   'local-hostname' so both cloud-init and tiny-cloud set it correctly.

2. Password: tiny-cloud does not support plain_text_passwd in the users
   stanza. Add a runcmd entry ('echo user:pass | chpasswd') which
   tiny-cloud does execute. Full cloud-init images are unaffected.

## Test changes (driver_test.py)

Alpine has no SELinux and uses a different default shell prompt:

- Remove 'sudo setenforce 0' (no SELinux on Alpine).
- Update post-login prompt match from bash '[user@host ~]$' to
  Alpine ash 'host:~$'.
- Relax 'uname -r' assertion from the Fedora-specific kernel string
  to a non-empty check.
- Press Enter when the GRUB countdown appears to skip the 10 s wait
  (detected via 'automatically in '; if the image already booted past
  GRUB the code falls through directly to the login prompt).

## SSH: TCP hostfwd instead of vsock

Fedora cloud images ship systemd-ssh-generator (part of systemd ≥ 256)
which automatically binds sshd to AF_VSOCK port 22 when booting inside
a VM. Alpine uses OpenRC — no systemd, no generator — so sshd only
listens on TCP.

The fix: allocate a free host port at test start and pass it as
hostfwd={'ssh': {protocol, hostaddr, hostport, guestport=22}}. Because
hostfwd entries are written to children['ssh'] after the VsockNetwork,
they override it, so qemu.shell() transparently uses TCP without any
other code changes.

Author: mangelajo

.github/workflows/python-tests.yaml

@@ -120,19 +120,19 @@ jobs:
         run: |
           brew install renode/tap/renode
 
-      - name: Cache Fedora Cloud images
-        id: cache-fedora-cloud-images
+      - name: Cache Alpine cloud images
+        id: cache-alpine-cloud-images
         uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
         with:
           path: python/packages/jumpstarter-driver-qemu/images
-          key: fedora-cloud-43-1.6
+          key: alpine-3.22.4-uefi-tiny
 
-      - name: Download Fedora Cloud images
-        if: steps.cache-fedora-cloud-images.outputs.cache-hit != 'true'
+      - name: Download Alpine cloud images
+        if: steps.cache-alpine-cloud-images.outputs.cache-hit != 'true'
         run: |
           for arch in aarch64 x86_64; do
-            curl -L --fail --output "python/packages/jumpstarter-driver-qemu/images/Fedora-Cloud-Base-Generic-43-1.6.${arch}.qcow2" \
-              "https://iad.mirror.rackspace.com/fedora/releases/43/Cloud/${arch}/images/Fedora-Cloud-Base-Generic-43-1.6.${arch}.qcow2"
+            curl -L --fail --output "python/packages/jumpstarter-driver-qemu/images/nocloud_alpine-3.22.4-${arch}-uefi-tiny-r0.qcow2" \
+              "https://dl-cdn.alpinelinux.org/alpine/v3.22/releases/cloud/nocloud_alpine-3.22.4-${arch}-uefi-tiny-r0.qcow2"
           done
 
       - name: Run pytest

python/packages/jumpstarter-driver-qemu/jumpstarter_driver_qemu/driver.py

@@ -512,6 +512,7 @@ def cidata(self) -> TemporaryDirectory:
                 {
                     "instance-id": str(self.uuid),
                     "local-hostname": self.hostname,
+                    "hostname": self.hostname,
                 }
             )
         )
@@ -528,6 +529,13 @@ def cidata(self) -> TemporaryDirectory:
                             "sudo": "ALL=(ALL) NOPASSWD:ALL",
                         }
                     ],
+                    # runcmd sets the password explicitly for cloud-init implementations
+                    # that do not support plain_text_passwd (e.g. Alpine's tiny-cloud).
+                    # cloud-init ignores runcmd entries it doesn't understand, so this
+                    # is safe to include unconditionally.
+                    "runcmd": [
+                        f"echo '{self.username}:{self.password}' | chpasswd",
+                    ],
                 }
             )
         )

python/packages/jumpstarter-driver-qemu/jumpstarter_driver_qemu/driver_test.py

@@ -2,6 +2,7 @@
 import json
 import os
 import platform
+import socket
 import sys
 import tarfile
 from pathlib import Path
@@ -59,26 +60,34 @@ def get_native_arch_config():
 def test_driver_qemu(tmp_path, ovmf):
     arch, ovmf_arch = get_native_arch_config()
 
+    # Alpine uses OpenRC (not systemd), so systemd-ssh-generator does not run
+    # and sshd never binds to AF_VSOCK. Use a TCP hostfwd instead so that
+    # qemu.shell() connects over standard TCP SSH, which always works.
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as _s:
+        _s.bind(("127.0.0.1", 0))
+        ssh_host_port = _s.getsockname()[1]
+
     with serve(
         Qemu(
             arch=arch,
             default_partitions={
                 "OVMF_CODE.fd": ovmf / ovmf_arch / "code.fd",
                 "OVMF_VARS.fd": ovmf / ovmf_arch / "vars.fd",
             },
+            hostfwd={"ssh": {"protocol": "tcp", "hostaddr": "127.0.0.1", "hostport": ssh_host_port, "guestport": 22}},
         )
     ) as qemu:
         hostname = qemu.hostname
         username = qemu.username
         password = qemu.password
 
-        cached_image = Path(__file__).parent.parent / "images" / f"Fedora-Cloud-Base-Generic-43-1.6.{arch}.qcow2"
+        cached_image = Path(__file__).parent.parent / "images" / f"nocloud_alpine-3.22.4-{arch}-uefi-tiny-r0.qcow2"
 
         if cached_image.exists():
             qemu.flasher.flash(cached_image.resolve())
         else:
             qemu.flasher.flash(
-                f"https://download.fedoraproject.org/pub/fedora/linux/releases/43/Cloud/{arch}/images/Fedora-Cloud-Base-Generic-43-1.6.{arch}.qcow2",
+                f"https://dl-cdn.alpinelinux.org/alpine/v3.22/releases/cloud/nocloud_alpine-3.22.4-{arch}-uefi-tiny-r0.qcow2",
             )
 
         qemu.power.on()
@@ -88,16 +97,18 @@ def test_driver_qemu(tmp_path, ovmf):
 
         with qemu.console.pexpect() as p:
             p.logfile = sys.stdout.buffer
-            p.expect_exact(f"{hostname} login:", timeout=600)
+            # Press Enter if GRUB is waiting; if it already booted, go straight to login
+            idx = p.expect_exact(["automatically in ", f"{hostname} login:"], timeout=60)
+            if idx == 0:
+                p.sendline("")
+                p.expect_exact(f"{hostname} login:", timeout=600)
             p.sendline(username)
             p.expect_exact("Password:")
             p.sendline(password)
-            p.expect_exact(f"[{username}@{hostname} ~]$")
-            p.sendline("sudo setenforce 0")
-            p.expect_exact(f"[{username}@{hostname} ~]$")
+            p.expect_exact(f"{hostname}:~$")
 
         with qemu.shell() as s:
-            assert s.run("uname -r").stdout.strip() == f"6.17.1-300.fc43.{arch}"
+            assert s.run("uname -r").stdout.strip() != ""
 
         qemu.power.off()