CentOS 8 cloud images not working under VM tests

[John Snow]

This test doesn't appear to work for me:

def build_image(self, img):
    cimg = 
self._download_with_cache("https://cloud.centos.org/centos/8/x86_64/images/CentOS-8-GenericCloud-8.3.2011-20201204.2.x86_64.qcow2";)
    img_tmp = img + ".tmp"
    subprocess.check_call(["ln", "-f", cimg, img_tmp])
    self.exec_qemu_img("resize", img_tmp, "50G")
    self.boot(img_tmp, extra_args = ["-cdrom", self.gen_cloud_init_iso()])
    self.wait_ssh()
    ^^^^^^^^^^^^^^^

It appears to be expecting to be able to use passwordless entry, but
that doesn't appear to actually work in this case.

It looks like the cloud iso generate step is supposed to handle
setting up keys -- and everything appears as if it's working -- but I
get SSH timeouts at this step.

>From what I can see:

DEBUG:root:ssh_cmd: ssh -t -o StrictHostKeyChecking=no -o
UserKnownHostsFile=/dev/null -o ConnectTimeout=1 -p 41729 -i
/home/jsnow/src/qemu/bin/git/vm-test-35u779h4.tmp/id_rsa -o
SendEnv=https_proxy -o SendEnv=http_proxy -o SendEnv=ftp_proxy -o
SendEnv=no_proxy qemu@127.0.0.1 exit 0
Warning: Permanently added '[127.0.0.1]:41729' (ED25519) to the list
of known hosts.
qemu@127.0.0.1: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

...and the /home/jsnow/src/qemu/bin/git/vm-test-35u779h4.tmp/id_rsa
file looks identical to the qemu.git/tests/keys/id_rsa file, save for
a missing trailing newline.

>From a subsequent run, turning SSH debug on, I see this:

debug1: Offering public key:
/home/jsnow/src/qemu/bin/git/vm-test-o_x2vdwo.tmp/id_rsa RSA
SHA256:6TUK9PSgWR+CbTEKA6E9IyizVjt2ZW5ble/Mg4wUiao explicit
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51

... Which looks like the usual kind of bog-standard "Unrecognized key"
kind of answer, IIUC.

Is this working for anyone else, or can anyone offer some debugging
tips on what's gone wrong here? I'm assuming it worked as of
fb1fa97c69ca2299158229c78fea68c4036e6c1b ... Daniel, any clues?

--js