Check launched server for x86-64-v2/sse4_2 support

The "UBI" that the latest Keycloak images are based on has a glibc
compiled to only work on x86-64-v2 systems, and in some regions we
seem to sometimes get hypervisors reporting older processor
architectures where it won't work. Check CPU flags for sse4_2
support as an indicator, and abort launching if it's not present.

Change-Id: Ib0f482a939f94e801c82f3583e0a58dc4ca1f35c

launch/src/opendev_launch/launch_node.py

@@ -131,6 +131,9 @@ def bootstrap_server(server, key, name, volume_device, keep,
 
     ssh_client = utils.ssh_connect(ip, 'root', ssh_kwargs, timeout=timeout)
 
+    if "sse4_2" not in ssh_client.ssh('cat /proc/cpuinfo', quiet=True)[1]:
+        raise Exception("CPU does not support x86-64-v2 (sse4_2)")
+
     if not ignore_ipv6:
         # Something up with RAX images that they have the ipv6 interface in
         # /etc/network/interfaces but eth0 hasn't noticed yet; reload it

launch/src/opendev_launch/sshclient.py

@@ -38,14 +38,16 @@ class SSHClient(object):
         client.connect(ip, username=username, password=password, pkey=pkey)
         self.client = client
 
-    def ssh(self, command, error_ok=False):
+    def ssh(self, command, error_ok=False, quiet=False):
         stdin, stdout, stderr = self.client.exec_command(command)
         print('--- ssh: "%s" ---' % command)
-        print(' -- stdout --')
+        if not quiet:
+            print(' -- stdout --')
         output = ''
         for x in stdout:
             output += x
-            sys.stdout.write(" | " + x)
+            if not quiet:
+                sys.stdout.write(" | " + x)
         ret = stdout.channel.recv_exit_status()
         print(" -- stderr --")
         for x in stderr: