configure: Add function to enable the SSH daemon

The `configure.enable_sshd` function enables the SSH daemon in the
target system. It generates host keys and sets the daemon to start at
boot. This function is called by `configure.configure` if the VM
definition contains at least one network interface.

src/mkvm/configure.py

@@ -75,6 +75,16 @@ def enable_console_login(mountpoint, driver):
                 f.write(line)
 
 
+def enable_sshd(mountpoint):
+    cmd = ['chroot', mountpoint, 'ssh-keygen', '-A']
+    output = subprocess.check_output(cmd)
+    if output:
+        log.info(output.decode().strip())
+    path = os.path.join(mountpoint, 'etc/runlevels/default/sshd')
+    if not os.path.exists(path):
+        os.symlink('/etc/init.d/sshd', path)
+
+
 def run_custom_script(mountpoint, script):
     cmd = ['chroot', mountpoint, '/bin/sh']
     env = CUSTOM_SCRIPT_ENV.copy()
@@ -98,6 +108,8 @@ def configure(vm):
         set_hostname(vm.mountpoint, vm.fqdn)
     if vm.console:
         enable_console_login(vm.mountpoint, vm.console)
+    if vm.net_ifaces:
+        enable_sshd(vm.mountpoint)
     if vm.customize:
         run_custom_script(vm.mountpoint, vm.customize)