openstack undercloud install or upgrade fail because certificate is not trusted

Issue

• openstack undercloud install/upgrade issue:

INFO: Failed to discover available identity versions when contacting https://x.x.x.x:13000/. Attempting to parse version from URL.
INFO: Could not determine a suitable URL for the plugin
INFO: [2019-10-22 06:33:28,217] (os-refresh-config) [ERROR] during post-configure pha
se. [Command '['dib-run-parts', '/usr/libexec/os-refresh-config/post-configure.d']' returned non-zero exit st
atus 1]
INFO: [2019-10-22 06:33:28,217] (os-refresh-config) [ERROR] Aborting...
DEBUG: An exception occurred
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 2432, in install
    _run_orc(instack_env)
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 1610, in _run_orc
    _run_live_command(args, instack_env, 'os-refresh-config')
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 673, in _run_live_command
    raise RuntimeError('%s failed. See log for details.' % name)
RuntimeError: os-refresh-config failed. See log for details.
ERROR: 
#############################################################################
Undercloud install failed.