Support X.latest format for OS_COMPUTE_API_VERSION

OSC don't support to use "X.latest" format in order to talk with the
latest nova microversion API, that is very helpful shortcut usage to
use new nova side features, this patch implement it.

Change-Id: I87918addff1f50fbc6eb72ca82b31813330753b5
Closes-Bug: #1561838

openstackclient/compute/client.py

@@ -41,8 +41,18 @@ def make_client(instance):
         version = _compute_api_version
     else:
         version = instance._api_version[API_NAME]
+        from novaclient import api_versions
+        # convert to APIVersion object
+        version = api_versions.get_api_version(version)
 
-    LOG.debug('Instantiating compute client for V%s', version)
+    if version.is_latest():
+        import novaclient
+        # NOTE(RuiChen): executing version discovery make sense, but that need
+        #                an initialized REST client, it's not available now,
+        #                fallback to use the max version of novaclient side.
+        version = novaclient.API_MAX_VERSION
+
+    LOG.debug('Instantiating compute client for %s', version)
 
     # Set client http_log_debug to True if verbosity level is high enough
     http_log_debug = utils.get_effective_log_level() <= logging.DEBUG
@@ -91,30 +101,27 @@ def check_api_version(check_version):
     """
 
     # Defer client imports until we actually need them
-    try:
-        from novaclient import api_versions
-    except ImportError:
-        # Retain previous behaviour
-        return False
-
     import novaclient
+    from novaclient import api_versions
 
     global _compute_api_version
 
-    # Copy some logic from novaclient 2.27.0 for basic version detection
+    # Copy some logic from novaclient 3.3.0 for basic version detection
     # NOTE(dtroyer): This is only enough to resume operations using API
     #                version 2.0 or any valid version supplied by the user.
     _compute_api_version = api_versions.get_api_version(check_version)
 
-    if _compute_api_version > api_versions.APIVersion("2.0"):
-        if not _compute_api_version.matches(
-            novaclient.API_MIN_VERSION,
-            novaclient.API_MAX_VERSION,
-        ):
-            raise exceptions.CommandError(
-                "versions supported by client: %s - %s" % (
-                    novaclient.API_MIN_VERSION.get_string(),
-                    novaclient.API_MAX_VERSION.get_string(),
-                ),
-            )
+    # Bypass X.latest format microversion
+    if not _compute_api_version.is_latest():
+        if _compute_api_version > api_versions.APIVersion("2.0"):
+            if not _compute_api_version.matches(
+                novaclient.API_MIN_VERSION,
+                novaclient.API_MAX_VERSION,
+            ):
+                raise exceptions.CommandError(
+                    "versions supported by client: %s - %s" % (
+                        novaclient.API_MIN_VERSION.get_string(),
+                        novaclient.API_MAX_VERSION.get_string(),
+                    ),
+                )
     return True

releasenotes/notes/bug-1561838-3a006a8263d7536d.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - Support X.latest format for OS_COMPUTE_API_VERSION in order to talk with
+    the latest nova microversion API, that is very helpful shortcut usage to
+    use new nova side features.
+    [Bug `1561838 <https://bugs.launchpad.net/python-openstackclient/+bug/1561838>`_]