feat: validate_env cloud flag support

closes: #413

Change-Id: I0d3890e37ccbe63212fe03571e370fdde4b44913

README.md

@@ -82,6 +82,7 @@ QUADS automates the future scheduling, end-to-end provisioning and delivery of b
          * [Validation using Debug Mode](#validation-using-debug-mode)
          * [Skipping Past Network Validation](#skipping-past-network-validation)
          * [Skipping Past Foreman Validation](#skipping-past-foreman-validation)
+         * [Validate Only a Specific Cloud](#validate-only-a-specific-cloud)
          * [Mapping Internal VLAN Interfaces to Problem Hosts](#mapping-internal-vlan-interfaces-to-problem-hosts)
       * [Contact QUADS Developers](#contact-quads-developers)
       * [QUADS Talks and Media](#quads-talks-and-media)
@@ -1337,6 +1338,13 @@ db.cloud.update({"name": "cloud23"}, {$set:{'provisioned':true}}
 
 * More information on manual intervention and overrides via MongoDB can be [found here](/docs/interact-mongodb.md)
 
+### Validate Only a Specific Cloud
+
+* If you want to validate only a certain cloud you can do so by specifying the cloud's name with the `--cloud` flag.
+```bash
+/opt/quads/tools/validate_env.py --cloud cloud01
+```
+
 ### Mapping Internal VLAN Interfaces to Problem Hosts
 You might have noticed that we configure our [Foreman](https://github.com/redhat-performance/quads/tree/master/templates/foreman) templates to drop `172.{16,17,18,19}.x` internal VLAN interfaces which correspond to the internal, QUADS-managed multi-tenant interfaces across a set of hosts in a cloud assignment.
 

quads/tools/validate_env.py

@@ -312,6 +312,10 @@ async def validate_env(self):
 
 def main(_args, _loop):
     clouds = Cloud.objects(validated=False, provisioned=True, name__ne="cloud01")
+    if _args.cloud:
+        clouds = [cloud for cloud in clouds if cloud.name == _args.cloud]
+        if len(clouds) == 0:
+            logger.error("No cloud with this name.")
     for _cloud in clouds:
         _schedule_count = Schedule.current_schedule(cloud=_cloud).count()
         if _schedule_count and _cloud.wipe:
@@ -337,6 +341,12 @@ def main(_args, _loop):
         default=False,
         help="Show debugging information.",
     )
+    parser.add_argument(
+        "--cloud",
+        nargs=1,
+        default="",
+        help="Run validation only on specified cloud."
+    )
     args = parser.parse_args()
 
     level = logging.INFO