Fix missing X-OpenStack-Request-ID header

Request ID is essential in operating OpenStack services, especially
when troubleshooting some API problems. It allows us to find out
the log lines actually related to a specific request.

However watcher api hasn't returned it properly, so operators had no
way to determine the exact ID they should search.

Add RequestID middleware to return the id in X-OpenStack-Request-Id
header, which is globally used.

Closes-Bug: #2122350
Change-Id: Ie4a8307e8e7e981cedbeaf5fe731dbd47a50bade
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

watcher/tests/api/test_root.py

@@ -24,6 +24,12 @@ class TestRoot(base.FunctionalTest):
         # Check fields are not empty
         [self.assertNotIn(f, ['', []]) for f in data.keys()]
 
+    # NOTE(tkajinam): Request ID should be present in any request so we verify
+    # it only at the root path.
+    def test_request_id(self):
+        resp = self.get_json('/', path_prefix='', return_json=False)
+        self.assertIn('X-OpenStack-Request-Id', resp.headers)
+
 
 class TestV1Root(base.FunctionalTest):