Add password authentication to Redis ports (#2952)

* Implement Redis authentication

* Throw exception for legacy Ray

* Add test

* Formatting

* Fix bugs in CLI

* Fix bugs in Raylet

* Move default password to constants.h

* Use pytest.fixture

* Fix bug

* Authenticate using formatted strings

* Add missing passwords

* Add test

* Improve authentication of async contexts

* Disable Redis authentication for credis

* Update test for credis

* Fix rebase artifacts

* Fix formatting

* Add workaround for issue #3045

* Increase timeout for test

* Improve C++ readability

* Fixes for CLI

* Add security docs

* Address comments

* Address comments

* Adress comments

* Use ray.get

* Fix lint

python/ray/workers/default_worker.py

@@ -24,6 +24,12 @@ parser.add_argument(
     required=True,
     type=str,
     help="the address to use for Redis")
+parser.add_argument(
+    "--redis-password",
+    required=False,
+    type=str,
+    default=None,
+    help="the password to use for Redis")
 parser.add_argument(
     "--object-store-name",
     required=True,
@@ -67,6 +73,7 @@ if __name__ == "__main__":
     info = {
         "node_ip_address": args.node_ip_address,
         "redis_address": args.redis_address,
+        "redis_password": args.redis_password,
         "store_socket_name": args.object_store_name,
         "manager_socket_name": args.object_store_manager_name,
         "local_scheduler_socket_name": args.local_scheduler_name,
@@ -81,7 +88,10 @@ if __name__ == "__main__":
     tempfile_services.set_temp_root(args.temp_dir)
 
     ray.worker.connect(
-        info, mode=ray.WORKER_MODE, use_raylet=(args.raylet_name is not None))
+        info,
+        mode=ray.WORKER_MODE,
+        use_raylet=(args.raylet_name is not None),
+        redis_password=args.redis_password)
 
     error_explanation = """
   This error is unexpected and should not have happened. Somehow a worker