Allow aliases for run_opt

Summary:
Lets allow aliases for a runopt. This will give downstream users to have multiple ways of accessing the same runopt. 
1. Modify add() to accept this and add a new optional aliases List[str] that will store this. 
2. Modify resolve() to check if a different alias is already used in cfg i.e if the "run_as" and "Run_As" are aliases for the same one, we dont allow for both to be present in the cfg.

Differential Revision: D84157870

Author: AbishekS

torchx/specs/api.py

@@ -896,6 +896,7 @@ class runopt:
     opt_type: Type[CfgVal]
     is_required: bool
     help: str
+    aliases: Optional[List[str]] = None
 
     @property
     def is_type_list_of_str(self) -> bool:
@@ -1029,9 +1030,19 @@ def resolve(self, cfg: Mapping[str, CfgVal]) -> Dict[str, CfgVal]:
 
         resolved_cfg: Dict[str, CfgVal] = {**cfg}
 
+        cfg_keys_checked = set()
+
         for cfg_key, runopt in self._opts.items():
             val = resolved_cfg.get(cfg_key)
-
+            if val is not None:
+                if cfg_key not in cfg_keys_checked:
+                    cfg_keys_checked.update(runopt.aliases or [])
+                else:
+                    raise InvalidRunConfigException(
+                        f"Run option: {cfg_key}, is an alias of another run option already used in the cfg.",
+                        cfg_key,
+                        cfg,
+                    )
             # check required opt
             if runopt.is_required and val is None:
                 raise InvalidRunConfigException(
@@ -1145,7 +1156,7 @@ def cfg_from_json_repr(self, json_repr: str) -> Dict[str, CfgVal]:
 
     def add(
         self,
-        cfg_key: str,
+        cfg_key: Union[str, List[str]],
         type_: Type[CfgVal],
         help: str,
         default: CfgVal = None,
@@ -1156,6 +1167,7 @@ def add(
         value (if any). If the ``default`` is not specified then this option
         is a required option.
         """
+        aliases = cfg_key if isinstance(cfg_key, list) else [cfg_key]
         if required and default is not None:
             raise ValueError(
                 f"Required option: {cfg_key} must not specify default value. Given: {default}"
@@ -1166,8 +1178,14 @@ def add(
                     f"Option: {cfg_key}, must be of type: {type_}."
                     f" Given: {default} ({type(default).__name__})"
                 )
-
-        self._opts[cfg_key] = runopt(default, type_, required, help)
+        opt = runopt(default, type_, required, help, aliases)
+        for alias in aliases:
+            if alias in self._opts:
+                raise ValueError(
+                    f"Option: {alias} already exists. "
+                    f"Cannot add another option with the same name."
+                )
+            self._opts[alias] = opt
 
     def update(self, other: "runopts") -> None:
         self._opts.update(other._opts)

torchx/specs/test/api_test.py

@@ -578,6 +578,20 @@ def test_runopts_add(self) -> None:
         # this print is intentional (demonstrates the intended usecase)
         print(opts)
 
+    def test_runopts_add_with_aliases(self) -> None:
+        opts = runopts()
+        opts.add(["run_as", "run_as_alias"], type_=str, help="run as user")
+        self.assertEqual(2, len(opts._opts))
+        self.assertIsNotNone(opts._opts["run_as"].aliases)
+        self.assertEqual(2, len(opts._opts["run_as"].aliases or []))
+        self.assertEqual(2, len(opts._opts["run_as_alias"].aliases or []))
+
+    def test_runopts_resolve_with_aliases(self) -> None:
+        opts = runopts()
+        opts.add(["run_as", "run_as_alias"], type_=str, help="run as user")
+        with self.assertRaises(InvalidRunConfigException):
+            opts.resolve({"run_as": "foobar", "run_as_alias": "foobar_alias"})
+
     def get_runopts(self) -> runopts:
         opts = runopts()
         opts.add("run_as", type_=str, help="run as user", required=True)