[Bug] Misleading error message when opening .yml file

[ndormann]

🐛 Bug

Description

The error message doesn't reflect that Hydra only accepts .yml files. The error message states "Cannot find primary config 'config.yml'" which hints at a problem with an incorrect path setup or a missing file. However, the config file exists and the path is correct. Only the file ending is not supported.

Checklist

• I checked on the latest version of Hydra
• I created a minimal repro (See this for tips).

To reproduce

** Minimal Code/Config snippet to reproduce **
from hydra import initialize, compose

with initialize(version_base=None, config_path="cloud_app/conf"):
cfg = compose("config.yml",overrides=["+db=mysql"])
print(cfg)

** Stack trace/error message **

MissingConfigException: Cannot find primary config 'config.yml'. Check that it's in your config search path.

Config search path:
	provider=hydra, path=pkg://hydra.conf
	provider=main, path=file:///home/user/notebooks/cloud_app/conf
	provider=schema, path=structured://

Expected Behavior

Output appropriate Error Message:

• WrongFileEndingException: Only .yaml files are expected as config files.

System information

• Hydra Version : 1.3.2
• Python version : 3.9.19
• Virtual environment type and version : conda 4.12.0
• Operating system : ubuntu

Related Issues and PRs

Previous discussions to support .yml or not (concluded not to support for now): #398 #1050
Add note in documentation: #1298

[odelalleau]

It's not entirely trivial to fix in the general case due to how it's currently implemented, but I agree this is confusing.

What would be easy is to catch the ".yml" usage and raise a clear exception when it happens => we should probably start with that. Something like

--- a/hydra/plugins/config_source.py
+++ b/hydra/plugins/config_source.py
@@ -119,7 +119,10 @@ class ConfigSource(Plugin):
     @staticmethod
     def _normalize_file_name(filename: str) -> str:
         supported_extensions = [".yaml"]
-        if not version.base_at_least("1.2"):
+        if version.base_at_least("1.2"):
+            if filename.endswith(".yml"):
+                raise RuntimeError("bad extension")
+        else:
             supported_extensions.append(".yml")
             if filename.endswith(".yml"):
                 deprecation_warning(

(feel free to submit a clean PR if you want to)

[ndormann]

Thank you, I have adopted your idea and submitted a corresponding PR.
Tests are failing, but I assume that is a general problem with your CI at the moment?