Merge pull request #228 from lsst-sqre/tickets/DM-38425

DM-38425: Be more robust when getting the running image

CHANGELOG.md

@@ -4,6 +4,12 @@ Versioning follows [semver](https://semver.org/).
 
 Dependencies are updated to the latest available version during each release. Those changes are not noted here explicitly.
 
+## 5.0.1 (unreleased)
+
+### Bug fixes
+
+- The code to determine the Docker reference and description of the running Nublado image is now more robust against unexpected output.
+
 ## 5.0.0 (2023-03-22)
 
 ### Backwards-incompatible changes

src/mobu/services/business/nublado.py

@@ -247,10 +247,16 @@ async def create_session(
             session = await self._client.create_labsession(notebook_name)
         with self.timings.start("execute_setup", self.annotations()):
             image_data = await self._client.run_python(session, _GET_IMAGE)
-            reference, description = image_data.strip().split("\n", 1)
+            if "\n" in image_data:
+                reference, description = image_data.split("\n", 1)
+            else:
+                msg = "Unable to get running image from reply"
+                self.logger.warning(msg, image_data=image_data)
+                reference = None
+                description = None
             self._image = RunningImage(
-                reference=reference or None,
-                description=description or None,
+                reference=reference.strip() if reference else None,
+                description=description.strip() if description else None,
             )
             if self.options.get_node:
                 # Our libraries currently spew warning messages when imported.