fix(agent): detect absence in slurmrestd warnings

Detect absence of warnings key in slurmrestd reponses and emit warning
log instead of crashing.

fix #316

CHANGELOG.md

@@ -44,6 +44,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     interpreted by frontend and emit clear error message in logs (#321).
   - Detect responses from slurmrestd not formatted in JSON, translated into JSON
     error for frontend and emit clear error message in logs (#333).
+  - Detect absence of _warnings_ key in `slurmrestd` responses and emit warning
+    log instead of crashing (#316).
 - genjwt: fix portability to Python < 3.8 in debug message.
 - ldap-check: fix usage of `user_name_attribute` configuration parameter (#340).
 - frontend:

slurmweb/views/agent.py

@@ -92,7 +92,13 @@ def slurmrest(query, key, handle_errors=True):
                 error["description"],
                 error["source"],
             )
-    if len(result["warnings"]):
+    if "warnings" not in result:
+        logger.error(
+            "Unable to extract warnings from slurmrestd response to %s, unsupported "
+            "Slurm version?",
+            query,
+        )
+    elif len(result["warnings"]):
         logger.warning("slurmrestd query %s warnings: %s", query, result["warnings"])
     return result[key]