feat: Add SlurmOpsError to slurm_ops

lib/charms/hpc_libs/v0/slurm_ops.py

@@ -91,6 +91,15 @@ def _on_install(self, _) -> None:
 _kebabize = re.compile(r"(?<=[a-z0-9])(?=[A-Z])")
 
 
+class SlurmOpsError(Exception):
+    """Exception raised when a slurm operation failed."""
+
+    @property
+    def message(self) -> str:
+        """Return message passed as argument to exception."""
+        return self.args[0]
+
+
 def format_key(key: str) -> str:
     """Format Slurm configuration keys from SlurmCASe into kebab case.
 
@@ -129,7 +138,7 @@ def _call(cmd: str, *args: str, stdin: Optional[str] = None) -> str:
     """Call a command with logging.
 
     Raises:
-        subprocess.CalledProcessError: Raised if the command fails.
+        SlurmOpsError: Raised if the command fails.
     """
     cmd = [cmd, *args]
     _logger.debug(f"Executing command {cmd}")
@@ -138,7 +147,7 @@ def _call(cmd: str, *args: str, stdin: Optional[str] = None) -> str:
     except subprocess.CalledProcessError as e:
         _logger.error(f"`{' '.join(cmd)}` failed")
         _logger.error(f"stderr: {e.stderr.decode()}")
-        raise
+        raise SlurmOpsError(f"command {cmd[0]} failed. Reason:\n{e.stderr.decode()}")
 
 
 def _snap(*args) -> str:

tests/unit/test_slurm_ops.py

@@ -64,7 +64,7 @@ def test_version(self, subcmd) -> None:
     def test_call_error(self, subcmd) -> None:
         """Test that `slurm_ops` propagates errors when a command fails."""
         subcmd.side_effect = subprocess.CalledProcessError(-1, cmd=[""], stderr=b"error")
-        with self.assertRaises(subprocess.CalledProcessError):
+        with self.assertRaises(slurm.SlurmOpsError):
             slurm.install()