Display stderr and stdout when run_command fails

Throwing a `CalledProcessError` would hide the
messages when converted into a `Xenapi.Failure`
use a generic `Exception` with a properly formed
detail instead.

Signed-off-by: BenjiReis <[email protected]>

SOURCES/etc/xapi.d/plugins/raid.py

@@ -8,7 +8,7 @@
 import XenAPIPlugin
 
 sys.path.append('.')
-from xcpngutils import configure_logging, run_command, error_wrapped
+from xcpngutils import configure_logging, run_command, error_wrapped, ProcessException
 from xcpngutils.operationlocker import OperationLocker
 
 _LOGGER = configure_logging('raid')
@@ -21,7 +21,7 @@ def check_raid_pool(session, args):
     with OperationLocker():
         try:
             result = run_command(['mdadm', '--detail', device])
-        except subprocess.CalledProcessError:
+        except ProcessException:
             # No RAID
             return json.dumps({})
 

SOURCES/etc/xapi.d/plugins/xcpngutils/__init__.py

@@ -63,12 +63,22 @@ def log_unhandled_exception(origin, exception_type, exception_value,
     return logger
 
 
+class ProcessException(Exception):
+    def __init__(self, code, command, stderr, stdout):
+        self.returncode = code
+        self.command = command
+        self.stderr = stderr
+        self.stdout = stdout
+
+    def __str__(self):
+        return f"Command '{self.command}' failed with code: {self.returncode}"
+
 def run_command(command, check=True):
     process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     stdout, stderr = process.communicate()
     code = process.returncode
     if check and code != 0:
-        raise subprocess.CalledProcessError(code, command, None)
+        raise ProcessException(code, command, stderr, stdout)
     result = {'stdout': stdout, 'stderr': stderr, 'command': command, 'returncode': code}
     return result
 
@@ -123,6 +133,11 @@ def wrapper(*args, **kwds):
         except EnvironmentError as e:
             message = e.strerror if e.strerror is not None else str(e.args)
             raise XenAPIPlugin.Failure(str(e.errno), [message, str(e.filename), traceback.format_exc()])
+        except ProcessException as e:
+            raise_plugin_error(
+                e.returncode, str(e),
+                detail=f"stdout: '{e.stdout}', stderr: '{e.stderr}'", backtrace=traceback.format_exc()
+            )
         except Exception as e:
             raise_plugin_error('-1', str(e), backtrace=traceback.format_exc())
 

tests/test_raid.py

@@ -5,6 +5,7 @@
 import XenAPIPlugin
 
 from raid import check_raid_pool
+from xcpngutils import ProcessException
 
 MDADM_DETAIL_CMD = ['mdadm', '--detail', '/dev/md127']
 
@@ -61,7 +62,7 @@ def test_raid_error(self, run_command, fs):
         assert e.value.params[1] == 'Error!'
 
     def test_raid_missing(self, run_command, fs):
-        run_command.side_effect = subprocess.CalledProcessError(1, MDADM_DETAIL_CMD, None)
+        run_command.side_effect = ProcessException(1, MDADM_DETAIL_CMD, "stderr", "stdout")
         res = check_raid_pool(None, None)
         assert json.loads(res) == json.loads("{}")
         run_command.assert_called_once_with(MDADM_DETAIL_CMD)