slapgrid: Adapt launching promise with SlapPopen

slapos/grid/slapgrid.py

@@ -59,7 +59,11 @@ from slapos import manager as slapmanager
 from slapos.slap.slap import NotFoundError
 from slapos.slap.slap import ServerError
 from slapos.slap.slap import COMPUTER_PARTITION_REQUEST_LIST_TEMPLATE_FILENAME
-from slapos.util import mkdir_p, chownDirectory, string_to_boolean, listifdir
+from slapos.util import (mkdir_p,
+                        chownDirectory,
+                        string_to_boolean,
+                        listifdir,
+                        unicode2str)
 from slapos.grid.exception import BuildoutFailedError
 from slapos.grid.SlapObject import Software, Partition
 from slapos.grid.svcbackend import (launchSupervisord,
@@ -68,7 +72,6 @@ from slapos.grid.svcbackend import (launchSupervisord,
                                     _getSupervisordSocketPath)
 from slapos.grid.utils import (md5digest,
                               dropPrivileges,
-                              killProcessTree,
                               SlapPopen,
                               updateFile)
 from slapos.grid.promise import PromiseLauncher, PromiseError
@@ -738,7 +741,6 @@ stderr_logfile_backups=1
         os.dup2(1, 2)
         dropPrivileges(uid, gid, logger=self.logger)
         os.dup2(err, 2)
-      try:
       process = SlapPopen(
         command,
         preexec_fn=preexec_fn,
@@ -749,17 +751,12 @@ stderr_logfile_backups=1
         logger=self.logger,
         timeout=timeout,
       )
-        stderr = process.stderr.read()
       if process.returncode == 2:
-          raise PromiseError(stderr)
+        raise PromiseError(unicode2str(process.error))
       elif process.returncode:
-          raise Exception(stderr)
-        elif stderr:
-          self.logger.warn('Unexpected promise runner output:\n%s', stderr)
-      except subprocess.TimeoutExpired:
-        killProcessTree(process.pid, self.logger)
-        # If this happens, it might be that the timeout margin is too small.
-        raise Exception('Promise runner timed out')
+        raise Exception(unicode2str(process.error))
+      elif process.error:
+        self.logger.warn('Unexpected promise runner output:\n%s', process.error)
 
     else:
       return PromiseLauncher(config=promise_config, logger=self.logger).run()