[feature] Use argo_nodeos_config --exec

Use the new argo_nodeos_config --exec feature in development.
Allow us to delegate fork+attach+exec to argo_nodeos_config, and
simplifying the create command as a result.

We use tornado.process to wrap this command, as we want to able to
stream stdout/stderr in the future.

This patch also misuse, the 'pid' field of the container namedtuple to
save the tornado.process.Subprocess object itself, so some functions
need to be adapted.

nrm/containers.py

@@ -6,7 +6,6 @@ import logging
 import os
 import signal
 from subprograms import ChrtClient, NodeOSClient, resources
-import sys
 
 logger = logging.getLogger('nrm')
 Container = namedtuple('Container', ['uuid', 'manifest', 'pid'])
@@ -60,32 +59,20 @@ class ContainerManager(object):
         self.nodeos.create(container_name, allocation)
         logger.info("created container %s", container_name)
 
-        newpid = os.fork()
-        logger.info("forked: new pid: %s", newpid)
-        if newpid == 0:
-            # move myself to that container
-            mypid = os.getpid()
-            self.nodeos.attach(container_name, mypid)
-            logger.info("child: attached to container %s", container_name)
-
-            # run my command
-            if hasattr(manifest.app.isolators, 'scheduler'):
-                sched = manifest.app.isolators.scheduler
-                argv = self.chrt.getwrappedcmd(sched)
-            else:
-                argv = []
-
-            argv.append(command)
-            argv.extend(args)
-            logger.debug("execvpe %r", argv)
-            os.execvpe(argv[0], argv, environ)
-            # should never happen
-            sys.exit(1)
+        # run my command
+        if hasattr(manifest.app.isolators, 'scheduler'):
+            sched = manifest.app.isolators.scheduler
+            argv = self.chrt.getwrappedcmd(sched)
         else:
-            c = Container(container_name, manifest, newpid)
-            self.pids[newpid] = c
-            self.containers[container_name] = c
-            return newpid
+            argv = []
+
+        argv.append(command)
+        argv.extend(args)
+        process = self.nodeos.execute(container_name, argv, environ)
+        c = Container(container_name, manifest, process)
+        self.pids[process.pid] = c
+        self.containers[container_name] = c
+        return process.pid
 
     def delete(self, uuid):
         """Delete a container and kill all related processes."""
@@ -93,7 +80,7 @@ class ContainerManager(object):
         self.resourcemanager.update(uuid)
         c = self.containers[uuid]
         del self.containers[uuid]
-        del self.pids[c.pid]
+        del self.pids[c.pid.pid]
 
     def kill(self, uuid):
         """Kill all the processes of a container."""
@@ -101,12 +88,11 @@ class ContainerManager(object):
             c = self.containers[uuid]
             logger.debug("killing %r:", c)
             try:
-                os.kill(c.pid, signal.SIGKILL)
+                c.pid.terminate()
             except OSError:
                 pass
 
     def list(self):
         """List the containers in the system."""
-        fields = ['uuid', 'pid']
-        ret = [c._asdict() for c in self.containers.values()]
-        return [{k: d[k] for k in fields} for d in ret]
+        return [{'uuid': c.uuid, 'pid': c.pid.pid} for c in
+                self.containers.values()]

nrm/subprograms.py

 """Various clients for system utilities."""
-import subprocess
 import collections
 import logging
 import xml.etree.ElementTree
+import tornado.process as process
+import subprocess
 
 logger = logging.getLogger('nrm')
 resources = collections.namedtuple("Resources", ["cpus", "mems"])
@@ -103,6 +104,22 @@ class NodeOSClient(object):
         stdout, stderr = p.communicate()
         logpopen(p, args, stdout, stderr)
 
+    def execute(self, name, argv, environ):
+        """Execute argv inside container."""
+        args = [self.prefix]
+        cmd = '--exec='
+        cmd += 'name:{0}'.format(name)
+        # argo_nodeos_config takes argv as 'arg0 arg1 ...' so we need to merge
+        # the arguments into a single list, with single quotes. We also need
+        # to escape spaces from arguments before.
+        argv = [s.replace(' ', r'\ ') for s in argv]
+        cmd += " argv:'"+" ".join(argv)+"'"
+        args.append(cmd)
+        return process.Subprocess(args, stdin=process.Subprocess.STREAM,
+                                  stdout=process.Subprocess.STREAM,
+                                  stderr=process.Subprocess.STREAM,
+                                  env=environ)
+
 
 class ChrtClient(object):