Added async functionality on backends

TODO.md

@@ -334,7 +334,7 @@ pip3 install https://github.com/APSL/django-mailer-2/archive/master.zip
 # all signals + accouns.register() services.register() on apps.py
 
 # if backend.async: don't join.
-# RELATED: domains.sync to ns3 make it async
+# RELATED: domains.sync to ns3 make it async backend rather than cron based ?
 
         from orchestra.contrib.tasks import task
         import time, sys
@@ -358,11 +358,8 @@ TODO mount the filesystem with "nosuid" option
 # autoiscover modules on app.ready()
 # uwse uwsgi cron: decorator or config cron = 59 2 -1 -1 -1 %(virtualenv)/bin/python manage.py runmyfunnytask
 
-# SecondaryMailServerBackend and check_origin signal
-try: import uwsgi to know its running uwsgi
 # avoid cron email errors when failing hard
 
-
 # mailboxes.address settings multiple local domains, not only one?
 # backend.context = self.get_context() or save(obj, context=None)
 
@@ -372,20 +369,11 @@ try: import uwsgi to know its running uwsgi
 
 # MERGE beats and inspect INSTALLED_APPS and get IS_ENABLED
 
-# make exceptions fot check origin shit
-
 # rename virtual_maps to virtual_alias_maps and remove virtual_alias_domains ?
 # virtdomains file is not ideal, prevent fake/error on domains there! and make sure this file is required!
 
-
 # Message last_retry auto_now doesn't work!
 
-
-# LOCK beat lockfile, all tasks (monitors, billing (or unique number will fuck the transaction?))
-
 # don't block on beat, and --report periodic tasks
 
 # Deprecate restart/start/stop services (do touch wsgi.py and fuck celery)
-
-
-# high perf apache sync, 

orchestra/contrib/orchestration/admin.py

@@ -25,10 +25,10 @@ STATE_COLORS = {
 
 class RouteAdmin(admin.ModelAdmin):
     list_display = (
-        'backend', 'host', 'match', 'display_model', 'display_actions', 'is_active'
+        'backend', 'host', 'match', 'display_model', 'display_actions', 'async', 'is_active'
     )
-    list_editable = ('host', 'match', 'is_active')
-    list_filter = ('host', 'is_active', 'backend')
+    list_editable = ('host', 'match', 'async', 'is_active')
+    list_filter = ('host', 'is_active', 'async', 'backend')
     ordering = ('backend',)
     
     BACKEND_HELP_TEXT = helpers.get_backends_help_text(ServiceBackend.get_backends())

orchestra/contrib/orchestration/backends.py

@@ -40,6 +40,7 @@ class ServiceBackend(plugins.Plugin, metaclass=ServiceMount):
     script_executable = '/bin/bash'
     function_method = methods.Python
     type = 'task'  # 'sync'
+    # Don't wait for the backend to finish before continuing with request/response
     ignore_fields = []
     actions = []
     default_route_match = 'True'
@@ -160,15 +161,22 @@ class ServiceBackend(plugins.Plugin, metaclass=ServiceMount):
         time = timezone.now().strftime("%h %d, %Y %I:%M:%S %Z")
         return "Generated by Orchestra at %s" % time
     
-    def execute(self, server, async=False):
+    def create_log(self, server, **kwargs):
         from .models import BackendLog
-        scripts = self.scripts
-        state = BackendLog.STARTED
-        run = bool(scripts) or (self.force_empty_action_execution or bool(self.content))
+        state = BackendLog.RECEIVED
+        run = bool(self.scripts) or (self.force_empty_action_execution or bool(self.content))
         if not run:
             state = BackendLog.NOTHING
         log = BackendLog.objects.create(backend=self.get_name(), state=state, server=server)
+        return log
+    
+    def execute(self, server, async=False, log=None):
+        from .models import BackendLog
+        if log is None:
+            log = self.create_log(server)
+        run = log.state != BackendLog.NOTHING
         if run:
+            scripts = self.scripts
             for method, commands in scripts:
                 method(log, server, commands, async)
                 if log.state != BackendLog.SUCCESS:

orchestra/contrib/orchestration/helpers.py

@@ -70,9 +70,18 @@ def send_report(method, args, log):
     mail_admins(subject, message, html_message=html_message)
 
 
+def get_backend_url(ids):
+    if len(ids) == 1:
+        return reverse('admin:orchestration_backendlog_change', args=ids)
+    elif len(ids) > 1:
+        url = reverse('admin:orchestration_backendlog_changelist')
+        return url + '?id__in=%s' % ','.join(map(str, ids))
+    return ''
+
 def message_user(request, logs):
-    total, successes = 0, 0
+    total, successes, async = 0, 0, 0
     ids = []
+    async_ids = []
     for log in logs:
         total += 1
         if log.state != log.EXCEPTION:
@@ -80,25 +89,42 @@ def message_user(request, logs):
             ids.append(log.pk)
         if log.state in (log.SUCCESS, log.NOTHING):
             successes += 1
-    errors = total-successes
-    if len(ids) == 1:
-        url = reverse('admin:orchestration_backendlog_change', args=ids)
-        href = '<a href="{}">backends</a>'.format(url)
-    elif len(ids) > 1:
-        url = reverse('admin:orchestration_backendlog_changelist')
-        url += '?id__in=%s' % ','.join(map(str, ids))
-        href = '<a href="{}">backends</a>'.format(url)
-    else:
-        href = ''
+        elif log.state in (log.RECEIVED, log.STARTED):
+            async += 1
+            async_ids.append(log.id)
+    errors = total-successes-async
+    url = get_backend_url(ids)
+    async_url = get_backend_url(async_ids)
+    async_msg = ''
+    if async:
+        async_msg = ungettext(
+            _('<a href="{async_url}">{async} backend</a> is running on the background'),
+            _('<a href="{async_url}">{async} backends</a> are running on the background'),
+            async)
     if errors:
         msg = ungettext(
-            _('{errors} out of {total} {href} has fail to execute.'),
-            _('{errors} out of {total} {href} have fail to execute.'),
+            _('<a href="{url}">{errors} out of {total} backend</a> has fail to execute'),
+            _('<a href="{url}">{errors} out of {total} backends</a> have fail to execute'),
             errors)
-        messages.error(request, mark_safe(msg.format(errors=errors, total=total, href=href)))
+        if async_msg:
+            msg += ', ' + str(async_msg)
+        msg = msg.format(errors=errors, async=async, async_url=async_url, total=total, url=url)
+        messages.error(request, mark_safe(msg + '.'))
+    elif successes:
+        if async_msg:
+            msg = ungettext(
+                _('<a href="{url}">{successes} out of {total} backend</a> has been executed'),
+                _('<a href="{url}">{successes} out of {total} backends</a> have been executed'),
+                successes)
+            msg += ', ' + str(async_msg)
         else:
             msg = ungettext(
-            _('{total} {href} has been executed.'),
-            _('{total} {href} have been executed.'),
+                _('<a href="{url}">{total} backend</a> has been executed'),
+                _('<a href="{url}">{total} backends</a> have been executed'),
                 total)
-        messages.success(request, mark_safe(msg.format(total=total, href=href)))
+        msg = msg.format(total=total, url=url, async_url=async_url, async=async, successes=successes)
+        messages.success(request, mark_safe(msg + '.'))
+    else:
+        msg = async_msg.format(url=url, async_url=async_url, async=async)
+        messages.success(request, mark_safe(msg + '.'))
+

orchestra/contrib/orchestration/manager.py

@@ -2,6 +2,7 @@ import logging
 import threading
 import traceback
 from collections import OrderedDict
+from functools import partial
 
 from django.core.mail import mail_admins
 
@@ -19,7 +20,7 @@ logger = logging.getLogger(__name__)
 router = import_class(settings.ORCHESTRATION_ROUTER)
 
 
-def as_task(execute):
+def as_task(execute, log, operations):
     def wrapper(*args, **kwargs):
         """ send report """
         # Tasks run on a separate transaction pool (thread), no need to temper with the transaction
@@ -33,12 +34,21 @@ def as_task(execute):
             logger.error(subject)
             logger.error(message)
             mail_admins(subject, message)
+            log.state = BackendLog.EXCEPTION
+            log.stderr = traceback.format_exc()
+            log.save(update_fields=('state', 'stderr'))
             # We don't propagate the exception further to avoid transaction rollback
-        else:
-            # Using the wrapper function as threader messenger for the execute output
-            # Absense of it will indicate a failure at this stage
-            wrapper.log = log
-            return log
+        finally:
+            # Store the operation
+            for operation in operations:
+                logger.info("Executed %s" % str(operation))
+                if operation.instance.pk:
+                    # Not all backends are called with objects saved on the database
+                    operation.store(log)
+            stdout = log.stdout.strip()
+            stdout and logger.debug('STDOUT %s', stdout)
+            stderr = log.stderr.strip()
+            stderr and logger.debug('STDERR %s', stderr)
     return wrapper
 
 
@@ -92,41 +102,31 @@ def execute(scripts, block=False, async=False):
         logger.info('Orchestration execution is dissabled by ORCHESTRATION_DISABLE_EXECUTION settings.')
         return []
     # Execute scripts on each server
-    threads = []
     executions = []
+    threads_to_join = []
+    logs = []
     for key, value in scripts.items():
         server, __ = key
         backend, operations = value
-        execute = as_task(backend.execute)
+        args = (server,)
+        kwargs = {
+            'async': async or server.async
+        }
+        log = backend.create_log(*args, **kwargs)
+        kwargs['log'] = log
+        task = as_task(backend.execute, log, operations)
         logger.debug('%s is going to be executed on %s' % (backend, server))
         if block:
             # Execute one backend at a time, no need for threads
-            execute(server, async=async)
+            task(*args, **kwargs)
         else:
-            execute = close_connection(execute)
-            thread = threading.Thread(target=execute, args=(server,), kwargs={'async': async})
+            task = close_connection(task)
+            thread = threading.Thread(target=task, args=args, kwargs=kwargs)
             thread.start()
-            threads.append(thread)
-        executions.append((execute, operations))
-    [ thread.join() for thread in threads ]
-    logs = []
-    # collect results
-    for execution, operations in executions:
-        # There is no log if an exception has been rised at the very end of the execution
-        if hasattr(execution, 'log'):
-            for operation in operations:
-                logger.info("Executed %s" % str(operation))
-                if operation.instance.pk:
-                    # Not all backends are called with objects saved on the database
-                    operation.store(execution.log)
-            stdout = execution.log.stdout.strip()
-            stdout and logger.debug('STDOUT %s', stdout)
-            stderr = execution.log.stderr.strip()
-            stderr and logger.debug('STDERR %s', stderr)
-            logs.append(execution.log)
-        else:
-            mocked_log = BackendLog(state=BackendLog.EXCEPTION)
-            logs.append(mocked_log)
+            if not server.async:
+                threads_to_join.append(thread)
+        logs.append(log)
+    [ thread.join() for thread in threads_to_join ]
     return logs
 
 

orchestra/contrib/orchestration/methods.py

@@ -33,8 +33,9 @@ def SSH(backend, log, server, cmds, async=False):
     digest = hashlib.md5(bscript).hexdigest()
     path = os.path.join(settings.ORCHESTRATION_TEMP_SCRIPT_DIR, digest)
     remote_path = "%s.remote" % path
+    log.state = log.STARTED
     log.script = '# %s\n%s' % (remote_path, script)
-    log.save(update_fields=['script'])
+    log.save(update_fields=('script', 'state'))
     if not cmds:
         return
     channel = None
@@ -133,8 +134,9 @@ def Python(backend, log, server, cmds, async=False):
     # TODO collect stdout?
     script = [ str(cmd.func.__name__) + str(cmd.args) for cmd in cmds ]
     script = json.dumps(script, indent=4).replace('"', '')
+    log.state = log.STARTED
     log.script = '\n'.join([log.script, script])
-    log.save(update_fields=['script'])
+    log.save(update_fields=('script', 'state'))
     try:
         for cmd in cmds:
             with CaptureStdout() as stdout:

orchestra/contrib/orchestration/migrations/0002_auto_20150506_1420.py

@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('orchestration', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='route',
+            name='async',
+            field=models.BooleanField(help_text='Whether or not block the request/response cycle waitting this backend to finish its execution.', default=False),
+        ),
+        migrations.AlterField(
+            model_name='backendlog',
+            name='state',
+            field=models.CharField(verbose_name='state', choices=[('RECEIVED', 'RECEIVED'), ('TIMEOUT', 'TIMEOUT'), ('STARTED', 'STARTED'), ('SUCCESS', 'SUCCESS'), ('FAILURE', 'FAILURE'), ('ERROR', 'ERROR'), ('ABORTED', 'ABORTED'), ('REVOKED', 'REVOKED'), ('NOTHING', 'NOTHING')], default='RECEIVED', max_length=16),
+        ),
+        migrations.AlterField(
+            model_name='backendlog',
+            name='stderr',
+            field=models.TextField(verbose_name='stderr'),
+        ),
+        migrations.AlterField(
+            model_name='route',
+            name='backend',
+            field=models.CharField(choices=[('Apache2Traffic', '[M] Apache 2 Traffic'), ('DovecotMaildirDisk', '[M] Dovecot Maildir size'), ('Exim4Traffic', '[M] Exim4 traffic'), ('MailmanSubscribers', '[M] Mailman subscribers'), ('MailmanTraffic', '[M] Mailman traffic'), ('MysqlDisk', '[M] MySQL disk'), ('OpenVZTraffic', '[M] OpenVZTraffic'), ('PostfixMailscannerTraffic', '[M] Postfix-Mailscanner traffic'), ('UNIXUserDisk', '[M] UNIX user disk'), ('VsFTPdTraffic', '[M] VsFTPd traffic'), ('Apache2Backend', '[S] Apache 2'), ('BSCWBackend', '[S] BSCW SaaS'), ('Bind9MasterDomainBackend', '[S] Bind9 master domain'), ('Bind9SlaveDomainBackend', '[S] Bind9 slave domain'), ('DokuWikiMuBackend', '[S] DokuWiki multisite'), ('DovecotPostfixPasswdVirtualUserBackend', '[S] Dovecot-Postfix virtualuser'), ('DrupalMuBackend', '[S] Drupal multisite'), ('GitLabSaaSBackend', '[S] GitLab SaaS'), ('AutoresponseBackend', '[S] Mail autoresponse'), ('MailmanBackend', '[S] Mailman'), ('MailmanVirtualDomainBackend', '[S] Mailman virtdomain-only'), ('MySQLBackend', '[S] MySQL database'), ('MySQLUserBackend', '[S] MySQL user'), ('PHPBackend', '[S] PHP FPM/FCGID'), ('PostfixAddressBackend', '[S] Postfix address'), ('PostfixAddressVirtualDomainBackend', '[S] Postfix address virtdomain-only'), ('uWSGIPythonBackend', '[S] Python uWSGI'), ('StaticBackend', '[S] Static'), ('SymbolicLinkBackend', '[S] Symbolic link webapp'), ('SyncBind9MasterDomainBackend', '[S] Sync Bind9 master domain'), ('SyncBind9SlaveDomainBackend', '[S] Sync Bind9 slave domain'), ('UNIXUserMaildirBackend', '[S] UNIX maildir user'), ('UNIXUserBackend', '[S] UNIX user'), ('WebalizerAppBackend', '[S] Webalizer App'), ('WebalizerBackend', '[S] Webalizer Content'), ('WordPressBackend', '[S] Wordpress'), ('WordpressMuBackend', '[S] Wordpress multisite'), ('PhpListSaaSBackend', '[S] phpList SaaS')], verbose_name='backend', max_length=256),
+        ),
+    ]

orchestra/contrib/orchestration/models.py

@@ -133,7 +133,9 @@ class Route(models.Model):
     match = models.CharField(_("match"), max_length=256, blank=True, default='True',
         help_text=_("Python expression used for selecting the targe host, "
                     "<em>instance</em> referes to the current object."))
-#    async = models.BooleanField(default=False)
+    async = models.BooleanField(default=False,
+        help_text=_("Whether or not block the request/response cycle waitting this backend to "
+                    "finish its execution."))
 #    method = models.CharField(_("method"), max_lenght=32, choices=method_choices,
 #            default=MethodBackend.get_default())
     is_active = models.BooleanField(_("active"), default=True)
@@ -148,6 +150,7 @@ class Route(models.Model):
     def backend_class(self):
         return ServiceBackend.get_backend(self.backend)
     
+    # TODO rename to get_hosts
     @classmethod
     def get_servers(cls, operation, **kwargs):
         cache = kwargs.get('cache', {})
@@ -169,6 +172,7 @@ class Route(models.Model):
         else:
             for route in routes:
                 if route.matches(operation.instance):
+                    route.host.async = route.async
                     servers.append(route.host)
         return servers
     

orchestra/contrib/resources/tasks.py

@@ -8,7 +8,7 @@ from .backends import ServiceMonitor
 
 @task(name='resources.Monitor')
 def monitor(resource_id, ids=None, async=True):
-    with LockFile('/dev/shm/resources.monitor.lock', expire=60*60):
+    with LockFile('/dev/shm/resources.monitor-%i.lock' % resource_id, expire=60*60):
         from .models import ResourceData, Resource
         resource = Resource.objects.get(pk=resource_id)
         resource_model = resource.content_type.model_class()

orchestra/contrib/webapps/backends/__init__.py

@@ -28,9 +28,15 @@ class WebAppServiceMixin(object):
     def set_under_construction(self, context):
         if context['under_construction_path']:
             self.append(textwrap.dedent("""\
-                if [[ $CREATED == 1 ]]; then
+                if [[ $CREATED == 1 && ! $(ls -A %(app_path)s) ]]; then
+                    {
+                        # Wait for other backends to do their thing or cp under construction
+                        sleep 1
+                        if [[ ! $(ls -A %(app_path)s) ]]; then
                             cp -r %(under_construction_path)s %(app_path)s
                             chown -R %(user)s:%(group)s %(app_path)s
+                        fi
+                    } &
                 fi""") % context
             )
     

orchestra/contrib/webapps/backends/php.py

@@ -34,13 +34,13 @@ class PHPBackend(WebAppServiceMixin, ServiceController):
     def save(self, webapp):
         context = self.get_context(webapp)
         self.create_webapp_dir(context)
-        self.set_under_construction(context)
         if webapp.type_instance.is_fpm:
             self.save_fpm(webapp, context)
             self.delete_fcgid(webapp, context)
         elif webapp.type_instance.is_fcgid:
             self.save_fcgid(webapp, context)
             self.delete_fpm(webapp, context)
+        self.set_under_construction(context)
     
     def save_fpm(self, webapp, context):
         self.append(textwrap.dedent("""\
@@ -108,36 +108,38 @@ class PHPBackend(WebAppServiceMixin, ServiceController):
     def prepare(self):
         super(PHPBackend, self).prepare()
         # Coordinate apache restart with php backend in order not to overdo it
-        self.append('echo "PHPBackend" >> /dev/shm/restart.apache2')
+        self.append(textwrap.dedent("""\
+            backend="PHPBackend"
+            echo "$backend" >> /dev/shm/restart.apache2
+            """)
+        )
     
     def commit(self):
         self.append(textwrap.dedent("""
             if [[ $UPDATED_FPM -eq 1 ]]; then
                 service php5-fpm reload
             fi
-            # Coordinate apache restart with Apache2Backend
-            restart=0
-            backend='PHPBackend'
+            
+            # Coordinate Apache restart with other concurrent backends (i.e. Apache2Backend)
+            is_last=0
             mv /dev/shm/restart.apache2 /dev/shm/restart.apache2.locked || {
-                sleep 0.1
+                sleep 0.2
                 mv /dev/shm/restart.apache2 /dev/shm/restart.apache2.locked
             }
-            state="$(grep -v $backend /dev/shm/restart.apache2.locked)" || restart=1
+            state="$(grep -v "$backend" /dev/shm/restart.apache2.locked)" || is_last=1
+            if [[ $is_last -eq 1 ]]; then
+                if [[ $UPDATED_APACHE -eq 1 || "$state" =~ .*RESTART$ ]]; then
+                    service apache2 status && service apache2 reload || service apache2 start
+                fi
+                rm /dev/shm/restart.apache2.locked
+            else
                 echo -n "$state" > /dev/shm/restart.apache2.locked
                 if [[ $UPDATED_APACHE -eq 1 ]]; then
-                if [[ $restart == 1 ]]; then
-                    service apache2 status && service apache2 reload || service apache2 start
-                    rm /dev/shm/restart.apache2.locked
-                else
                     echo "$backend RESTART" >> /dev/shm/restart.apache2.locked
+                fi
                 mv /dev/shm/restart.apache2.locked /dev/shm/restart.apache2
             fi
-            elif [[ "$state" =~ .*RESTART$ ]]; then
-                rm /dev/shm/restart.apache2.locked
-                service apache2 status && service apache2 reload || service apache2 start
-            else
-                mv /dev/shm/restart.apache2.locked /dev/shm/restart.apache2
-            fi
+            # End of coordination
             """)
         )
         super(PHPBackend, self).commit()

orchestra/contrib/websites/backends/apache.py

@@ -132,34 +132,36 @@ class Apache2Backend(ServiceController):
     def prepare(self):
         super(Apache2Backend, self).prepare()
         # Coordinate apache restart with php backend in order not to overdo it
-        self.append('echo "Apache2Backend" >> /dev/shm/restart.apache2')
+        self.append(textwrap.dedent("""\
+            backend="Apache2Backend"
+            echo "$backend" >> /dev/shm/restart.apache2
+            """)
+        )
     
     def commit(self):
         """ reload Apache2 if necessary """
-        self.append(textwrap.dedent("""\
-            # Coordinate apache restart with Apache2Backend
-            restart=0
-            backend='Apache2Backend'
+        self.append(textwrap.dedent("""
+            # Coordinate Apache restart with other concurrent backends (i.e. Apache2Backend)
+            is_last=0
             mv /dev/shm/restart.apache2 /dev/shm/restart.apache2.locked || {
-                sleep 0.1
+                sleep 0.2
                 mv /dev/shm/restart.apache2 /dev/shm/restart.apache2.locked
             }
-            state="$(grep -v $backend /dev/shm/restart.apache2.locked)" || restart=1
+            state="$(grep -v "$backend" /dev/shm/restart.apache2.locked)" || is_last=1
+            if [[ $is_last -eq 1 ]]; then
+                if [[ $UPDATED_APACHE -eq 1 || "$state" =~ .*RESTART$ ]]; then
+                    service apache2 status && service apache2 reload || service apache2 start
+                fi
+                rm /dev/shm/restart.apache2.locked
+            else
                 echo -n "$state" > /dev/shm/restart.apache2.locked
                 if [[ $UPDATED_APACHE -eq 1 ]]; then
-                if [[ $restart == 1 ]]; then
-                    service apache2 status && service apache2 reload || service apache2 start
-                    rm /dev/shm/restart.apache2.locked
-                else
                     echo "$backend RESTART" >> /dev/shm/restart.apache2.locked
+                fi
                 mv /dev/shm/restart.apache2.locked /dev/shm/restart.apache2
             fi
-            elif [[ "$state" =~ .*RESTART$ ]]; then
-                rm /dev/shm/restart.apache2.locked
-                service apache2 status && service apache2 reload || service apache2 start
-            else
-                mv /dev/shm/restart.apache2.locked /dev/shm/restart.apache2
-            fi""")
+            # End of coordination
+            """)
         )
         super(Apache2Backend, self).commit()
     

orchestra/management/commands/setupcronbeat.py

@@ -19,8 +19,8 @@ class Command(BaseCommand):
         content = run('crontab -l || true').stdout.decode('utf8')
         if 'orchestra-beat' not in content:
             if context['venv']:
-                content += "* * * * * . %(venv)s/bin/activate && %(orchestra_beat)s %(site_dir)s/manage.py; deactivate" % context
+                content += "\n* * * * * . %(venv)s/bin/activate && %(orchestra_beat)s %(site_dir)s/manage.py; deactivate" % context
             else:
-                content += "* * * * * %(orchestra_beat)s %(site_dir)s/manage.py" % context
+                content += "\n* * * * * %(orchestra_beat)s %(site_dir)s/manage.py" % context
             context['content'] = content
-            run("echo '%(content)s' | crontab" % context, display=True)
+            run("cat << EOF | crontab\n%(content)s\nEOF" % context, display=True)

orchestra/utils/db.py

@@ -7,7 +7,7 @@ def close_connection(execute):
         try:
             log = execute(*args, **kwargs)
         except Exception as e:
-            pass
+            raise
         else:
             wrapper.log = log
         finally:

orchestra/utils/sys.py

@@ -124,7 +124,7 @@ def join(iterator, display=False, silent=False, error_codes=[0]):
         if display:
             sys.stderr.write("\n\033[1;31mCommandError: %s %s\033[m\n" % (msg, err))
         if not silent:
-            raise CommandError("%s %s %s" % (msg, err, out))
+            raise CommandError("%s %s" % (msg, err))
     
     out.succeeded = not out.failed
     return out
@@ -158,6 +158,13 @@ def get_default_celeryd_username():
     return user
 
 
+def touch(fname, mode=0o666, dir_fd=None, **kwargs):
+    flags = os.O_CREAT | os.O_APPEND
+    with os.fdopen(os.open(fname, flags=flags, mode=mode, dir_fd=dir_fd)) as f:
+        os.utime(f.fileno() if os.utime in os.supports_fd else fname,
+            dir_fd=None if os.supports_fd else dir_fd, **kwargs)
+
+
 class LockFile(object):
     """ File-based lock mechanism used for preventing concurrency problems """
     def __init__(self, lockfile, expire=5*60, unlocked=False):