Merge lp:~cprov/uci-engine/ticket-conflicts into lp:uci-engine

[Celso Providelo]

Implement and expose Subticket.conflicts.

Implement and expose Subticket.conflicts.

Each subticket may point to currently active tickets including SPUs/MPs for the same source package.

The conflicting tickets are referred by subtickets in order to give the user a better understanding of which *part* (subticket) of his task (ticket) is likely to result in conflicts when landing.

Full conflicting context will be provided during the landing (publishing) step.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:794
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1419/
Executed test runs:

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Francis Ginther (fginther)]

Just one question on excluding NEW tickets. Otherwise this looks good and tests look reasonable.

review: Needs Information

[Celso Providelo (cprov)]

On Fri, Sep 19, 2014 at 5:49 PM, Francis Ginther
<email address hidden> wrote:
> Review: Needs Information
>
> Just one question on excluding NEW tickets. Otherwise this looks good and tests look reasonable.

Thank you.

> What's the reason for not considering 'NEW' tickets as conflicts? Not saying it's wrong, I'm just not seeing the scenario around this.

NEW tickets are not considered by the Lander and I believe it was
implemented this way to cope with the multi-step ticket creation
process we currently have. Recently I've also extended the CLI to
optionally not queue the ticket after creation (create_ticket ... -w).
The intended scenario here is to allow users to register WIP tickets
in a same way we register WIP MPs (to inform/share in-progress tasks).

In the conflicting scenario, NEW (WIP) tickets will list existing
conflict but won't be considered a conflict for other active tickets.
The same behaviour might apply to other static relation/analysis we
can perform on the TS environment.

Does it make more sense ?

--
Celso Providelo
<email address hidden>

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:795
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1420/
Executed test runs:

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review: Approve (continuous-integration)

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:796
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1421/
Executed test runs:

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1421/rebuild

review: Approve (continuous-integration)

[Francis Ginther (fginther)]

Approve.

review: Approve

[Francis Ginther (fginther)]

> On Fri, Sep 19, 2014 at 5:49 PM, Francis Ginther
> <email address hidden> wrote:
> > Review: Needs Information
> >
> > Just one question on excluding NEW tickets. Otherwise this looks good and
> tests look reasonable.
>
> Thank you.
>
> > What's the reason for not considering 'NEW' tickets as conflicts? Not saying
> it's wrong, I'm just not seeing the scenario around this.
>
> NEW tickets are not considered by the Lander and I believe it was
> implemented this way to cope with the multi-step ticket creation
> process we currently have. Recently I've also extended the CLI to
> optionally not queue the ticket after creation (create_ticket ... -w).
> The intended scenario here is to allow users to register WIP tickets
> in a same way we register WIP MPs (to inform/share in-progress tasks).
>
> In the conflicting scenario, NEW (WIP) tickets will list existing
> conflict but won't be considered a conflict for other active tickets.
> The same behaviour might apply to other static relation/analysis we
> can perform on the TS environment.
>
> Does it make more sense ?

Yes, this approach makes sense.

[Ubuntu CI Bot (uci-bot)]

The attempt to merge lp:~cprov/uci-engine/ticket-conflicts into lp:uci-engine failed. Below is the output from the failed tests.

Running cm...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
uploading webui-content.tgz to swift
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
Checking juju status
Private PPAs: disabled
Preparing local branch upload...
Uploading local branch, fingerprint b2ef646eb9e6fe5f2ac158ce76894a39e74a9fb3
Building charm: lander
Building charm: wsgi-app
Building charm: rabbitmq-worker
Building charm: webui
Building charm: key-secret-subordinate
Building charm: system-image-server
Building charm: chroot-builder
Installing keys from bzr+ssh://bazaar.launchpad.net/~ci-engineering-private/+junk/ci-airline-dev-keys/
Running juju-deployer -v -c /tmp/tmpAqmn35/deployer/branch-source-builder.yaml -c /tmp/tmpAqmn35/deployer/britney-proxy.yaml -c /tmp/tmpAqmn35/deployer/gatekeeper.yaml -c /tmp/tmpAqmn35/deployer/image-builder.yaml -c /tmp/tmpAqmn35/deployer/lander.yaml -c /tmp/tmpAqmn35/deployer/nf-stats-service.yaml -c /tmp/tmpAqmn35/deployer/ppa-creator.yaml -c /tmp/tmpAqmn35/deployer/publisher.yaml -c /tmp/tmpAqmn35/deployer/relations.yaml -c /tmp/tmpAqmn35/deployer/test-runner.yaml -c /tmp/tmpAqmn35/deployer/ticket-system.yaml -c /tmp/tmpAqmn35/deployer/validator.yaml -c /tmp/tmpAqmn35/deployer/webui.yaml ci-airline
Tests running...
ci-utils.ci_utils.tests.test_amqp.TestAMQP.testConnectFailed ... OK (0.001 secs)
ci-utils.ci_utils.tests.test_amqp.TestAMQP.testProcessQueue ... OK (0.002 secs)
ci-utils.ci_utils.tests.test_amqp.TestAMQP.testRunForever ... OK (0.101 secs)
ci-utils.ci_utils.tests.test_amqp.TestAMQP.testSent ... OK (0.003 secs)
ci-utils.ci_utils.tests.test_amqp.TestProgressTrigger.testProgress ... OK (0.001 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testCancel ... OK (0.107 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testNoQueue ... OK (0.002 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testNoTicket ... OK (0.003 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testOnMessageCalledProcessError ... OK (0.003 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testOnMessageFail ... OK (0.003 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testOnMessageKilled ... OK (0.002 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testOnMessageSimple ... OK (0.002 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testOnMessageUnexpected ... OK (0.002 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestAMQPWorker.testSaveLastRun ... OK (0.003 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestTimer.testCBRuns ... OK (0.020 secs)
ci-utils.ci_utils.tests.test_amqp_worker.TestTimer.testCanCancel ... OK (0.001 secs)
ci-utils.ci_utils.tests.test_data_store.TestDataStoreConfig.test_invalid_auth_config ... OK (0.000 secs)
ci-utils.ci_utils.tests.test_data_store.TestDataStoreConfig.test_valid_auth_config ... OK (0.000 secs)
ci-utils.ci_utils.tests.test_data_store.TestDataStoreFileName.test_get_file_nam...

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:798
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1452/
Executed test runs:

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1452/rebuild

review: Approve (continuous-integration)

[Ubuntu CI Bot (uci-bot)]

The attempt to merge lp:~cprov/uci-engine/ticket-conflicts into lp:uci-engine failed. Below is the output from the failed tests.

Running cm...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
uploading webui-content.tgz to swift
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
2014-09-24 13:11:07 INFO juju.cmd supercommand.go:37 running jujud [1.20.7.1-precise-amd64 gc]
2014-09-24 13:11:07 DEBUG juju.agent agent.go:377 read agent config, format "1.18"
2014-09-24 13:11:07 INFO juju.jujud unit.go:78 unit agent unit-ci-airline-ts-django-0 start (1.20.7.1-precise-amd64 [gc])
2014-09-24 13:11:07 INFO juju.worker runner.go:260 start "api"
2014-09-24 13:11:07 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:11:07 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:11:07 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:11:07 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:11:16 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:11:16 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:11:16 INFO juju.worker runner.go:260 start "upgrader"
2014-09-24 13:11:16 INFO juju.worker runner.go:260 start "logger"
2014-09-24 13:11:16 DEBUG juju.worker.logger logger.go:35 initial log config: "<root>=DEBUG"
2014-09-24 13:11:16 INFO juju.worker runner.go:260 start "uniter"
2014-09-24 13:11:16 DEBUG juju.worker.logger logger.go:60 logger setup
2014-09-24 13:11:16 INFO juju.worker runner.go:260 start "apiaddressupdater"
2014-09-24 13:11:16 INFO juju.worker runner.go:260 start "rsyslog"
2014-09-24 13:11:16 DEBUG juju.worker.rsyslog worker.go:75 starting rsyslog worker mode 1 for "unit-ci-airline-ts-django-0" "tarmac-local"
2014-09-24 13:11:16 DEBUG juju.worker.logger logger.go:45 reconfiguring logging from "<root>=DEBUG" to "<root>=WARNING;unit=DEBUG"
2014-09-24 13:11:34 INFO juju-log Making dir /srv/ci-airline-ts-django/nagios www-data:www-data 755
2014-09-24 13:11:34 INFO juju-log installing apt packages...
2014-09-24 13:11:38 INFO install gpg: keyring `/tmp/tmpycVR_E/secring.gpg' created
2014-09-24 13:11:38 INFO install gpg: keyring `/tmp/tmpycVR_E/pubring.gpg' created
2014-09-24 13:11:38 INFO install gpg: requesting key 6A8DFC40 from hkp server keyserver.ubuntu.com
2014-09-24 13:11:38 INFO install gpg: /tmp/tmpycVR_E/trustdb.gpg: trustdb created
2014-09-24 13:11:38 INFO install gpg: key 6A8DFC40: public key "Launchpad PPA for Canonical CI Engineering" imported
2014-09-24 13:11:38 INFO install gpg: Total number processed: 1
2014-09-24 13:11:38 INFO install gpg: imported: 1 (RSA: 1)
2014-09-24 13:11:39 INFO install OK
2014-09-24 13:11:42 INFO install Get:1 http://ubuntu-cloud.archive.canonical.com precise-updates/cloud-tools Release.gpg [543 B]
2014-09-24 13:11:42 INFO install Hit http://archive.ubuntu.com precise Release.gpg
2014-09-24 13:11:42 INFO...

[Ubuntu CI Bot (uci-bot)]

The attempt to merge lp:~cprov/uci-engine/ticket-conflicts into lp:uci-engine failed. Below is the output from the failed tests.

Running cm...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
uploading webui-content.tgz to swift
Updating source dependencies...
Updating source dependencies...
Updating source dependencies...
2014-09-24 13:40:53 INFO juju.cmd supercommand.go:37 running jujud [1.20.7.1-precise-amd64 gc]
2014-09-24 13:40:53 DEBUG juju.agent agent.go:377 read agent config, format "1.18"
2014-09-24 13:40:53 INFO juju.jujud unit.go:78 unit agent unit-ci-airline-ts-django-0 start (1.20.7.1-precise-amd64 [gc])
2014-09-24 13:40:53 INFO juju.worker runner.go:260 start "api"
2014-09-24 13:40:53 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:40:53 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:40:53 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:40:53 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:40:54 INFO juju.state.api apiclient.go:242 dialing "wss://10.0.3.1:17070/"
2014-09-24 13:40:54 INFO juju.state.api apiclient.go:176 connection established to "wss://10.0.3.1:17070/"
2014-09-24 13:40:54 INFO juju.worker runner.go:260 start "upgrader"
2014-09-24 13:40:54 INFO juju.worker runner.go:260 start "logger"
2014-09-24 13:40:54 DEBUG juju.worker.logger logger.go:35 initial log config: "<root>=DEBUG"
2014-09-24 13:40:54 INFO juju.worker runner.go:260 start "uniter"
2014-09-24 13:40:54 DEBUG juju.worker.logger logger.go:60 logger setup
2014-09-24 13:40:54 INFO juju.worker runner.go:260 start "apiaddressupdater"
2014-09-24 13:40:54 INFO juju.worker runner.go:260 start "rsyslog"
2014-09-24 13:40:54 DEBUG juju.worker.rsyslog worker.go:75 starting rsyslog worker mode 1 for "unit-ci-airline-ts-django-0" "tarmac-local"
2014-09-24 13:40:54 DEBUG juju.worker.logger logger.go:45 reconfiguring logging from "<root>=DEBUG" to "<root>=WARNING;unit=DEBUG"
2014-09-24 13:41:03 INFO juju-log Making dir /srv/ci-airline-ts-django/nagios www-data:www-data 755
2014-09-24 13:41:03 INFO juju-log installing apt packages...
2014-09-24 13:41:08 INFO install gpg: keyring `/tmp/tmpfS7NKC/secring.gpg' created
2014-09-24 13:41:08 INFO install gpg: keyring `/tmp/tmpfS7NKC/pubring.gpg' created
2014-09-24 13:41:08 INFO install gpg: requesting key 6A8DFC40 from hkp server keyserver.ubuntu.com
2014-09-24 13:41:08 INFO install gpg: /tmp/tmpfS7NKC/trustdb.gpg: trustdb created
2014-09-24 13:41:08 INFO install gpg: key 6A8DFC40: public key "Launchpad PPA for Canonical CI Engineering" imported
2014-09-24 13:41:08 INFO install gpg: Total number processed: 1
2014-09-24 13:41:08 INFO install gpg: imported: 1 (RSA: 1)
2014-09-24 13:41:08 INFO install OK
2014-09-24 13:41:09 INFO install Hit http://archive.ubuntu.com precise Release.gpg
2014-09-24 13:41:09 INFO install Get:1 http://ppa.launchpad.net precise Release.gpg [316 B]
2014-09-24 13:41:09 INFO install Get:2 http://ubuntu-cloud.ar...

[lp:~cprov/uci-engine/ticket-conflicts]

799. By Celso Providelo on 2014-09-24

merge trunk

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:799
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1459/
Executed test runs:

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/uci-engine-ci/1459/rebuild

review: Approve (continuous-integration)

=== modified file 'ticket_system/ticket/api.py'
--- ticket_system/ticket/api.py	2014-08-29 18:28:56 +0000
+++ ticket_system/ticket/api.py	2014-09-24 17:47:41 +0000
@@ -154,22 +154,23 @@
             return ''
 
 
-class SubTicketTranslatedResource(ModelResource):
-
-    def dehydrate_current_workflow_step(self, bundle):
-        return get_enum_title(bundle.data["current_workflow_step"],
-                              SubTicketWorkflowStep)
-
-    def dehydrate_status(self, bundle):
-        return get_enum_title(bundle.data["status"],
-                              SubTicketWorkflowStepStatus)
+class SourcePackageUploadResource(ModelResource):
+
+    sourcepackage = fields.ToOneField(
+        SourcePackageResource, 'sourcepackage', full=True)
+
+    class Meta:
+        queryset = SourcePackageUpload.objects.all()
+        allowed_methods = ['get', 'post']
+        authorization = Authorization()
+        resource_name = 'spu'
 
 
 class TicketResource(TicketTranslatedResource):
 
     class Meta:
         # XXX cprov 20140829: 'private' should only be considered via
-        # authorization mechnisms, not on the local resource queryset.
+        # authorization mechanisms, not on the local resource queryset.
         queryset = Ticket.objects.filter(private=False)
         allowed_methods = ['get', 'post', 'patch']
         authorization = Authorization()
@@ -179,22 +180,26 @@
         paginator_class = PageNumberPaginator
 
 
-class SourcePackageUploadResource(ModelResource):
-    sourcepackage = fields.ToOneField(SourcePackageResource, 'sourcepackage',
-                                      full=True)
-
-    class Meta:
-        queryset = SourcePackageUpload.objects.all()
-        allowed_methods = ['get', 'post']
-        authorization = Authorization()
-        resource_name = 'spu'
+class SubTicketTranslatedResource(ModelResource):
+
+    def dehydrate_current_workflow_step(self, bundle):
+        return get_enum_title(bundle.data["current_workflow_step"],
+                              SubTicketWorkflowStep)
+
+    def dehydrate_status(self, bundle):
+        return get_enum_title(bundle.data["status"],
+                              SubTicketWorkflowStepStatus)
+
+    source_package_upload = fields.ToOneField(
+        SourcePackageUploadResource, 'source_package_upload', full=True)
+
+    conflicts = fields.ToManyField(
+        TicketResource, 'conflicts', readonly=True, null=True, full=False)
 
 
 class SubTicketResource(SubTicketTranslatedResource):
+
     ticket = fields.ToOneField(TicketResource, 'ticket', full=True)
-    source_package_upload = fields.ToOneField(SourcePackageUploadResource,
-                                              'source_package_upload',
-                                              full=True)
 
     class Meta:
         queryset = SubTicket.objects.all()
@@ -216,8 +221,9 @@
 
 
 class SubTicketArtifactResource(ModelResource):
-    subticket = fields.ToOneField(SubTicketResource, 'subticket', null=True,
-                                  full=True)
+
+    subticket = fields.ToOneField(SubTicketResource, 'subticket',
+                                  readonly=True, null=True, full=True)
 
     class Meta:
         queryset = SubTicketArtifact.objects.all()
@@ -240,9 +246,7 @@
 
 
 class FullSubTicketResource(SubTicketTranslatedResource):
-    source_package_upload = fields.ToOneField(SourcePackageUploadResource,
-                                              'source_package_upload',
-                                              full=True)
+
     artifact = fields.ToManyField(FullSubTicketArtifactResource,
                                   'subticketartifact_set', full=True)
 
@@ -252,6 +256,7 @@
 
 
 class FullTicketResource(TicketTranslatedResource):
+
     subticket = fields.ToManyField(FullSubTicketResource, 'subticket_set',
                                    full=True)
     artifact = fields.ToManyField(FullTicketArtifactResource,

=== modified file 'ticket_system/ticket/models.py'
--- ticket_system/ticket/models.py	2014-09-09 17:25:59 +0000
+++ ticket_system/ticket/models.py	2014-09-24 17:47:41 +0000
@@ -232,6 +232,7 @@
 class SubTicket(models.Model):
     class Meta:
         db_table = 'subticket'
+        ordering = ['id']
 
     current_workflow_step = models.IntegerField(
         choices=_choices(SubTicketWorkflowStep), max_length=4096,
@@ -246,6 +247,34 @@
     merge_proposal = models.ForeignKey(MergeProposal, null=True, blank=True,
                                        default=None)
 
+    @property
+    def conflicts(self):
+        """Return `Ticket`s that conflict with this subticket task.
+
+        A ticket is considered a conflict if it contains a `SubTicket`
+        with a `SourcePackageUpload` or a `MergeProposal` for the same
+        'name' of this `SubTicket`. I.e. conflicts may happen between
+        a MP and a SPU.
+
+        Only *active* (not NEW|FAILED|COMPLETED) tickets are considered
+        for conflicts.
+        """
+        if self.merge_proposal is not None:
+            sp = self.merge_proposal.sourcepackage
+        else:
+            sp = self.source_package_upload.sourcepackage
+
+        conflicting_tickets = Ticket.objects.filter(
+            models.Q(subticket__merge_proposal__sourcepackage=sp)
+            | models.Q(subticket__source_package_upload__sourcepackage=sp),
+            ~models.Q(pk=self.ticket.pk),
+            ~models.Q(status=TicketWorkflowStepStatus.FAILED),
+            current_workflow_step__range=(
+                TicketWorkflowStep.QUEUED, TicketWorkflowStep.PKG_PUBLISHING),
+        )
+
+        return conflicting_tickets
+
     def save(self, *args, **kwargs):
         if self.source_package_upload and self.merge_proposal:
             raise IntegrityError("Subtickets only accept a source package "

=== modified file 'ticket_system/ticket/tests/test_full_read_api.py'
--- ticket_system/ticket/tests/test_full_read_api.py	2014-09-08 13:32:31 +0000
+++ ticket_system/ticket/tests/test_full_read_api.py	2014-09-24 17:47:41 +0000
@@ -98,6 +98,7 @@
                     u'resource_uri':
                     u'/api/v1/spu/{0}/'.format(self.spu.pk)},
                 u'id': self.subticket.pk,
+                u'conflicts': [],
                 u'resource_uri': u'/api/v1/fullsubticket/{0}/'.format(
                     self.subticket.pk)}],
             u'bug_id': self.ticket.bug_id,
@@ -168,6 +169,7 @@
                 u'resource_uri':
                 u'/api/v1/spu/{0}/'.format(self.spu.pk)},
             u'id': self.subticket.pk,
+            u'conflicts': [],
             u'resource_uri': u'/api/v1/fullsubticket/{0}/'.format(
                 self.subticket.pk),
         })

=== modified file 'ticket_system/ticket/tests/test_models.py'
--- ticket_system/ticket/tests/test_models.py	2014-08-27 11:59:06 +0000
+++ ticket_system/ticket/tests/test_models.py	2014-09-24 17:47:41 +0000
@@ -44,7 +44,7 @@
     return sourcepackage
 
 
-def create_sourcepackageupload(sourcepackage='my-package', version='1.1'):
+def create_sourcepackageupload(sourcepackage, version='1.1'):
     spu = SourcePackageUpload()
     spu.sourcepackage = sourcepackage
     spu.version = version
@@ -52,7 +52,7 @@
     return spu
 
 
-def create_merge_proposal(project='my-project', sourcepackage='my-package',
+def create_merge_proposal(sourcepackage, project='my-project',
                           lp_url='~foobar/my-project/my-branch/+merge/123456',
                           target_branch='lp:~foobar/my-project/trunk',
                           approved_revno=100, version='1.1'):
@@ -350,3 +350,108 @@
         '''make sure we don't allow invalid json'''
         with self.assertRaises(ValidationError):
             Workflow.objects.create(name='foo', steps='this is not json')
+
+
+class TestTicketConflicts(TestCase):
+
+    def setUp(self):
+        """Mock container creation and queue dispatching.
+
+        Also setup a common ticket conflict eco-system.
+        """
+        _m = mock.patch('ticket.models.Ticket.create_container')
+        _m.start()
+        self.addCleanup(_m.stop)
+        _m = mock.patch('ci_utils.amqp_utils.send')
+        _m.start()
+        self.addCleanup(_m.stop)
+
+        self.ticket_one = create_ticket(title='One')
+        self.ticket_two = create_ticket(title='Two')
+        sp_one = create_sourcepackage('ding')
+        sp_two = create_sourcepackage('dong')
+        self.spu_one = create_sourcepackageupload(sp_one)
+        self.spu_two = create_sourcepackageupload(sp_two)
+        self.mp_one = create_merge_proposal(sp_one)
+        self.mp_two = create_merge_proposal(sp_two)
+
+    def test_no_conflicts(self):
+        # Conflicts are only detected for `SourcePackageUpload`s with
+        # the same 'name' and 'version'.
+        subticket_one = create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_one)
+        subticket_two = create_subticket(
+            ticket=self.ticket_two, source_package_upload=self.spu_two)
+
+        self.assertEqual(
+            [], list(subticket_one.conflicts))
+        self.assertEqual(
+            [], list(subticket_two.conflicts))
+
+    def test_has_single_conflict(self):
+        # Conflicts are symmetrical across 'SubTicket's on active `Ticket`s
+        # (A conflicts with B, thus B conflicts with A) and cover
+        # `SourcePackageUpload` and `MergeProposal`s.
+        subticket_one = create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_one)
+        subticket_two = create_subticket(
+            ticket=self.ticket_two, merge_proposal=self.mp_one)
+
+        self.assertEqual(
+            [self.ticket_two], list(subticket_one.conflicts))
+        self.assertEqual(
+            [self.ticket_one], list(subticket_two.conflicts))
+
+    def test_no_conflicts_for_inactive(self):
+        # Inactive `Ticket`s (NEW, FAILED or COMPLETED) are not considered
+        # conflict targets, but still pointing to active conflicts.
+        subticket_one = create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_one)
+        subticket_two = create_subticket(
+            ticket=self.ticket_two, source_package_upload=self.spu_one)
+
+        self.ticket_two.current_workflow_step = TicketWorkflowStep.COMPLETED
+        self.ticket_two.save()
+
+        self.assertEqual([], list(subticket_one.conflicts))
+        self.assertEqual([self.ticket_one], list(subticket_two.conflicts))
+
+    def test_no_conflicts_for_failures(self):
+        # `Ticket`s that failed in any workflow steps are not considered
+        # conflict targets.
+        subticket_one = create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_one)
+        subticket_two = create_subticket(
+            ticket=self.ticket_two, source_package_upload=self.spu_one)
+
+        self.ticket_two.current_workflow_step = (
+            TicketWorkflowStep.PKG_BUILDING)
+        self.ticket_two.status = TicketWorkflowStepStatus.FAILED
+        self.ticket_two.save()
+
+        self.assertEqual([], list(subticket_one.conflicts))
+        self.assertEqual([self.ticket_one], list(subticket_two.conflicts))
+
+    def test_has_multiple_conflicts(self):
+        # Multiple conflicting tickets are distinct and ordered by id.
+        subticket_one = create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_one)
+        subticket_two = create_subticket(
+            ticket=self.ticket_two, source_package_upload=self.spu_one)
+        # Create a third conflicting ticket on a MP
+        ticket_three = create_ticket(title='Three')
+        subticket_three = create_subticket(
+            ticket=ticket_three, merge_proposal=self.mp_one)
+        # Force a multi-path join to provoke duplicated results.
+        create_subticket(
+            ticket=self.ticket_one, source_package_upload=self.spu_two)
+        create_subticket(
+            ticket=self.ticket_two, merge_proposal=self.mp_two)
+
+        self.assertEqual(
+            [self.ticket_two, ticket_three], list(subticket_one.conflicts))
+        self.assertEqual(
+            [self.ticket_one, ticket_three], list(subticket_two.conflicts))
+        self.assertEqual(
+            [self.ticket_one, self.ticket_two],
+            list(subticket_three.conflicts))

=== modified file 'ticket_system/ticket/tests/test_read_api.py'
--- ticket_system/ticket/tests/test_read_api.py	2014-09-10 11:41:44 +0000
+++ ticket_system/ticket/tests/test_read_api.py	2014-09-24 17:47:41 +0000
@@ -153,6 +153,7 @@
                         settings.TEST_DATETIME_FORMAT)),
                     u'uuid': self.ticket.uuid},
                 u'id': self.subticket.pk,
+                u'conflicts': [],
                 u'resource_uri': u'/api/v1/subticket/{0}/'.format(
                     self.subticket.pk)},
             u'type': unicode(self.artifact_1.type),
@@ -245,8 +246,35 @@
                 u'updated': unicode(self.ticket.updated.strftime(
                     settings.TEST_DATETIME_FORMAT)),
                 u'uuid': self.ticket.uuid},
+            u'conflicts': [],
         })
 
+    def test_subticket_api_conflicts(self):
+        # Each `Subticket`s points, individually, to conflicting `Tickets`
+        # This way users have a clear indication of which part (subticket)
+        # of their task might result in problem when landing.
+        another_ticket = mommy.make(
+            'Ticket', current_workflow_step=TicketWorkflowStep.QUEUED)
+        another_spu = mommy.make(
+            'SourcePackageUpload', sourcepackage=self.sourcepackage,
+            version=self.spu.version)
+        mommy.make(
+            'SubTicket', ticket=another_ticket,
+            source_package_upload=another_spu)
+
+        [old, new] = self.getResource('subticket/')['objects']
+
+        # The 'old' ticket now conflicts with 'new' (just created).
+        # Remember, 'conflicts' contains the `Ticket` resource URI.
+        self.assertEqual(
+            [new['ticket']['resource_uri']], old['conflicts'])
+
+        # The 'new' ticket does not conflict with the 'old' because it's
+        # still 'NEW' (not active). See 'test_models' for more descriptive
+        # test on this aspect.
+        self.assertEqual(
+            [], new['conflicts'])
+
     def test_get_ticket_api(self):
         obj = self.getResource('ticket/')
         self.assertEqual(obj['objects'][0], {

=== modified file 'webui/tickets/static/tickets/webui.js'
--- webui/tickets/static/tickets/webui.js	2014-08-29 18:54:41 +0000
+++ webui/tickets/static/tickets/webui.js	2014-09-24 17:47:41 +0000
@@ -185,7 +185,14 @@
         make_subticket: function (data) {
             var div = Y.Node.create("<div class='subticket'></div>"),
                 table = div.appendChild(Y.Node.create("<table>")),
-                hidden_fields = Y.Array(['id', 'resource_uri', 'current_workflow_step', 'status', 'source_package_upload']),
+                hidden_fields = Y.Array([
+                    'id',
+                    'resource_uri',
+                    'current_workflow_step',
+                    'status',
+                    'source_package_upload',
+                    'conflicts',
+                ]),
                 key,
                 value,
                 tmp_th,