feat(api): Allow using an unreleased image for the run command.

This is useful for build steps which must be completed before an app is fully
deployed to deis, for example asset compilation.

rootfs/api/models/app.py

@@ -684,7 +684,7 @@ def logs(self, log_lines=str(settings.LOG_LINES)):
         # cast content to string since it comes as bytes via the requests object
         return str(r.content.decode('utf-8'))
 
-    def run(self, user, command):
+    def run(self, user, command, image=None):
         def pod_name(size=5, chars=string.ascii_lowercase + string.digits):
             return ''.join(random.choice(chars) for _ in range(size))
 
@@ -695,7 +695,8 @@ def pod_name(size=5, chars=string.ascii_lowercase + string.digits):
 
         app_settings = self.appsettings_set.latest()
         # use slugrunner image for app if buildpack app otherwise use normal image
-        image = settings.SLUGRUNNER_IMAGE if release.build.type == 'buildpack' else release.image
+        if image is None:
+            image = settings.SLUGRUNNER_IMAGE if release.build.type == 'buildpack' else release.image
 
         data = self._gather_app_settings(release, app_settings, process_type='run', replicas=1)
 

rootfs/api/views.py

@@ -238,7 +238,7 @@ def run(self, request, **kwargs):
         app = self.get_object()
         if not request.data.get('command'):
             raise DeisException("command is a required field")
-        rc, output = app.run(self.request.user, request.data['command'])
+        rc, output = app.run(self.request.user, request.data['command'], image=request.data.get('image'))
         return Response({'exit_code': rc, 'output': str(output)})
 
     def update(self, request, **kwargs):