add instance install bundle endpoint

add scaffolding for instance install_bundle endpoint

- add instance_install_bundle view (does not do anything yet)
- add `instance_install_bundle` related field to serializer
- add `/install_bundle` to instance URL
- `/install_bundle` only available for execution and hop node
- `/install_bundle` endpoint response contain a downloadable tgz with moc data

TODO: add actual data to the install bundle response

Signed-off-by: Hao Liu <haoli@redhat.com>

awx/api/views/__init__.py

@@ -174,6 +174,7 @@ from awx.api.views.webhooks import WebhookKeyView, GithubWebhookReceiver, Gitlab
 from awx.api.pagination import UnifiedJobEventPagination
 from awx.main.utils import set_environ
 
+from awx.api.views.instance_install_bundle import InstanceInstallBundle  # noqa
 
 logger = logging.getLogger('awx.api.views')
 

awx/api/views/instance_install_bundle.py

@@ -0,0 +1,54 @@
+# Copyright (c) 2018 Red Hat, Inc.
+# All Rights Reserved.
+
+import os
+import tarfile
+import tempfile
+
+from awx.api import serializers
+from awx.api.generics import GenericAPIView, Response
+from awx.api.permissions import IsSystemAdminOrAuditor
+from awx.main import models
+from django.utils.translation import gettext_lazy as _
+from rest_framework import status
+from django.http import HttpResponse
+
+# generate install bundle for the instance
+class InstanceInstallBundle(GenericAPIView):
+
+    name = _('Install Bundle')
+    model = models.Instance
+    serializer_class = serializers.InstanceSerializer
+    permission_classes = (IsSystemAdminOrAuditor,)
+
+    def get(self, request, *args, **kwargs):
+        instance_obj = self.get_object()
+
+        # if the instance is not a hop or execution node than return 400
+        if instance_obj.node_type not in ('execution', 'hop'):
+            return Response(
+                data=dict(msg=_('Install bundle can only be generated for execution or hop nodes.')),
+                status=status.HTTP_400_BAD_REQUEST,
+            )
+
+        # TODO: add actual data into the bundle
+        # create a named temporary file directory to store the content of the install bundle
+        with tempfile.TemporaryDirectory() as tmpdirname:
+            # create a empty file named "moc_content.txt" in the temporary directory
+            with open(os.path.join(tmpdirname, 'mock_content.txt'), 'w') as f:
+                f.write('mock content')
+
+            # create empty directory in temporary directory
+            os.mkdir(os.path.join(tmpdirname, 'mock_dir'))
+
+            # tar.gz and create a temporary file from the temporary directory
+            # the directory will be renamed and prefixed with the hostname of the instance
+            with tempfile.NamedTemporaryFile(suffix='.tar.gz') as tmpfile:
+                with tarfile.open(tmpfile.name, 'w:gz') as tar:
+                    tar.add(tmpdirname, arcname=f"{instance_obj.hostname}_install_bundle")
+
+                # read the temporary file and send it to the client
+                with open(tmpfile.name, 'rb') as f:
+                    response = HttpResponse(f.read(), status=status.HTTP_200_OK)
+                    response['Content-Disposition'] = f"attachment; filename={instance_obj.hostname}_install_bundle.tar.gz"
+                    return response