Implement retrieval "Farm" APIs

We intend to improve the UI/UX when adding a new Project by enhancing the registration process for Farms on the "Register Project" page.
To prepare for this improvement, we have added two API endpoints to retrieve Farm's data.

promgen/filters.py

@@ -19,3 +19,8 @@ class RuleFilter(django_filters.rest_framework.FilterSet):
     name = django_filters.CharFilter(field_name="name", lookup_expr="contains")
     parent = django_filters.CharFilter(field_name="parent__name", lookup_expr="contains")
     enabled = django_filters.BooleanFilter(field_name="enabled")
+
+
+class FarmFilter(django_filters.rest_framework.FilterSet):
+    name = django_filters.CharFilter(field_name="name", lookup_expr="contains")
+    source = django_filters.CharFilter(field_name="source", lookup_expr="exact")

promgen/rest.py

@@ -1,6 +1,7 @@
 # Copyright (c) 2019 LINE Corporation
 # These sources are released under the terms of the MIT license: see LICENSE
 
+from django.core.serializers import get_serializer
 from django.http import HttpResponse
 from django.views.generic import View
 from rest_framework import permissions, viewsets
@@ -110,3 +111,23 @@ def targets(self, request, name):
             prometheus.render_config(project=self.get_object()),
             content_type="application/json",
         )
+
+
+class FarmViewSet(viewsets.ModelViewSet):
+    queryset = models.Farm.objects.all()
+    filterset_class = filters.FarmFilter
+    serializer_class = serializers.FarmSerializer
+    lookup_value_regex = "[^/]+"
+    lookup_field = "id"
+
+    def retrieve(self, request, id):
+        farm = self.get_object()
+        farm_data = self.get_serializer(farm).data
+
+        hosts = farm.host_set.all()
+        hosts_data = serializers.HostSerializer(hosts, many=True).data
+        farm_detail = {
+            **farm_data,
+            "hosts": hosts_data
+        }
+        return Response(farm_detail)

promgen/serializers.py

@@ -102,3 +102,19 @@ def to_representation(self, obj):
             "labels": obj.labels,
             "annotations": annotations,
         }
+
+
+class FarmSerializer(serializers.ModelSerializer):
+    url = WebLinkField()
+
+    class Meta:
+        model = models.Farm
+        fields = '__all__'
+
+
+class HostSerializer(serializers.ModelSerializer):
+    url = WebLinkField()
+
+    class Meta:
+        model = models.Host
+        exclude = ("id", "farm")

promgen/tests/examples/rest.farm.1.json

@@ -0,0 +1,12 @@
+{
+  "id": 1,
+  "url": "http://promgen.example.com/farm/1",
+  "name": "test-farm",
+  "source": "promgen",
+  "hosts": [
+    {
+      "name": "host.example.com",
+      "url": "http://promgen.example.com/host/host.example.com"
+    }
+  ]
+}

promgen/tests/examples/rest.farm.json

@@ -0,0 +1,7 @@
+[
+  {
+    "id": 1,
+    "url": "http://promgen.example.com/farm/1",
+    "name": "test-farm","source":"promgen"
+  }
+]

promgen/tests/test_rest.py

@@ -3,6 +3,7 @@
 
 
 from django.test import override_settings
+from django.urls import reverse
 
 from promgen import models, rest, tests
 
@@ -21,3 +22,41 @@ def test_alert(self):
         response = self.fireAlert()
         self.assertEqual(response.status_code, 202)
         self.assertCount(models.Alert, 1, "Alert Queued")
+
+    @override_settings(PROMGEN=tests.SETTINGS)
+    def test_retrieve_farm(self):
+        expected = tests.Data("examples", "rest.farm.json").json()
+
+        # Check retrieving all farms
+        response = self.client.get(reverse("api:farm-list"))
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), expected)
+
+        # Check retrieving all farms whose "name" contains "farm"
+        response = self.client.get(reverse("api:farm-list"), {"name": "farm"})
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), expected)
+
+        # Check retrieving all farms whose "source" is "promgen"
+        response = self.client.get(reverse("api:farm-list"), {"source": "promgen"})
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json(), expected)
+
+        # Check retrieving farms with a non-existent "name" returns an empty list
+        response = self.client.get(reverse("api:farm-list"), {"name": "other-name"})
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(response.data), 0)
+
+        # Check retrieving farms with a non-existent "source" returns an empty list
+        response = self.client.get(reverse("api:farm-list"), {"source": "other-source"})
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(response.data), 0)
+
+
+        farm = models.Farm.objects.get(id=1)
+        models.Host.objects.create(name="host.example.com", farm=farm)
+        expected = tests.Data("examples", "rest.farm.1.json").json()
+
+        # Check retrieving the farm whose "id" is "1", including the list of hosts.
+        response = self.client.get(reverse("api:farm-detail", args=[1]))
+        self.assertEqual(response.json(), expected)

promgen/urls.py

@@ -28,6 +28,7 @@
 router.register("service", rest.ServiceViewSet)
 router.register("shard", rest.ShardViewSet)
 router.register("project", rest.ProjectViewSet)
+router.register("farm", rest.FarmViewSet)
 
 
 urlpatterns = [