From b4f1648edc2438cbd8d9a2fabaa2e37b7f3e4f8a Mon Sep 17 00:00:00 2001
From: Douglas Paz <eu@douglaspaz.com>
Date: Mon, 9 Jul 2018 12:06:38 -0300
Subject: [PATCH] Add ping endpoint, closes #155

---
 bothub/health/__init__.py |  0
 bothub/health/apps.py     |  5 +++++
 bothub/health/checks.py   | 23 +++++++++++++++++++++++
 bothub/health/tests.py    |  1 +
 bothub/health/views.py    | 34 ++++++++++++++++++++++++++++++++++
 bothub/urls.py            |  2 ++
 6 files changed, 65 insertions(+)
 create mode 100644 bothub/health/__init__.py
 create mode 100644 bothub/health/apps.py
 create mode 100644 bothub/health/checks.py
 create mode 100644 bothub/health/tests.py
 create mode 100644 bothub/health/views.py

diff --git a/bothub/health/__init__.py b/bothub/health/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/bothub/health/apps.py b/bothub/health/apps.py
new file mode 100644
index 00000000..ea5593f6
--- /dev/null
+++ b/bothub/health/apps.py
@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class HealthConfig(AppConfig):
+    name = 'health'
diff --git a/bothub/health/checks.py b/bothub/health/checks.py
new file mode 100644
index 00000000..e3ba2c59
--- /dev/null
+++ b/bothub/health/checks.py
@@ -0,0 +1,23 @@
+def check_database_connection(**kwargs):
+    from django.db import connections
+    from django.db.utils import OperationalError
+    db_conn = connections['default']
+    if not db_conn:
+        return False
+    try:
+        db_conn.cursor()
+        return True
+    except OperationalError as e:
+        return False
+
+
+def check_accessible_api(request, **kwargs):
+    import requests
+    HTTP_HOST = request.META.get('HTTP_HOST')
+    repositories_url = 'http://{}/api/repositories/'.format(HTTP_HOST)
+    request = requests.get(repositories_url)
+    try:
+        request.raise_for_status()
+        return True
+    except requests.HTTPError as e:
+        return False
diff --git a/bothub/health/tests.py b/bothub/health/tests.py
new file mode 100644
index 00000000..e4defabc
--- /dev/null
+++ b/bothub/health/tests.py
@@ -0,0 +1 @@
+# from django.test import TestCase
diff --git a/bothub/health/views.py b/bothub/health/views.py
new file mode 100644
index 00000000..3025944a
--- /dev/null
+++ b/bothub/health/views.py
@@ -0,0 +1,34 @@
+from collections import OrderedDict
+from functools import reduce
+
+from django.http import HttpResponse
+from rest_framework import status
+
+from .checks import check_database_connection
+from .checks import check_accessible_api
+
+CHECKS = [
+    check_database_connection,
+    check_accessible_api,
+]
+
+
+def ping(request):
+    checks_status = OrderedDict(map(
+        lambda check: (check.__name__, check(request=request)),
+        CHECKS))
+    healthy = reduce(
+        lambda current, status: current and status,
+        checks_status.values(),
+        True)
+    content = '{}\n{}'.format(
+        'OK' if healthy else 'something wrong happened',
+        '\n'.join(map(
+            lambda x: '{}: {}'.format(*x),
+            checks_status.items())))
+    status_code = status.HTTP_200_OK \
+        if healthy else status.HTTP_503_SERVICE_UNAVAILABLE
+    return HttpResponse(
+        content=content,
+        content_type='text/plain',
+        status=status_code)
diff --git a/bothub/urls.py b/bothub/urls.py
index bdfd5497..628f309a 100644
--- a/bothub/urls.py
+++ b/bothub/urls.py
@@ -4,12 +4,14 @@
 from rest_framework.documentation import include_docs_urls
 
 from bothub.api.routers import router as bothub_api_routers
+from bothub.health.views import ping
 
 
 urlpatterns = [
     path('api/', include(bothub_api_routers.urls)),
     path('docs/', include_docs_urls(title='API Documentation')),
     path('admin/', admin.site.urls),
+    path('ping/', ping, name='ping'),
 ]
 
 if settings.DEBUG: