Merge pull request #230 from release-engineering/health-check

Add a simple health check API endpoint

estuary/api/health_check.py

@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-3.0+
+
+from __future__ import unicode_literals
+
+from neomodel import db
+
+from estuary import log
+
+
+def health_check():
+    """Determine the health of the API by checking if the database interactions are working."""
+    msg = 'Health check OK'
+    status = 200
+    try:
+        # Just perform a simple math operation that doesn't rely on any data being present in the
+        # database
+        results, _ = db.cypher_query('RETURN sqrt(4)')
+        assert results[0][0] == 2.0
+    except:  # noqa E722
+        log.exception('An exception was encountered when verifying the database connection in the '
+                      'health check API endpoint')
+        msg = 'The health check failed while verifying the database connection'
+        status = 503
+
+    return (msg, status, [('Content-Type', 'text/plain')])

estuary/app.py

@@ -14,6 +14,7 @@
 from estuary.logger import init_logging
 from estuary.error import json_error, ValidationError
 from estuary.api.v1 import api_v1
+from estuary.api.health_check import health_check
 
 
 def load_config(app):
@@ -115,6 +116,7 @@ def create_app(config_obj=None):
     app.register_error_handler(ServiceUnavailable, json_error)
     app.register_error_handler(AuthError, json_error)
     app.register_blueprint(api_v1, url_prefix='/api/v1')
+    app.add_url_rule('/healthcheck', view_func=health_check)
     try:
         from estuary.api.monitoring import monitoring_api, configure_monitoring
         app.register_blueprint(monitoring_api, url_prefix='/monitoring')

tests/api/test_health_check.py

@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-3.0+
+
+from __future__ import unicode_literals
+
+from mock import patch
+
+
+def test_healthcheck(client):
+    """Test the health check endpoint is working."""
+    rv = client.get('/healthcheck')
+    assert rv.status_code == 200
+    assert rv.data.decode('utf-8') == 'Health check OK'
+
+
+def test_healthcheck_failure(client):
+    """Test the health check endpoint shows failures."""
+    with patch('estuary.api.health_check.db') as mock_db:
+        mock_db.cypher_query.side_effect = RuntimeError('Some failure')
+        rv = client.get('/healthcheck')
+    assert rv.status_code == 503
+    assert rv.data.decode('utf-8') == \
+        'The health check failed while verifying the database connection'