Add the endpoint for the healthcheck.

counterpartylib/lib/api.py

@@ -817,6 +817,16 @@ def _set_cors_headers(response):
                 response.headers['Access-Control-Allow-Methods'] = 'GET, POST, OPTIONS'
                 response.headers['Access-Control-Allow-Headers'] = 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Authorization'
 
+        @app.route('/healthz', methods=['GET'])
+        def handle_healthz():
+            msg, code = 'Healthy', 200
+            try:
+                latestBlockIndex = backend.getblockcount()
+                check_database_state(self.db, latestBlockIndex)
+            except DatabaseError:
+                msg, code = 'Unhealthy', 503
+            return flask.Response(msg, code, mimetype='text/plain')
+
         @app.route('/', defaults={'args_path': ''}, methods=['GET', 'POST', 'OPTIONS'])
         @app.route('/<path:args_path>',  methods=['GET', 'POST', 'OPTIONS'])
         # Only require authentication if RPC_PASSWORD is set.