flush-memcached: Respect MEMCACHED_LOCATION; handle errors.

Fixes #13238.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

scripts/setup/flush-memcached

@@ -1,6 +1,25 @@
-#!/usr/bin/env bash
-set -e
+#!/usr/bin/env python3
 
-# Flush memcached
-echo "Flushing memcached..."
-echo 'flush_all' | nc -w 1 localhost 11211
+import os
+import socket
+import sys
+from urllib.parse import urlsplit
+
+BASE_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "../..")
+sys.path.append(BASE_DIR)
+
+import scripts.lib.setup_path_on_import
+from zproject import settings
+
+url = urlsplit("//" + settings.MEMCACHED_LOCATION)
+
+print("Flushing memcached...")
+with socket.create_connection((url.hostname, url.port)) as f:
+    f.sendall(b"flush_all\r\n")
+    response = b""
+    while b"\n" not in response:
+        response += f.recv(4096)
+    if response != b"OK\r\n":
+        print(response, file=sys.stderr)
+        print("Failed to flush memcached", file=sys.stderr)
+        sys.exit(1)