From e13ef93836f77e5bcf1e23b8a46dae77cda2773f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lauri=20V=C3=B5sandi?= <lauri@k-space.ee>
Date: Sat, 24 Sep 2022 08:43:25 +0300
Subject: [PATCH] Add replica support

---
 bind-sidecar.py | 46 +++++++++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/bind-sidecar.py b/bind-sidecar.py
index f23204b..6c95b10 100755
--- a/bind-sidecar.py
+++ b/bind-sidecar.py
@@ -1,13 +1,19 @@
 #!/usr/bin/env python3
+import argparse
 import asyncio
 import ecs_logging
 import logging
 import os
-import sys
+import signal
+import socket
 from kubernetes_asyncio.client.api_client import ApiClient
 from kubernetes_asyncio import client, config, watch
 from time import time
 
+parser = argparse.ArgumentParser()
+parser.add_argument("--replica", action="store_true")
+args = parser.parse_args()
+
 # Get the Logger
 logger = logging.getLogger()
 logger.setLevel(logging.INFO)
@@ -17,14 +23,6 @@ handler = logging.StreamHandler()
 handler.setFormatter(ecs_logging.StdlibFormatter())
 logger.addHandler(handler)
 
-ZONEFILE_TEMPLATE = """
-@ IN SOA ns1.%(zone)s. hostmaster.%(zone)s. (2022060820 300 300 300 300)
-    NS ns1.%(zone)s.
-ns1 A  %(ip)s
-"""
-
-_, ip = sys.argv
-
 PATH_CONFIG = "/var/bind/bind.conf"
 PATH_ZONEFILE = "/var/bind/db.%s"
 
@@ -32,11 +30,21 @@ active_zones = set()
 
 
 def update_config():
+    master = socket.gethostbyname("bind-primary")
     with open(PATH_CONFIG + ".part", "w") as fh:
         for zone in active_zones:
             path = PATH_ZONEFILE % zone
-            fh.write("zone \"%s\" { type master; file \"%s\"; };\n" % (zone, path))
+            if args.replica:
+                fh.write("zone \"%s\" { type slave; masters { %s key zone-transfer; }; };\n" % (zone, master))
+            else:
+                fh.write("zone \"%s\" { type master; file \"%s\"; };\n" % (zone, path))
     os.rename(PATH_CONFIG + ".part", PATH_CONFIG)
+    logger.debug("File %s updated", PATH_CONFIG)
+    try:
+        with open("/var/bind/named.pid") as fh:
+            os.kill(int(fh.read()), signal.SIGHUP)
+    except FileNotFoundError:
+        logger.warn("File /var/bind/named.pid not found, assuming Bind not running yet")
 
 
 async def update_loop(v1, apps_api, api_instance, revision):
@@ -50,15 +58,15 @@ async def update_loop(v1, apps_api, api_instance, revision):
         if event["type"] == "ADDED":
             zone = event["object"]["metadata"]["name"]
             active_zones.add(zone)
-            path = PATH_ZONEFILE % zone
-            logger.info("Adding zone: %s", zone)
-            if not os.path.exists(path):
-                with open(path + ".part", "w") as fh:
-                    fh.write(ZONEFILE_TEMPLATE % {
-                        "ip": ip,
-                        "zone": zone
-                    })
-                os.rename(path + ".part", path)
+            if not args.replica:
+                path = PATH_ZONEFILE % zone
+                logger.info("Adding zone: %s", zone)
+                if not os.path.exists(path):
+                    with open(path + ".part", "w") as fh:
+                        fh.write("@ IN SOA ns1.%(zone)s. hostmaster.%(zone)s. (1 300 300 300 300)\n" % locals())
+                        fh.write("     NS  ns1.%(zone)s.\n" % locals())
+                        fh.write("ns1  A   127.0.0.1\n")
+                    os.rename(path + ".part", path)
             update_config()
         elif event["type"] == "DELETED":
             logger.info("Removing zone: %s", zone)