Reconfigure on module-added event

- Put config file generation in "expand-config" helper command. Handle
  the special case when the configuration does not exist with an
  hardcoded default.

- Invoke the helper in create-module and at every service startup.

- Restart (and reconfigure) DNSMasq if a Samba instance appears on the
  local node.

imageroot/actions/configure-module/20configure

@@ -7,29 +7,11 @@
 
 import json
 import sys
+import agent
 
 request = json.load(sys.stdin)
 
 # write dnsmasq configuration to easy json file, will be used by UI
 open("config.json", "w").write(json.dumps(request))
 
-# convert json to configuration file
-with open("dnsmasq.d/00config.conf", "w") as file:
-    file.write("# This file is automatically generated by NethServer, manual changes will be lost.\n")
-    # write interface only if dhcp-server or dns-server are enabled
-    if request["dhcp-server"]["enabled"] or request["dns-server"]["enabled"]:
-        file.write("interface=" + request["interface"] + "\n")
-
-    # write dhcp-server configuration
-    if request["dhcp-server"]["enabled"]:
-        file.write("dhcp-range=set:default," + request["dhcp-server"]["start"] + "," + request["dhcp-server"]["end"] + "," + str(request["dhcp-server"]["lease"]) + "h\n")
-
-    # write dns-server configuration
-    if request["dns-server"]["enabled"]:
-        file.write("server=" + request["dns-server"]["primary-server"] + "\n")
-        if request["dns-server"]["secondary-server"] != "":
-            file.write("server=" + request["dns-server"]["secondary-server"] + "\n")
-
-    else:
-        # shut down dns server if not enabled
-        file.write("port=0\n")
+agent.run_helper('expand-config').check_returncode()

imageroot/actions/create-module/20default_config

@@ -6,22 +6,9 @@
 #
 
 import json
+import agent
 
-config = {
-    "interface": "",
-    "dhcp-server": {
-        "enabled": False,
-        "start": "",
-        "end": "",
-        "lease": 12
-    },
-    "dns-server": {
-        "enabled": False,
-        "primary-server": "",
-        "secondary-server": ""
-    },
-}
-
-open("config.json", "w").write(json.dumps(config))
+# Force the initialization of config.json for get-configuration:
+agent.run_helper('expand-config').check_returncode()
 
 open("dns-records.json", "w").write(json.dumps({"records": []}))

imageroot/bin/expand-config

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+
+#
+# Copyright (C) 2024 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+import json
+import sys
+import agent
+
+# Read configuration from a JSON file or initialize it.
+try:
+    config = json.load(open("config.json"))
+except FileNotFoundError:
+    print(agent.SD_NOTICE, "Generating a new config.json file...", file=sys.stderr)
+    config = {
+        "interface": "",
+        "dhcp-server": {
+            "enabled": False,
+            "start": "",
+            "end": "",
+            "lease": 12
+        },
+        "dns-server": {
+            "enabled": False,
+            "primary-server": "",
+            "secondary-server": ""
+        },
+    }
+    json.dump(config, fp=open("config.json", "w"))
+
+
+# convert json to configuration file
+with open("dnsmasq.d/00config.conf", "w") as file:
+    file.write("# This file is automatically generated by NethServer, manual changes will be lost.\n")
+    # write interface only if dhcp-server or dns-server are enabled
+    if config["dhcp-server"]["enabled"] or config["dns-server"]["enabled"]:
+        file.write("interface=" + config["interface"] + "\n")
+
+    # write dhcp-server configuration
+    if config["dhcp-server"]["enabled"]:
+        file.write("dhcp-range=set:default," + config["dhcp-server"]["start"] + "," + config["dhcp-server"]["end"] + "," + str(config["dhcp-server"]["lease"]) + "h\n")
+
+    # write dns-server configuration
+    if config["dns-server"]["enabled"]:
+        file.write("server=" + config["dns-server"]["primary-server"] + "\n")
+        if config["dns-server"]["secondary-server"] != "":
+            file.write("server=" + config["dns-server"]["secondary-server"] + "\n")
+    else:
+        # shut down dns server if not enabled
+        file.write("port=0\n")

imageroot/dnsmasq.service

@@ -13,6 +13,7 @@ TimeoutStopSec=70
 ExecStartPre=/bin/rm \
         -f %t/%n.ctr-id
 ExecStartPre=runagent -m %N reload_hosts
+ExecStartPre=runagent -m %N expand-config
 ExecStart=/usr/bin/podman run \
         --cidfile=%t/%n.ctr-id \
         --cgroups=no-conmon \

imageroot/events/module-added/10restart_dnsmasq

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+#
+# Copyright (C) 2024 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+import json
+import os
+import sys
+
+import agent
+
+data = json.load(sys.stdin)
+
+# skip if the event comes from another node
+if os.environ['NODE_ID'] != str(data['node']):
+    sys.exit(0)
+
+agent.run_helper('systemctl', 'restart', os.getenv('MODULE_ID'))