plugin: Handle log notifications from plugins

Logs are parsed and injected into the main daemon's logs.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

contrib/plugins/helloworld.py

@@ -45,12 +45,27 @@ def json_getmanifest(request):
     }
 
 
+def plugin_log(message, level="info"):
+    payload = {
+        "jsonrpc": "2.0",
+        "method": "log",
+        "params": {
+            "level": level,
+            "message": message,
+        }
+    }
+    json.dump(payload, fp=sys.stdout)
+    sys.stdout.write('\n\n')
+    sys.stdout.flush()
+
+
 def json_init(request, options, configuration):
     """The main daemon is telling us the relevant cli options
     """
     global greeting
-
     greeting = request['params']['options']['greeting']
+    plugin_log("Plugin helloworld.py initialized with greeting \"{}\"".format(greeting), "debug")
+
     return "ok"
 
 

lightningd/plugin.c

@@ -234,6 +234,40 @@ static void plugin_request_queue(struct plugin *plugin,
 	io_wake(plugin);
 }
 
+static void plugin_log_handle(struct plugin *plugin, const jsmntok_t *paramstok)
+{
+	const jsmntok_t *msgtok, *leveltok;
+	enum log_level level;
+	msgtok = json_get_member(plugin->buffer, paramstok, "message");
+	leveltok = json_get_member(plugin->buffer, paramstok, "level");
+
+	if (!msgtok || msgtok->type != JSMN_STRING) {
+		plugin_kill(plugin, "Log notification from plugin doesn't have "
+				    "a string \"message\" field");
+		return;
+	}
+
+	if (!leveltok || json_tok_streq(plugin->buffer, leveltok, "info"))
+		level = LOG_INFORM;
+	else if (json_tok_streq(plugin->buffer, leveltok, "debug"))
+		level = LOG_DBG;
+	else if (json_tok_streq(plugin->buffer, leveltok, "warn"))
+		level = LOG_UNUSUAL;
+	else if (json_tok_streq(plugin->buffer, leveltok, "error"))
+		level = LOG_BROKEN;
+	else {
+		plugin_kill(plugin,
+			    "Unknown log-level %.*s, valid values are "
+			    "\"debug\", \"info\", \"warn\", or \"error\".",
+			    json_tok_len(leveltok),
+			    json_tok_contents(plugin->buffer, leveltok));
+		return;
+	}
+
+	log_(plugin->log, level, "%.*s", msgtok->end - msgtok->start,
+	     plugin->buffer + msgtok->start);
+}
+
 static void plugin_notification_handle(struct plugin *plugin,
 				       const jsmntok_t *toks)
 {

tests/test_plugin.py

@@ -47,6 +47,10 @@ def test_rpc_passthrough(node_factory):
     cmd = [hlp for hlp in n.rpc.help()['help'] if 'hello' in hlp['command']]
     assert(len(cmd) == 1)
 
+    # While we're at it, let's check that helloworld.py is logging
+    # correctly via the notifications plugin->lightningd
+    assert n.daemon.is_in_log('Plugin helloworld.py initialized')
+
     # Now try to call it and see what it returns:
     greet = n.rpc.hello(name='Sun')
     assert(greet == "Hello Sun")