replace target files based on timestamp

instead of relying on the cached certificate file being updated.
This allows multiple configuration files for the same domain.
To avoid replacing existing entries, the format is changed from
a dictionary to a list, and setting domains in acme.conf is no
longer supported.

acertmgr.py

@@ -72,6 +72,15 @@ class ACMERequestHandler(SimpleHTTPRequestHandler):
 def start_standalone(server):
 	server.serve_forever()
 
+# @brief check whether existing target file is still valid or source crt has been updated
+# @param target string containing the path to the target file
+# @param crt_file string containing the path to the certificate file
+# @return True if target file is at least as new as the certificate, False otherwise
+def target_isCurrent(target, crt_file):
+	target_date = os.path.getmtime(target)
+	crt_date = os.path.getmtime(crt_file)
+	return target_date >= crt_date
+
 # @brief check whether existing certificate is still valid or expiring soon
 # @param crt_file string containing the path to the certificate file
 # @param ttl_days the minimum amount of days for which the certificate must be valid
@@ -230,22 +239,22 @@ if __name__ == "__main__":
 			config = yaml.load(config_fd)
 	if not config:
 		config = {}
-	if 'domains' not in config:
-		config['domains'] = {}
 	if 'defaults' not in config:
 		config['defaults'] = {}
 
+	config['domains'] = []
 	# load domain configuration
 	for config_file in os.listdir(ACME_CONFD):
 		if config_file.endswith(".conf"):
 			with open(ACME_CONFD + config_file) as config_fd:
-				config['domains'].update(yaml.load(config_fd))
+				for entry in yaml.load(config_fd).items():
+					config['domains'].append(entry)
 
 	# post-update actions (run only once)
 	actions = set()
 
 	# check certificate validity and obtain/renew certificates if needed
-	for domain, domaincfgs in config['domains'].items():
+	for domain, domaincfgs in config['domains']:
 		# skip domains without any output files
 		if domaincfgs is None:
 			continue
@@ -253,8 +262,9 @@ if __name__ == "__main__":
 		ttl_days = int(config.get('ttl_days', 15))
 		if not cert_isValid(crt_file, ttl_days):
 			cert_get(domain, config)
-			for domaincfg in domaincfgs:
-				cfg = complete_config(domaincfg, config['defaults'])
+		for domaincfg in domaincfgs:
+			cfg = complete_config(domaincfg, config['defaults'])
+			if not target_isCurrent(cfg['path'], crt_file):
 				cert_put(domain, cfg)
 
 		# run post-update actions