fixed #112

core/config.c

@@ -465,3 +465,16 @@ add:
 
 }
 
+void uwsgi_fallback_config() {
+	if (uwsgi.fallback_config && uwsgi.last_exit_code == 1) {
+		uwsgi_log_verbose("!!! %s (pid: %d) exited with status %d !!!\n", uwsgi.binary_path, (int) getpid(), uwsgi.last_exit_code);
+		uwsgi_log_verbose("!!! Fallback config to %s !!!\n", uwsgi.fallback_config);
+		char *argv[3];
+		argv[0] = uwsgi.binary_path;
+		argv[1] = uwsgi.fallback_config;
+		argv[2] = NULL;
+        	execvp(uwsgi.binary_path, argv);
+        	uwsgi_error("execvp()");
+        	// never here
+	}
+}

core/utils.c

@@ -3736,3 +3736,9 @@ void uwsgi_envdirs(struct uwsgi_string_list *envdirs) {
 void uwsgi_opt_envdir(char *opt, char *value, void *foobar) {
 	uwsgi_envdir(value);
 }
+
+void uwsgi_exit(int status) {
+	uwsgi.last_exit_code = status;
+	// disable macro expansion
+	(exit)(status);
+}

core/uwsgi.c

@@ -72,6 +72,7 @@ static struct uwsgi_option uwsgi_base_options[] = {
 	{"xml", required_argument, 'x', "load config from xml file", uwsgi_opt_load_xml, NULL, UWSGI_OPT_IMMEDIATE},
 #endif
 	{"config", required_argument, 0, "load configuration using the pluggable system", uwsgi_opt_load_config, NULL, UWSGI_OPT_IMMEDIATE},
+	{"fallback-config", required_argument, 0, "re-exec uwsgi with the specified config when exit code is 1", uwsgi_opt_set_str, &uwsgi.fallback_config, UWSGI_OPT_IMMEDIATE},
 	{"strict", no_argument, 0, "enable strict mode (placeholder cannot be used)", uwsgi_opt_true, &uwsgi.strict, UWSGI_OPT_IMMEDIATE},
 
 	{"skip-zero", no_argument, 0, "skip check of file descriptor 0", uwsgi_opt_true, &uwsgi.skip_zero, 0},
@@ -1762,6 +1763,8 @@ int main(int argc, char *argv[], char *envp[]) {
 	uwsgi_register_clock(&uwsgi_unix_clock);
 	uwsgi_set_clock("unix");
 
+	// fallback config
+	atexit(uwsgi_fallback_config);
 	// manage/flush logs
 	atexit(uwsgi_flush_logs);
 	// clear sockets, pidfiles...

uwsgi.h

@@ -1561,12 +1561,17 @@ void uwsgi_opt_load_config(char *, char *, void *);
 #define uwsgi_instance_is_dying (uwsgi.status.gracefully_destroying || uwsgi.status.brutally_destroying)
 #define uwsgi_instance_is_reloading (uwsgi.status.gracefully_reloading || uwsgi.status.brutally_reloading)
 
+#define exit(x) uwsgi_exit(x)
+
 struct uwsgi_server {
 
 	// store the machine hostname
 	char hostname[256];
 	int hostname_len;
 
+	// used to store the exit code for atexit hooks
+	int last_exit_code;
+
 	int (*proto_hooks[UWSGI_PROTO_MAX_CHECK]) (struct wsgi_request *, char *, char *, uint16_t);
 	struct uwsgi_configurator *configurators;
 
@@ -2162,7 +2167,7 @@ struct uwsgi_server {
 	mode_t chmod_logfile_value;
 	int listen_queue;
 
-	char *file_config;
+	char *fallback_config;
 
 #ifdef UWSGI_ROUTING
 	struct uwsgi_router *routers;
@@ -4124,6 +4129,9 @@ int uwsgi_register_fsmon(struct uwsgi_string_list *);
 int uwsgi_fsmon_event(int);
 void uwsgi_fsmon_setup();
 
+void uwsgi_exit(int) __attribute__ ((__noreturn__));
+void uwsgi_fallback_config();
+
 #ifdef __cplusplus
 }
 #endif