BUG/MINOR: mworker: do 'program' postparser checks in read_cfg_in_discovery_mode

cfg_program_postparser() contains 2 parts:

	- check the combination of MODE_MWORKER and "program" section. if
	"program" section was parsed, MODE_MWORKER is mandatory;

	- check "command" keyword, which is mandatory for this section as
	well.

This is more appropriate now, after the master-worker refactoring, do the
first part in read_cfg_in_discovery_mode, where we already check the
combination of MODE_MWORKER and -S option.

We need to do the second part just below, in read_cfg_in_discovery_mode() as
well, because it's only the master process, who parses now program section and
programs are forked before running postparser functions in step_init_2.
Otherwise, mworker_ext_launch_all() will emit a log message, that program is
started, but actually nothing has been launched, if 'command' keyword is
absent.

This not needs to be backported, as related to the master-worker refactoring.

Author: einval22

src/haproxy.c

@@ -3102,6 +3102,7 @@ static void run_master_in_recovery_mode(int argc, char **argv)
 static void read_cfg_in_discovery_mode(int argc, char **argv)
 {
 	struct cfgfile *cfg, *cfg_tmp;
+	struct mworker_proc *proc;
 
 	/* load configs in memory and parse only global section (MODE_DISCOVERY) */
 	global.mode |= MODE_DISCOVERY;
@@ -3151,6 +3152,36 @@ static void read_cfg_in_discovery_mode(int argc, char **argv)
 		exit(EXIT_FAILURE);
 	}
 
+	/* "progam" sections, if there are any, were alredy parsed only by master
+	 * and programs are forked before calling postparser functions from
+	 * postparser list. So, all checks related to "program" section integrity
+	 * and sections vs MODE_MWORKER combinations should be done here.
+	 */
+	list_for_each_entry(proc, &proc_list, list) {
+		if (proc->options & PROC_O_TYPE_PROG) {
+			if (!(global.mode & MODE_MWORKER)) {
+				ha_alert("'program' section is defined in configuration, "
+				         "but master-worker mode (-W) is not enabled.\n");
+				exit(EXIT_FAILURE);
+			}
+
+			if ((proc->reloads == 0) && (proc->command == NULL)) {
+				if (getenv("HAPROXY_MWORKER_REEXEC") != NULL) {
+					ha_warning("Master failed to parse new configuration: "
+					           "the program section '%s' lacks a command to launch. "
+					           "It can't start a new worker and launch defined programs. "
+					           "Already running worker and programs "
+					           "will be kept. Please, check program section settings\n", proc->id);
+
+					run_master_in_recovery_mode(argc, argv);
+				} else {
+					ha_alert("The program section '%s' lacks a command to launch.\n", proc->id);
+					exit(EXIT_FAILURE);
+				}
+			}
+		}
+	}
+
 	/* in MODE_CHECK and in MODE_DUMP_CFG we just need to parse the
 	 * configuration and exit, see step_init_2()
 	 */

src/mworker-prog.c

@@ -332,31 +332,4 @@ int cfg_parse_program(const char *file, int linenum, char **args, int kwm)
 
 }
 
-int cfg_program_postparser()
-{
-	int err_code = 0;
-	struct mworker_proc *child;
-
-	if (!(global.mode & MODE_DISCOVERY))
-		return err_code;
-
-	list_for_each_entry(child, &proc_list, list) {
-		if (child->reloads == 0 && (child->options & PROC_O_TYPE_PROG)) {
-			if (child->command == NULL) {
-				ha_alert("The program section '%s' lacks a command to launch.\n", child->id);
-				err_code |= ERR_ALERT | ERR_FATAL;
-			}
-		}
-	}
-
-	if (use_program && !(global.mode & MODE_MWORKER)) {
-		ha_alert("Can't use a 'program' section without master worker mode.\n");
-		err_code |= ERR_ALERT | ERR_FATAL;
-	}
-
-	return err_code;
-}
-
-
 REGISTER_CONFIG_SECTION("program", cfg_parse_program, NULL);
-REGISTER_CONFIG_POSTPARSER("program", cfg_program_postparser);