diff --git a/src/extcheck.c b/src/extcheck.c
new file mode 100644
index 0000000..2a577b1
--- /dev/null
+++ b/src/extcheck.c
@@ -0,0 +1,669 @@
+/*
+ * External health-checks functions.
+ *
+ * Copyright 2000-2009,2020 Willy Tarreau <w@1wt.eu>
+ * Copyright 2014 Horms Solutions Ltd, Simon Horman <horms@verge.net.au>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <haproxy/api.h>
+#include <haproxy/cfgparse.h>
+#include <haproxy/check.h>
+#include <haproxy/global.h>
+#include <haproxy/list.h>
+#include <haproxy/log.h>
+#include <haproxy/proxy.h>
+#include <haproxy/server.h>
+#include <haproxy/signal.h>
+#include <haproxy/task.h>
+#include <haproxy/thread.h>
+#include <haproxy/time.h>
+#include <haproxy/tools.h>
+
+
+static struct list pid_list = LIST_HEAD_INIT(pid_list);
+static struct pool_head *pool_head_pid_list;
+__decl_spinlock(pid_list_lock);
+
+struct extcheck_env {
+	char *name;	/* environment variable name */
+	int vmaxlen;	/* value maximum length, used to determine the required memory allocation */
+};
+
+/* environment variables memory requirement for different types of data */
+#define EXTCHK_SIZE_EVAL_INIT 0                  /* size determined during the init phase,
+                                                  * such environment variables are not updatable. */
+#define EXTCHK_SIZE_ULONG     20                 /* max string length for an unsigned long value */
+#define EXTCHK_SIZE_UINT      11                 /* max string length for an unsigned int value */
+#define EXTCHK_SIZE_ADDR      INET6_ADDRSTRLEN+1 /* max string length for an address */
+
+/* external checks environment variables */
+enum {
+	EXTCHK_PATH = 0,
+
+	/* Proxy specific environment variables */
+	EXTCHK_HAPROXY_PROXY_NAME,	/* the backend name */
+	EXTCHK_HAPROXY_PROXY_ID,	/* the backend id */
+	EXTCHK_HAPROXY_PROXY_ADDR,	/* the first bind address if available (or empty) */
+	EXTCHK_HAPROXY_PROXY_PORT,	/* the first bind port if available (or empty) */
+
+	/* Server specific environment variables */
+	EXTCHK_HAPROXY_SERVER_NAME,	/* the server name */
+	EXTCHK_HAPROXY_SERVER_ID,	/* the server id */
+	EXTCHK_HAPROXY_SERVER_ADDR,	/* the server address */
+	EXTCHK_HAPROXY_SERVER_PORT,	/* the server port if available (or empty) */
+	EXTCHK_HAPROXY_SERVER_MAXCONN,	/* the server max connections */
+	EXTCHK_HAPROXY_SERVER_CURCONN,	/* the current number of connections on the server */
+
+	EXTCHK_SIZE
+};
+
+const struct extcheck_env extcheck_envs[EXTCHK_SIZE] = {
+	[EXTCHK_PATH]                   = { "PATH",                   EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_PROXY_NAME]     = { "HAPROXY_PROXY_NAME",     EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_PROXY_ID]       = { "HAPROXY_PROXY_ID",       EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_PROXY_ADDR]     = { "HAPROXY_PROXY_ADDR",     EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_PROXY_PORT]     = { "HAPROXY_PROXY_PORT",     EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_SERVER_NAME]    = { "HAPROXY_SERVER_NAME",    EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_SERVER_ID]      = { "HAPROXY_SERVER_ID",      EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_SERVER_ADDR]    = { "HAPROXY_SERVER_ADDR",    EXTCHK_SIZE_ADDR },
+	[EXTCHK_HAPROXY_SERVER_PORT]    = { "HAPROXY_SERVER_PORT",    EXTCHK_SIZE_UINT },
+	[EXTCHK_HAPROXY_SERVER_MAXCONN] = { "HAPROXY_SERVER_MAXCONN", EXTCHK_SIZE_EVAL_INIT },
+	[EXTCHK_HAPROXY_SERVER_CURCONN] = { "HAPROXY_SERVER_CURCONN", EXTCHK_SIZE_ULONG },
+};
+
+void block_sigchld(void)
+{
+	sigset_t set;
+	sigemptyset(&set);
+	sigaddset(&set, SIGCHLD);
+	assert(ha_sigmask(SIG_BLOCK, &set, NULL) == 0);
+}
+
+void unblock_sigchld(void)
+{
+	sigset_t set;
+	sigemptyset(&set);
+	sigaddset(&set, SIGCHLD);
+	assert(ha_sigmask(SIG_UNBLOCK, &set, NULL) == 0);
+}
+
+static struct pid_list *pid_list_add(pid_t pid, struct task *t)
+{
+	struct pid_list *elem;
+	struct check *check = t->context;
+
+	elem = pool_alloc(pool_head_pid_list);
+	if (!elem)
+		return NULL;
+	elem->pid = pid;
+	elem->t = t;
+	elem->exited = 0;
+	check->curpid = elem;
+	LIST_INIT(&elem->list);
+
+	HA_SPIN_LOCK(PID_LIST_LOCK, &pid_list_lock);
+	LIST_ADD(&pid_list, &elem->list);
+	HA_SPIN_UNLOCK(PID_LIST_LOCK, &pid_list_lock);
+
+	return elem;
+}
+
+static void pid_list_del(struct pid_list *elem)
+{
+	struct check *check;
+
+	if (!elem)
+		return;
+
+	HA_SPIN_LOCK(PID_LIST_LOCK, &pid_list_lock);
+	LIST_DEL(&elem->list);
+	HA_SPIN_UNLOCK(PID_LIST_LOCK, &pid_list_lock);
+
+	if (!elem->exited)
+		kill(elem->pid, SIGTERM);
+
+	check = elem->t->context;
+	check->curpid = NULL;
+	pool_free(pool_head_pid_list, elem);
+}
+
+/* Called from inside SIGCHLD handler, SIGCHLD is blocked */
+static void pid_list_expire(pid_t pid, int status)
+{
+	struct pid_list *elem;
+
+	HA_SPIN_LOCK(PID_LIST_LOCK, &pid_list_lock);
+	list_for_each_entry(elem, &pid_list, list) {
+		if (elem->pid == pid) {
+			elem->t->expire = now_ms;
+			elem->status = status;
+			elem->exited = 1;
+			task_wakeup(elem->t, TASK_WOKEN_IO);
+			break;
+		}
+	}
+	HA_SPIN_UNLOCK(PID_LIST_LOCK, &pid_list_lock);
+}
+
+static void sigchld_handler(struct sig_handler *sh)
+{
+	pid_t pid;
+	int status;
+
+	while ((pid = waitpid(0, &status, WNOHANG)) > 0)
+		pid_list_expire(pid, status);
+}
+
+int init_pid_list(void)
+{
+	if (pool_head_pid_list != NULL)
+		/* Nothing to do */
+		return 0;
+
+	if (!signal_register_fct(SIGCHLD, sigchld_handler, SIGCHLD)) {
+		ha_alert("Failed to set signal handler for external health checks: %s. Aborting.\n",
+			 strerror(errno));
+		return 1;
+	}
+
+	pool_head_pid_list = create_pool("pid_list", sizeof(struct pid_list), MEM_F_SHARED);
+	if (pool_head_pid_list == NULL) {
+		ha_alert("Failed to allocate memory pool for external health checks: %s. Aborting.\n",
+			 strerror(errno));
+		return 1;
+	}
+
+	return 0;
+}
+
+/* helper macro to set an environment variable and jump to a specific label on failure. */
+#define EXTCHK_SETENV(check, envidx, value, fail) { if (extchk_setenv(check, envidx, value)) goto fail; }
+
+/*
+ * helper function to allocate enough memory to store an environment variable.
+ * It will also check that the environment variable is updatable, and silently
+ * fail if not.
+ */
+static int extchk_setenv(struct check *check, int idx, const char *value)
+{
+	int len, ret;
+	char *envname;
+	int vmaxlen;
+
+	if (idx < 0 || idx >= EXTCHK_SIZE) {
+		ha_alert("Illegal environment variable index %d. Aborting.\n", idx);
+		return 1;
+	}
+
+	envname = extcheck_envs[idx].name;
+	vmaxlen = extcheck_envs[idx].vmaxlen;
+
+	/* Check if the environment variable is already set, and silently reject
+	 * the update if this one is not updatable. */
+	if ((vmaxlen == EXTCHK_SIZE_EVAL_INIT) && (check->envp[idx]))
+		return 0;
+
+	/* Instead of sending NOT_USED, sending an empty value is preferable */
+	if (strcmp(value, "NOT_USED") == 0) {
+		value = "";
+	}
+
+	len = strlen(envname) + 1;
+	if (vmaxlen == EXTCHK_SIZE_EVAL_INIT)
+		len += strlen(value);
+	else
+		len += vmaxlen;
+
+	if (!check->envp[idx])
+		check->envp[idx] = malloc(len + 1);
+
+	if (!check->envp[idx]) {
+		ha_alert("Failed to allocate memory for the environment variable '%s'. Aborting.\n", envname);
+		return 1;
+	}
+	ret = snprintf(check->envp[idx], len + 1, "%s=%s", envname, value);
+	if (ret < 0) {
+		ha_alert("Failed to store the environment variable '%s'. Reason : %s. Aborting.\n", envname, strerror(errno));
+		return 1;
+	}
+	else if (ret > len) {
+		ha_alert("Environment variable '%s' was truncated. Aborting.\n", envname);
+		return 1;
+	}
+	return 0;
+}
+
+int prepare_external_check(struct check *check)
+{
+	struct server *s = check->server;
+	struct proxy *px = s->proxy;
+	struct listener *listener = NULL, *l;
+	int i;
+	const char *path = px->check_path ? px->check_path : DEF_CHECK_PATH;
+	char buf[256];
+
+	list_for_each_entry(l, &px->conf.listeners, by_fe)
+		/* Use the first INET, INET6 or UNIX listener */
+		if (l->addr.ss_family == AF_INET ||
+		    l->addr.ss_family == AF_INET6 ||
+		    l->addr.ss_family == AF_UNIX) {
+			listener = l;
+			break;
+		}
+
+	check->curpid = NULL;
+	check->envp = calloc((EXTCHK_SIZE + 1), sizeof(char *));
+	if (!check->envp) {
+		ha_alert("Failed to allocate memory for environment variables. Aborting\n");
+		goto err;
+	}
+
+	check->argv = calloc(6, sizeof(char *));
+	if (!check->argv) {
+		ha_alert("Starting [%s:%s] check: out of memory.\n", px->id, s->id);
+		goto err;
+	}
+
+	check->argv[0] = px->check_command;
+
+	if (!listener) {
+		check->argv[1] = strdup("NOT_USED");
+		check->argv[2] = strdup("NOT_USED");
+	}
+	else if (listener->addr.ss_family == AF_INET ||
+	    listener->addr.ss_family == AF_INET6) {
+		addr_to_str(&listener->addr, buf, sizeof(buf));
+		check->argv[1] = strdup(buf);
+		port_to_str(&listener->addr, buf, sizeof(buf));
+		check->argv[2] = strdup(buf);
+	}
+	else if (listener->addr.ss_family == AF_UNIX) {
+		const struct sockaddr_un *un;
+
+		un = (struct sockaddr_un *)&listener->addr;
+		check->argv[1] = strdup(un->sun_path);
+		check->argv[2] = strdup("NOT_USED");
+	}
+	else {
+		ha_alert("Starting [%s:%s] check: unsupported address family.\n", px->id, s->id);
+		goto err;
+	}
+
+	if (!check->argv[1] || !check->argv[2]) {
+		ha_alert("Starting [%s:%s] check: out of memory.\n", px->id, s->id);
+		goto err;
+	}
+
+	check->argv[3] = calloc(EXTCHK_SIZE_ADDR, sizeof(*check->argv[3]));
+	check->argv[4] = calloc(EXTCHK_SIZE_UINT, sizeof(*check->argv[4]));
+	if (!check->argv[3] || !check->argv[4]) {
+		ha_alert("Starting [%s:%s] check: out of memory.\n", px->id, s->id);
+		goto err;
+	}
+
+	addr_to_str(&s->addr, check->argv[3], EXTCHK_SIZE_ADDR);
+	if (s->addr.ss_family == AF_INET || s->addr.ss_family == AF_INET6)
+		snprintf(check->argv[4], EXTCHK_SIZE_UINT, "%u", s->svc_port);
+
+	for (i = 0; i < 5; i++) {
+		if (!check->argv[i]) {
+			ha_alert("Starting [%s:%s] check: out of memory.\n", px->id, s->id);
+			goto err;
+		}
+	}
+
+	EXTCHK_SETENV(check, EXTCHK_PATH, path, err);
+	/* Add proxy environment variables */
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_PROXY_NAME, px->id, err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_PROXY_ID, ultoa_r(px->uuid, buf, sizeof(buf)), err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_PROXY_ADDR, check->argv[1], err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_PROXY_PORT, check->argv[2], err);
+	/* Add server environment variables */
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_NAME, s->id, err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_ID, ultoa_r(s->puid, buf, sizeof(buf)), err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_ADDR, check->argv[3], err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_PORT, check->argv[4], err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_MAXCONN, ultoa_r(s->maxconn, buf, sizeof(buf)), err);
+	EXTCHK_SETENV(check, EXTCHK_HAPROXY_SERVER_CURCONN, ultoa_r(s->cur_sess, buf, sizeof(buf)), err);
+
+	/* Ensure that we don't leave any hole in check->envp */
+	for (i = 0; i < EXTCHK_SIZE; i++)
+		if (!check->envp[i])
+			EXTCHK_SETENV(check, i, "", err);
+
+	return 1;
+err:
+	if (check->envp) {
+		for (i = 0; i < EXTCHK_SIZE; i++)
+			free(check->envp[i]);
+		free(check->envp);
+		check->envp = NULL;
+	}
+
+	if (check->argv) {
+		for (i = 1; i < 5; i++)
+			free(check->argv[i]);
+		free(check->argv);
+		check->argv = NULL;
+	}
+	return 0;
+}
+
+/*
+ * establish a server health-check that makes use of a process.
+ *
+ * It can return one of :
+ *  - SF_ERR_NONE if everything's OK
+ *  - SF_ERR_RESOURCE if a system resource is lacking (eg: fd limits, ports, ...)
+ * Additionally, in the case of SF_ERR_RESOURCE, an emergency log will be emitted.
+ *
+ * Blocks and then unblocks SIGCHLD
+ */
+static int connect_proc_chk(struct task *t)
+{
+	char buf[256];
+	struct check *check = t->context;
+	struct server *s = check->server;
+	struct proxy *px = s->proxy;
+	int status;
+	pid_t pid;
+
+	status = SF_ERR_RESOURCE;
+
+	block_sigchld();
+
+	pid = fork();
+	if (pid < 0) {
+		ha_alert("Failed to fork process for external health check%s: %s. Aborting.\n",
+			 (global.tune.options & GTUNE_INSECURE_FORK) ?
+			 "" : " (likely caused by missing 'insecure-fork-wanted')",
+			 strerror(errno));
+		set_server_check_status(check, HCHK_STATUS_SOCKERR, strerror(errno));
+		goto out;
+	}
+	if (pid == 0) {
+		/* Child */
+		extern char **environ;
+		struct rlimit limit;
+		int fd;
+
+		/* close all FDs. Keep stdin/stdout/stderr in verbose mode */
+		fd = (global.mode & (MODE_QUIET|MODE_VERBOSE)) == MODE_QUIET ? 0 : 3;
+
+		my_closefrom(fd);
+
+		/* restore the initial FD limits */
+		limit.rlim_cur = rlim_fd_cur_at_boot;
+		limit.rlim_max = rlim_fd_max_at_boot;
+		if (setrlimit(RLIMIT_NOFILE, &limit) == -1) {
+			getrlimit(RLIMIT_NOFILE, &limit);
+			ha_warning("External check: failed to restore initial FD limits (cur=%u max=%u), using cur=%u max=%u\n",
+				   rlim_fd_cur_at_boot, rlim_fd_max_at_boot,
+				   (unsigned int)limit.rlim_cur, (unsigned int)limit.rlim_max);
+		}
+
+		environ = check->envp;
+
+		/* Update some environment variables and command args: curconn, server addr and server port */
+		extchk_setenv(check, EXTCHK_HAPROXY_SERVER_CURCONN, ultoa_r(s->cur_sess, buf, sizeof(buf)));
+
+		addr_to_str(&s->addr, check->argv[3], EXTCHK_SIZE_ADDR);
+		extchk_setenv(check, EXTCHK_HAPROXY_SERVER_ADDR, check->argv[3]);
+
+		*check->argv[4] = 0;
+		if (s->addr.ss_family == AF_INET || s->addr.ss_family == AF_INET6)
+			snprintf(check->argv[4], EXTCHK_SIZE_UINT, "%u", s->svc_port);
+		extchk_setenv(check, EXTCHK_HAPROXY_SERVER_PORT, check->argv[4]);
+
+		haproxy_unblock_signals();
+		execvp(px->check_command, check->argv);
+		ha_alert("Failed to exec process for external health check: %s. Aborting.\n",
+			 strerror(errno));
+		exit(-1);
+	}
+
+	/* Parent */
+	if (check->result == CHK_RES_UNKNOWN) {
+		if (pid_list_add(pid, t) != NULL) {
+			t->expire = tick_add(now_ms, MS_TO_TICKS(check->inter));
+
+			if (px->timeout.check && px->timeout.connect) {
+				int t_con = tick_add(now_ms, px->timeout.connect);
+				t->expire = tick_first(t->expire, t_con);
+			}
+			status = SF_ERR_NONE;
+			goto out;
+		}
+		else {
+			set_server_check_status(check, HCHK_STATUS_SOCKERR, strerror(errno));
+		}
+		kill(pid, SIGTERM); /* process creation error */
+	}
+	else
+		set_server_check_status(check, HCHK_STATUS_SOCKERR, strerror(errno));
+
+out:
+	unblock_sigchld();
+	return status;
+}
+
+/*
+ * manages a server health-check that uses an external process. Returns
+ * the time the task accepts to wait, or TIME_ETERNITY for infinity.
+ *
+ * Please do NOT place any return statement in this function and only leave
+ * via the out_unlock label.
+ */
+struct task *process_chk_proc(struct task *t, void *context, unsigned short state)
+{
+	struct check *check = context;
+	struct server *s = check->server;
+	int rv;
+	int ret;
+	int expired = tick_is_expired(t->expire, now_ms);
+
+	HA_SPIN_LOCK(SERVER_LOCK, &check->server->lock);
+	if (!(check->state & CHK_ST_INPROGRESS)) {
+		/* no check currently running */
+		if (!expired) /* woke up too early */
+			goto out_unlock;
+
+		/* we don't send any health-checks when the proxy is
+		 * stopped, the server should not be checked or the check
+		 * is disabled.
+		 */
+		if (((check->state & (CHK_ST_ENABLED | CHK_ST_PAUSED)) != CHK_ST_ENABLED) ||
+		    s->proxy->state == PR_STSTOPPED)
+			goto reschedule;
+
+		/* we'll initiate a new check */
+		set_server_check_status(check, HCHK_STATUS_START, NULL);
+
+		check->state |= CHK_ST_INPROGRESS;
+
+		ret = connect_proc_chk(t);
+		if (ret == SF_ERR_NONE) {
+			/* the process was forked, we allow up to min(inter,
+			 * timeout.connect) for it to report its status, but
+			 * only when timeout.check is set as it may be to short
+			 * for a full check otherwise.
+			 */
+			t->expire = tick_add(now_ms, MS_TO_TICKS(check->inter));
+
+			if (s->proxy->timeout.check && s->proxy->timeout.connect) {
+				int t_con = tick_add(now_ms, s->proxy->timeout.connect);
+				t->expire = tick_first(t->expire, t_con);
+			}
+			task_set_affinity(t, tid_bit);
+			goto reschedule;
+		}
+
+		/* here, we failed to start the check */
+
+		check->state &= ~CHK_ST_INPROGRESS;
+		check_notify_failure(check);
+
+		/* we allow up to min(inter, timeout.connect) for a connection
+		 * to establish but only when timeout.check is set
+		 * as it may be to short for a full check otherwise
+		 */
+		while (tick_is_expired(t->expire, now_ms)) {
+			int t_con;
+
+			t_con = tick_add(t->expire, s->proxy->timeout.connect);
+			t->expire = tick_add(t->expire, MS_TO_TICKS(check->inter));
+
+			if (s->proxy->timeout.check)
+				t->expire = tick_first(t->expire, t_con);
+		}
+	}
+	else {
+		/* there was a test running.
+		 * First, let's check whether there was an uncaught error,
+		 * which can happen on connect timeout or error.
+		 */
+		if (check->result == CHK_RES_UNKNOWN) {
+			/* good connection is enough for pure TCP check */
+			struct pid_list *elem = check->curpid;
+			int status = HCHK_STATUS_UNKNOWN;
+
+			if (elem->exited) {
+				status = elem->status; /* Save in case the process exits between use below */
+				if (!WIFEXITED(status))
+					check->code = -1;
+				else
+					check->code = WEXITSTATUS(status);
+				if (!WIFEXITED(status) || WEXITSTATUS(status))
+					status = HCHK_STATUS_PROCERR;
+				else
+					status = HCHK_STATUS_PROCOK;
+			} else if (expired) {
+				status = HCHK_STATUS_PROCTOUT;
+				ha_warning("kill %d\n", (int)elem->pid);
+				kill(elem->pid, SIGTERM);
+			}
+			set_server_check_status(check, status, NULL);
+		}
+
+		if (check->result == CHK_RES_FAILED) {
+			/* a failure or timeout detected */
+			check_notify_failure(check);
+		}
+		else if (check->result == CHK_RES_CONDPASS) {
+			/* check is OK but asks for stopping mode */
+			check_notify_stopping(check);
+		}
+		else if (check->result == CHK_RES_PASSED) {
+			/* a success was detected */
+			check_notify_success(check);
+		}
+		task_set_affinity(t, 1);
+		check->state &= ~CHK_ST_INPROGRESS;
+
+		pid_list_del(check->curpid);
+
+		rv = 0;
+		if (global.spread_checks > 0) {
+			rv = srv_getinter(check) * global.spread_checks / 100;
+			rv -= (int) (2 * rv * (ha_random32() / 4294967295.0));
+		}
+		t->expire = tick_add(now_ms, MS_TO_TICKS(srv_getinter(check) + rv));
+	}
+
+ reschedule:
+	while (tick_is_expired(t->expire, now_ms))
+		t->expire = tick_add(t->expire, MS_TO_TICKS(check->inter));
+
+ out_unlock:
+	HA_SPIN_UNLOCK(SERVER_LOCK, &check->server->lock);
+	return t;
+}
+
+/* Parses the "external-check" proxy keyword */
+int proxy_parse_extcheck(char **args, int section, struct proxy *curpx,
+                         struct proxy *defpx, const char *file, int line,
+                         char **errmsg)
+{
+	int cur_arg, ret = 0;
+
+	cur_arg = 1;
+	if (!*(args[cur_arg])) {
+		memprintf(errmsg, "missing argument after '%s'.\n", args[0]);
+		goto error;
+	}
+
+	if (strcmp(args[cur_arg], "command") == 0) {
+		if (too_many_args(2, args, errmsg, NULL))
+			goto error;
+		if (!*(args[cur_arg+1])) {
+			memprintf(errmsg, "missing argument after '%s'.", args[cur_arg]);
+			goto error;
+		}
+		free(curpx->check_command);
+		curpx->check_command = strdup(args[cur_arg+1]);
+	}
+	else if (strcmp(args[cur_arg], "path") == 0) {
+		if (too_many_args(2, args, errmsg, NULL))
+			goto error;
+		if (!*(args[cur_arg+1])) {
+			memprintf(errmsg, "missing argument after '%s'.", args[cur_arg]);
+			goto error;
+		}
+		free(curpx->check_path);
+		curpx->check_path = strdup(args[cur_arg+1]);
+	}
+	else {
+		memprintf(errmsg, "'%s' only supports 'command' and 'path'. but got '%s'.",
+			  args[0], args[1]);
+		goto error;
+	}
+
+	ret = (*errmsg != NULL); /* Handle warning */
+	return ret;
+
+error:
+	return -1;
+}
+
+int proxy_parse_external_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+				   const char *file, int line)
+{
+	int err_code = 0;
+
+	curpx->options2 &= ~PR_O2_CHK_ANY;
+	curpx->options2 |= PR_O2_EXT_CHK;
+	if (alertif_too_many_args_idx(0, 1, file, line, args, &err_code))
+		goto out;
+
+  out:
+	return err_code;
+}
+
+static struct cfg_kw_list cfg_kws = {ILH, {
+        { CFG_LISTEN, "external-check", proxy_parse_extcheck },
+        { 0, NULL, NULL },
+}};
+
+INITCALL1(STG_REGISTER, cfg_register_keywords, &cfg_kws);