diff --git a/doc/internals/api/initcalls.txt b/doc/internals/api/initcalls.txt
index 4829f500a..30d873720 100644
--- a/doc/internals/api/initcalls.txt
+++ b/doc/internals/api/initcalls.txt
@@ -114,6 +114,19 @@ make sure to respect this ordering when adding new ones.
   exit. See also hap_register_per_thread_alloc() for functions called before
   these ones.
 
+- void hap_register_pre_check(int (*fct)())
+
+  This adds a call to function <fct> to the list of functions to be called at
+  the step just before the configuration validity checks. This is useful when you
+  need to create things like it would have been done during the configuration
+  parsing and where the initialization should continue in the configuration
+  check.
+  It could be used for example to generate a proxy with multiple servers using
+  the configuration parser itself. At this step the trash buffers are allocated.
+  Threads are not yet started so no protection is required. The function is
+  expected to return non-zero on success, or zero on failure. A failure will make
+  the process emit a succinct error message and immediately exit.
+
 - void hap_register_post_check(int (*fct)())
 
   This adds a call to function <fct> to the list of functions to be called at
@@ -317,6 +330,10 @@ alphanumerically ordered:
   create_pool_callback() with these arguments at stage STG_POOL. Do not use it
   directly, use either DECLARE_POOL() or DECLARE_STATIC_POOL() instead.
 
+- REGISTER_PRE_CHECK(fct)
+
+  Registers a call to register_pre_check(fct) at stage STG_REGISTER.
+
 - REGISTER_POST_CHECK(fct)
 
   Registers a call to register_post_check(fct) at stage STG_REGISTER.
diff --git a/include/haproxy/init-t.h b/include/haproxy/init-t.h
index dee86f867..110171b05 100644
--- a/include/haproxy/init-t.h
+++ b/include/haproxy/init-t.h
@@ -6,6 +6,11 @@
 struct proxy;
 struct server;
 
+struct pre_check_fct {
+	struct list list;
+	int (*fct)();
+};
+
 struct post_check_fct {
 	struct list list;
 	int (*fct)();
diff --git a/include/haproxy/init.h b/include/haproxy/init.h
index 4e8f09e26..6e3047567 100644
--- a/include/haproxy/init.h
+++ b/include/haproxy/init.h
@@ -7,6 +7,7 @@
 struct proxy;
 struct server;
 
+extern struct list pre_check_list;
 extern struct list post_check_list;
 extern struct list post_proxy_check_list;
 extern struct list post_server_check_list;
@@ -18,6 +19,7 @@ extern struct list server_deinit_list;
 extern struct list per_thread_free_list;
 extern struct list per_thread_deinit_list;
 
+void hap_register_pre_check(int (*fct)());
 void hap_register_post_check(int (*fct)());
 void hap_register_post_proxy_check(int (*fct)(struct proxy *));
 void hap_register_post_server_check(int (*fct)(struct server *));
@@ -30,6 +32,10 @@ void hap_register_per_thread_init(int (*fct)());
 void hap_register_per_thread_deinit(void (*fct)());
 void hap_register_per_thread_free(void (*fct)());
 
+/* simplified way to declare a pre-check callback in a file */
+#define REGISTER_PRE_CHECK(fct) \
+	INITCALL1(STG_REGISTER, hap_register_pre_check, (fct))
+
 /* simplified way to declare a post-check callback in a file */
 #define REGISTER_POST_CHECK(fct) \
 	INITCALL1(STG_REGISTER, hap_register_post_check, (fct))
diff --git a/src/haproxy.c b/src/haproxy.c
index 0187bc641..f61a3abf9 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1891,6 +1891,7 @@ static void init(int argc, char **argv)
 	struct wordlist *wl;
 	struct proxy *px;
 	struct post_check_fct *pcf;
+	struct pre_check_fct *prcf;
 	int ideal_maxconn;
 
 	if (!init_trash_buffers(1)) {
@@ -2107,6 +2108,8 @@ static void init(int argc, char **argv)
 	/* destroy unreferenced defaults proxies  */
 	proxy_destroy_all_unref_defaults();
 
+	list_for_each_entry(prcf, &pre_check_list, list)
+		err_code |= prcf->fct();
 
 	err_code |= check_config_validity();
 	for (px = proxies_list; px; px = px->next) {
diff --git a/src/init.c b/src/init.c
index ad8066265..6367ac56f 100644
--- a/src/init.c
+++ b/src/init.c
@@ -4,6 +4,17 @@
 #include <haproxy/init.h>
 #include <haproxy/list.h>
 
+/* These functions are called just before a config validity check, which mean
+ * they are suited to use them in case we need to generate part of the
+ * configuration. It could be used for example to generate a proxy with
+ * multiple servers using the configuration parser itself. At this step the
+ * trash buffers are allocated.
+ * The functions must return 0 on success, or a combination
+ * of ERR_* flags (ERR_WARN, ERR_ABORT, ERR_FATAL, ...). The 2 latter cause
+ * and immediate exit, so the function must have emitted any useful error.
+ */
+struct list pre_check_list = LIST_HEAD_INIT(pre_check_list);
+
 /* These functions are called just after the point where the program exits
  * after a config validity check, so they are generally suited for resource
  * allocation and slow initializations that should be skipped during basic
@@ -73,6 +84,20 @@ struct list per_thread_free_list = LIST_HEAD_INIT(per_thread_free_list);
  * valgrind mostly happy. */
 struct list per_thread_deinit_list = LIST_HEAD_INIT(per_thread_deinit_list);
 
+/* used to register some initialization functions to call before the checks. */
+void hap_register_pre_check(int (*fct)())
+{
+	struct pre_check_fct *b;
+
+	b = calloc(1, sizeof(*b));
+	if (!b) {
+		fprintf(stderr, "out of memory\n");
+		exit(1);
+	}
+	b->fct = fct;
+	LIST_APPEND(&pre_check_list, &b->list);
+}
+
 /* used to register some initialization functions to call after the checks. */
 void hap_register_post_check(int (*fct)())
 {