MINOR: http_ext/7239: warn the user when fetch is not available
http option forwarded (rfc7239) supports sample expressions when
configuring 'host', 'for' and 'by' parameters.
However, since we are in a http-backend-only context, right after http
header is processed, we have a limited resolution scope for the sample
expression provided by the user.
To prevent any confusion, a warning is emitted when parsing the option
if the user relies on a sample expression (more precisely a fetch) which
would yield unexpected results at runtime when processing the option.
diff --git a/src/http_ext.c b/src/http_ext.c
index 4a9a0b0..f2e3781 100644
--- a/src/http_ext.c
+++ b/src/http_ext.c
@@ -1143,6 +1143,19 @@
ha_free(&err);
cfgerr++;
}
+ else if (!(cur_expr->fetch->val & SMP_VAL_BE_HRQ_HDR)) {
+ /* fetch not available in this context: sample expr is resolved
+ * within backend right after headers are processed.
+ * (in http_process_request())
+ * -> we simply warn the user about the misuse
+ */
+ ha_warning("%s '%s' [%s:%d]: in 'option forwarded' sample expression '%s' : "
+ "some args extract information from '%s', "
+ "none of which is available here.\n",
+ proxy_type_str(curproxy), curproxy->id,
+ curproxy->http.fwd.c_file, curproxy->http.fwd.c_line,
+ *expr_str, sample_ckp_names(cur_expr->fetch->use));
+ }
/* post parsing individual expr cleanup */
ha_free(expr_str);