out_forward: Add a new option 'Empty_Shared_Key' (#1874)

Fluentd allows to use an empty string "" as a shared key. This means
that the following configuration is perfectly valid in Fluentd.

    <source>
      @type forward
      <security>
        shared_key ""
        self_hostname foo
      </security>
    </source>

The trouble is that Fluent Bit was being unable to connect to such
a Fluentd node, because Fluent Bit's configuration syntax did not
allow to specify an empty string.

This adds a new boolean option 'Empty_Shared_Key' that enables us to
circumvent the limitation, and should make Fluent Bit on par with
Fluentd.

Signed-off-by: Fujimoto Seiji <[email protected]>

plugins/out_forward/forward.c

@@ -628,8 +628,19 @@ static int forward_config_ha(const char *upstream_file,
  }
 
  /* Shared key */
+ tmp = flb_upstream_node_get_property("empty_shared_key", node);
+ if (tmp && flb_utils_bool(tmp)) {
+ fc->empty_shared_key = FLB_TRUE;
+ }
+ else {
+ fc->empty_shared_key = FLB_FALSE;
+ }
+
  tmp = flb_upstream_node_get_property("shared_key", node);
- if (tmp) {
+ if (fc->empty_shared_key == FLB_TRUE) {
+ fc->shared_key = flb_sds_create("");
+ }
+ else if (tmp) {
  fc->shared_key = flb_sds_create(tmp);
  }
  else {
@@ -755,10 +766,24 @@ static int forward_config_simple(struct flb_forward *ctx,
  flb_output_upstream_set(ctx->u, ins);
 
  /* Shared Key */
+ tmp = flb_output_get_property("empty_shared_key", ins);
+ if (tmp && flb_utils_bool(tmp)) {
+ fc->empty_shared_key = FLB_TRUE;
+ }
+ else {
+ fc->empty_shared_key = FLB_FALSE;
+ }
+
  tmp = flb_output_get_property("shared_key", ins);
- if (tmp) {
+ if (fc->empty_shared_key) {
+ fc->shared_key = flb_sds_create("");
+ }
+ else if (tmp) {
  fc->shared_key = flb_sds_create(tmp);
  }
+ else {
+ fc->shared_key = NULL;
+ }
 
  tmp = flb_output_get_property("username", ins);
  if (tmp) {

plugins/out_forward/forward.h

@@ -46,6 +46,7 @@ struct flb_forward_config {
  /* config */
  flb_sds_t shared_key; /* shared key */
  flb_sds_t self_hostname; /* hotname used in certificate */
+ int empty_shared_key; /* use an empty string as shared key */
  int require_ack_response; /* Require acknowledge for "chunk" */
  int send_options; /* send options in messages */