out_opentelemetry: Add resource attributes option

plugins/out_opentelemetry/opentelemetry.c

@@ -1030,6 +1030,12 @@ static struct flb_config_map config_map[] = {
                                              add_labels),
      "Adds a custom label to the metrics use format: 'add_label name value'"
     },
+    {
+     FLB_CONFIG_MAP_SLIST_1, "logs_resource_attributes_message_key", NULL,
+     FLB_CONFIG_MAP_MULT, FLB_TRUE, offsetof(struct opentelemetry_context,
+                                             ra_resource_attributes_message),
+     "Specify a resource attribute key"
+    },
     {
      FLB_CONFIG_MAP_STR, "http2", "off",
      0, FLB_TRUE, offsetof(struct opentelemetry_context, enable_http2),

plugins/out_opentelemetry/opentelemetry.h

@@ -138,6 +138,8 @@ struct opentelemetry_context {
     flb_sds_t logs_severity_number_message_key;
     struct flb_record_accessor *ra_severity_number_message;
 
+    struct mk_list *ra_resource_attributes_message;
+
     /* Number of logs to flush at a time */
     int batch_size;
 

plugins/out_opentelemetry/opentelemetry_conf.c

@@ -148,7 +148,43 @@ static int metadata_mp_accessor_create(struct opentelemetry_context *ctx)
     return 0;
 }
 
-static int config_add_labels(struct flb_output_instance *ins,
+/*
+ * config_ra_resource_attributes_message: validate the configured keys at init
+ * time. The actual key lookup at flush time reads ctx->ra_resource_attributes_message
+ * directly (config-map-managed pointer) to avoid per-worker context list issues.
+ */
+static int config_ra_resource_attributes_message(struct flb_output_instance *ins,
+                                                struct opentelemetry_context *ctx)
+{
+    struct mk_list *head;
+    struct flb_config_map_val *mv;
+    struct flb_slist_entry *k;
+
+    if (!ctx->ra_resource_attributes_message ||
+        mk_list_size(ctx->ra_resource_attributes_message) == 0) {
+        return 0;
+    }
+
+    flb_plg_debug(ins, "resource attributes: %d key(s) configured",
+                  mk_list_size(ctx->ra_resource_attributes_message));
+
+    /* validate each entry has exactly one value */
+    flb_config_map_foreach(head, mv, ctx->ra_resource_attributes_message) {
+        if (mk_list_size(mv->val.list) != 1) {
+            flb_plg_error(ins, "'logs_resource_attributes_message_key' expects a single key name, "
+                          "e.g: 'logs_resource_attributes_message_key service.name' "
+                          "(or '$service.name')");
+            return -1;
+        }
+
+        k = mk_list_entry_first(mv->val.list, struct flb_slist_entry, _head);
+        flb_plg_debug(ins, "resource attributes: registered key '%s'", k->str);
+    }
+
+    return 0;
+}
+
+static int config_log_body(struct flb_output_instance *ins,
                              struct opentelemetry_context *ctx)
 {
     struct mk_list *head;
@@ -294,7 +330,13 @@ struct opentelemetry_context *flb_opentelemetry_context_create(struct flb_output
     }
 
     /* Parse 'add_label' */
-    ret = config_add_labels(ins, ctx);
+    ret = config_log_body(ins, ctx);
+    if (ret == -1) {
+        flb_opentelemetry_context_destroy(ctx);
+        return NULL;
+    }
+
+    ret = config_ra_resource_attributes_message(ins, ctx);
     if (ret == -1) {
         flb_opentelemetry_context_destroy(ctx);
         return NULL;

plugins/out_opentelemetry/opentelemetry_logs.c

@@ -26,6 +26,7 @@
 #include <fluent-bit/flb_log_event_decoder.h>
 #include <fluent-bit/flb_ra_key.h>
 #include <fluent-bit/flb_gzip.h>
+#include <fluent-bit/flb_slist.h>
 
 #include <fluent-otel-proto/fluent-otel.h>
 
@@ -780,6 +781,163 @@ static int logs_flush_to_otel(struct opentelemetry_context *ctx, struct flb_even
     return ret;
 }
 
+/*
+ * For each key name in ctx->ra_resource_attributes_message_list, look it up in
+ * the msgpack message body and promote the value to an OTLP resource attribute.
+ */
+static void set_resource_attributes_from_message_body(
+    struct opentelemetry_context *ctx,
+    msgpack_object *body,
+    Opentelemetry__Proto__Resource__V1__Resource *resource)
+{
+    int i;
+    size_t key_len;
+    size_t map_key_len;
+    char *map_key_ptr;
+    struct mk_list *head;
+    struct flb_config_map_val *mv;
+    struct flb_slist_entry *entry;
+    const char *normalized_key;
+    msgpack_object_kv *kv;
+    Opentelemetry__Proto__Common__V1__KeyValue *attr;
+    Opentelemetry__Proto__Common__V1__KeyValue **tmp_attrs;
+
+    /*
+     * Use ctx->ra_resource_attributes_message directly — this is the pointer
+     * managed by the Fluent Bit config-map framework and is reliably available
+     * in every worker thread context, unlike an embedded mk_list copy.
+     */
+    if (!ctx->ra_resource_attributes_message ||
+        mk_list_size(ctx->ra_resource_attributes_message) == 0) {
+        return;
+    }
+
+    if (body == NULL || body->type != MSGPACK_OBJECT_MAP) {
+        return;
+    }
+
+    /* Iterate directly over the config-map-managed list */
+    flb_config_map_foreach(head, mv, ctx->ra_resource_attributes_message) {
+        if (mk_list_size(mv->val.list) != 1) {
+            continue;
+        }
+
+        entry = mk_list_entry_first(mv->val.list, struct flb_slist_entry, _head);
+        normalized_key = entry->str;
+        key_len = flb_sds_len(entry->str);
+
+        if (key_len == 0) {
+            continue;
+        }
+
+        /*
+         * Allow optional record accessor prefix so both "service.name" and
+         * "$service.name" are treated as the same map key.
+         */
+        if (key_len > 0 && normalized_key[0] == '$') {
+            normalized_key++;
+            key_len--;
+        }
+
+        /*
+         * Also tolerate bracket forms like $['service.name'] and
+         * $["service.name"] for literal keys.
+         */
+        if (key_len >= 4 && normalized_key[0] == '[') {
+            if ((normalized_key[1] == '\'' && normalized_key[key_len - 2] == '\'' &&
+                 normalized_key[key_len - 1] == ']') ||
+                (normalized_key[1] == '"' && normalized_key[key_len - 2] == '"' &&
+                 normalized_key[key_len - 1] == ']')) {
+                normalized_key += 2;
+                key_len -= 4;
+            }
+        }
+
+        if (key_len == 0) {
+            continue;
+        }
+
+        /* tolerate quoted key names like "service.name" or 'service.name' */
+        if (key_len >= 2) {
+            if ((normalized_key[0] == '"' && normalized_key[key_len - 1] == '"') ||
+                (normalized_key[0] == '\'' && normalized_key[key_len - 1] == '\'')) {
+                normalized_key++;
+                key_len -= 2;
+            }
+        }
+
+        if (key_len == 0) {
+            continue;
+        }
+
+        for (i = 0; i < body->via.map.size; i++) {
+            kv = &body->via.map.ptr[i];
+
+            if (kv->key.type == MSGPACK_OBJECT_STR) {
+                map_key_ptr = kv->key.via.str.ptr;
+                map_key_len = kv->key.via.str.size;
+            }
+            else if (kv->key.type == MSGPACK_OBJECT_BIN) {
+                map_key_ptr = (char *) kv->key.via.bin.ptr;
+                map_key_len = kv->key.via.bin.size;
+            }
+            else {
+                continue;
+            }
+
+            if (map_key_len != key_len) {
+                continue;
+            }
+
+            if (strncmp(map_key_ptr, normalized_key, key_len) != 0) {
+                continue;
+            }
+
+            /* Found the key — convert to OTLP KeyValue */
+            if (kv->key.type == MSGPACK_OBJECT_STR) {
+                attr = msgpack_kv_to_otlp_any_value(kv);
+            }
+            else {
+                attr = otlp_kvpair_value_initialize();
+                if (attr != NULL) {
+                    attr->key = flb_strndup(map_key_ptr, map_key_len);
+
+                    if (attr->key != NULL) {
+                        attr->value = msgpack_object_to_otlp_any_value(&kv->val);
+                    }
+
+                    if (attr->key == NULL || attr->value == NULL) {
+                        otlp_kvpair_destroy(attr);
+                        attr = NULL;
+                    }
+                }
+            }
+
+            if (!attr) {
+                flb_plg_warn(ctx->ins, "resource attributes: failed to convert key '%s' to OTLP KeyValue",
+                             entry->str);
+                break;
+            }
+
+            /* Grow the resource attributes array by one slot */
+            tmp_attrs = flb_realloc(resource->attributes,
+                                    (resource->n_attributes + 1) *
+                                    sizeof(Opentelemetry__Proto__Common__V1__KeyValue *));
+            if (!tmp_attrs) {
+                flb_plg_error(ctx->ins, "resource attributes: memory allocation failed for key '%s'",
+                              entry->str);
+                otlp_kvpair_destroy(attr);
+                break;
+            }
+
+            resource->attributes = tmp_attrs;
+            resource->attributes[resource->n_attributes] = attr;
+            resource->n_attributes++;
+            break;
+        }
+    }
+}
+
 static int set_resource_attributes(struct flb_record_accessor *ra,
                                    msgpack_object *map,
                                    Opentelemetry__Proto__Resource__V1__Resource *resource)
@@ -1021,6 +1179,18 @@ int otel_process_logs(struct flb_event_chunk *event_chunk,
 
     ret = FLB_OK;
     while (flb_log_event_decoder_next(decoder, &event) == FLB_EVENT_DECODER_SUCCESS) {
+        /*
+         * For standalone records (non-native OTLP groups), resource attributes
+         * promoted from message keys are record-specific. Force a fresh
+         * resource/scope context per record when this feature is enabled to
+         * avoid carrying stale values across subsequent log lines.
+         */
+        if (native_otel == FLB_FALSE &&
+            ctx->ra_resource_attributes_message &&
+            mk_list_size(ctx->ra_resource_attributes_message) > 0) {
+            resource_id = -1;
+            scope_id = -1;
+        }
         /* Check if the record is special (group) or a normal one */
         ret = flb_log_event_decoder_get_record_type(&event, &record_type);
         if (ret != 0) {
@@ -1131,6 +1301,9 @@ int otel_process_logs(struct flb_event_chunk *event_chunk,
                 /* group body: $schema_url */
                 set_resource_schema_url(ctx->ra_resource_schema_url, event.body, resource_log);
 
+                /* message body: promote configured keys to resource attributes */
+                set_resource_attributes_from_message_body(ctx, event.body, resource_log->resource);
+
                 /* prepare the scopes */
                 if (!resource_log->scope_logs) {
                     if (max_scopes_limit > 0) {