processor_content_modifier: add support for Metrics processing

plugins/processor_content_modifier/CMakeLists.txt

@@ -1,7 +1,10 @@
 set(src
   cm_config.c
   cm_logs.c
+  cm_metrics.c
   cm_traces.c
+  cm_opentelemetry.c
+  cm_utils.c
   cm.c
   )
 

plugins/processor_content_modifier/cm.c

@@ -98,6 +98,24 @@ static int cb_process_traces(struct flb_processor_instance *ins,
 
 }
 
+static int cb_process_metrics(struct flb_processor_instance *ins,
+                              struct cmt *in_cmt,
+                              struct cmt **out_cmt,
+                              const char *tag,
+                              int tag_len)
+{
+    int ret;
+    struct content_modifier_ctx *ctx;
+
+    if (!ins->context) {
+        return FLB_PROCESSOR_FAILURE;
+    }
+    ctx = ins->context;
+
+    ret = cm_metrics_process(ins, ctx, in_cmt, out_cmt, tag, tag_len);
+    return ret;
+}
+
 static struct flb_config_map config_map[] = {
     {
         FLB_CONFIG_MAP_STR, "context", NULL,
@@ -144,7 +162,7 @@ struct flb_processor_plugin processor_content_modifier_plugin = {
     .description        = "Modify the content of Logs, Metrics and Traces",
     .cb_init            = cb_init,
     .cb_process_logs    = cb_process_logs,
-    .cb_process_metrics = NULL,
+    .cb_process_metrics = cb_process_metrics,
     .cb_process_traces  = cb_process_traces,
     .cb_exit            = cb_exit,
     .config_map         = config_map,

plugins/processor_content_modifier/cm.h

@@ -116,5 +116,10 @@ int cm_traces_process(struct flb_processor_instance *ins,
                       struct ctrace *traces_context,
                       const char *tag, int tag_len);
 
+int cm_metrics_process(struct flb_processor_instance *ins,
+                       struct content_modifier_ctx *ctx,
+                       struct cmt *in_cmt,
+                       struct cmt **out_cmt,
+                       const char *tag, int tag_len);
 
 #endif

plugins/processor_content_modifier/cm_config.c

@@ -218,6 +218,53 @@ static int set_context(struct content_modifier_ctx *ctx)
                  strcasecmp(ctx->context_str, "attributes") == 0) {
             context = CM_CONTEXT_METRIC_LABELS;
         }
+
+        /*
+         * OpenTelemetry contexts
+         * ----------------------
+         */
+        else if (strcasecmp(ctx->context_str, "otel_resource_attributes") == 0) {
+            context = CM_CONTEXT_OTEL_RESOURCE_ATTR;
+        }
+        else if (strcasecmp(ctx->context_str, "otel_scope_attributes") == 0) {
+            context = CM_CONTEXT_OTEL_SCOPE_ATTR;
+        }
+        else if (strcasecmp(ctx->context_str, "otel_scope_name") == 0) {
+            /*
+             * scope name is restricted to specific actions, make sure the user
+             * cannot messed it up
+             *
+             *   action              allowed ?
+             *   -----------------------------
+             *   CM_ACTION_INSERT       Yes
+             *   CM_ACTION_UPSERT       Yes
+             *   CM_ACTION_DELETE       Yes
+             *   CM_ACTION_RENAME        No
+             *   CM_ACTION_HASH         Yes
+             *   CM_ACTION_EXTRACT       No
+             *   CM_ACTION_CONVERT       No
+             */
+
+            if (ctx->action_type == CM_ACTION_RENAME ||
+                ctx->action_type == CM_ACTION_EXTRACT ||
+                ctx->action_type == CM_ACTION_CONVERT) {
+                flb_plg_error(ctx->ins, "action '%s' is not allowed for context '%s'",
+                              ctx->action_str, ctx->context_str);
+                return -1;
+            }
+
+            /* check that 'name' is the key set */
+            if (!ctx->key) {
+                ctx->key = flb_sds_create("name");
+            }
+            else if (strcasecmp(ctx->key, "name") != 0) {
+                flb_plg_error(ctx->ins, "context '%s' requires the name of the key to be 'name', no '%s'",
+                              ctx->context_str, ctx->key);
+                return -1;
+            }
+
+            context = CM_CONTEXT_OTEL_SCOPE_NAME;
+        }
         else {
             flb_plg_error(ctx->ins, "unknown metrics context '%s'", ctx->context_str);
             return -1;