Add feature custom resource attributes

src/batch_exporter.hpp

@@ -10,6 +10,11 @@
 #include "trace_context.hpp"
 #include "trace_service_client.hpp"
 
+struct ResourceAttr {
+    ngx_str_t name;
+    ngx_http_complex_value_t value;
+};
+
 class BatchExporter {
 public:
     typedef TraceServiceClient::Request Request;
@@ -112,7 +117,7 @@ public:
     };
 
     BatchExporter(StrView target,
-            size_t batchSize, size_t batchCount, StrView serviceName) :
+            size_t batchSize, size_t batchCount, StrView serviceName, ngx_array_t customResourceAttrs) :
         batchSize(batchSize), client(std::string(target))
     {
         free.reserve(batchCount);
@@ -124,6 +129,15 @@ public:
             attr->set_key("service.name");
             attr->mutable_value()->set_string_value(std::string(serviceName));
 
+            auto attrs = (ResourceAttr*)customResourceAttrs.elts;
+            for (ngx_uint_t i = 0; i < customResourceAttrs.nelts; i++) {
+                attr = resourceSpans->mutable_resource()->add_attributes();
+                StrView value = StrView((char*)attrs[i].value.value.data, attrs[i].value.value.len);
+                StrView name = StrView((char*)attrs[i].name.data, attrs[i].name.len);
+                attr->set_key(std::string(name));
+                attr->mutable_value()->set_string_value(std::string(value));
+            }
+
             auto scopeSpans = resourceSpans->add_scope_spans();
             scopeSpans->mutable_scope()->set_name("nginx");
             scopeSpans->mutable_scope()->set_version(NGINX_VERSION);

src/http_module.cpp

@@ -22,6 +22,7 @@ struct MainConf {
     size_t batchCount;
 
     ngx_str_t serviceName;
+    ngx_array_t resourceAttrs;
 };
 
 struct SpanAttr {
@@ -39,6 +40,7 @@ struct LocationConf {
 
 char* setExporter(ngx_conf_t* cf, ngx_command_t* cmd, void* conf);
 char* addSpanAttr(ngx_conf_t* cf, ngx_command_t* cmd, void* conf);
+char* addResourceAttrs(ngx_conf_t* cf, ngx_command_t* cmd, void* conf);
 
 namespace Propagation {
 
@@ -68,6 +70,12 @@ ngx_command_t gCommands[] = {
       NGX_HTTP_MAIN_CONF_OFFSET,
       offsetof(MainConf, serviceName) },
     
+    { ngx_string("otel_resource_attr"),
+      NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_NOARGS,
+      addResourceAttrs,
+      NGX_HTTP_MAIN_CONF_OFFSET,
+      offsetof(MainConf, resourceAttrs) },
+
     { ngx_string("otel_trace"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
       ngx_http_set_complex_value_slot,
@@ -455,6 +463,7 @@ void addCustomAttrs(BatchExporter::Span& span, ngx_http_request_t* r)
     }
 }
 
+
 ngx_int_t onRequestEnd(ngx_http_request_t* r)
 {
     auto ctx = getOtelCtx(r);
@@ -540,7 +549,9 @@ ngx_int_t initWorkerProcess(ngx_cycle_t* cycle)
             toStrView(mcf->endpoint),
             mcf->batchSize,
             mcf->batchCount,
-            toStrView(mcf->serviceName)));
+            toStrView(mcf->serviceName),
+            mcf->resourceAttrs
+            ));
     } catch (const std::exception& e) {
         ngx_log_error(NGX_LOG_CRIT, cycle->log, 0,
             "OTel worker init error: %s", e.what());
@@ -705,6 +716,58 @@ char* addSpanAttr(ngx_conf_t* cf, ngx_command_t* cmd, void* conf)
     return NGX_CONF_OK;
 }
 
+char* addResourceAttr(ngx_conf_t* cf, ngx_command_t* cmd, void* conf) {
+    auto mcf = (MainConf*)conf;
+
+    if (mcf->resourceAttrs.elts == NULL && ngx_array_init(&mcf->resourceAttrs,
+            cf->pool, 4, sizeof(ResourceAttr)) != NGX_OK) {
+        return (char*)NGX_CONF_ERROR;
+    }
+
+    auto attr = (ResourceAttr*)ngx_array_push(&mcf->resourceAttrs);
+    if (attr == NULL) {
+        return (char*)NGX_CONF_ERROR;
+    }
+
+    auto args = (ngx_str_t*)cf->args->elts;
+
+    attr->name = args[0];
+
+    ngx_http_compile_complex_value_t ccv = { cf, &args[1], &attr->value };
+    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
+        return (char*)NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
+char* addResourceAttrs(ngx_conf_t* cf, ngx_command_t* cmd, void* conf)
+{
+    auto mcf = (MainConf*)conf;
+
+    if (mcf->resourceAttrs.elts == NULL && ngx_array_init(&mcf->resourceAttrs,
+        cf->pool, 4, sizeof(ResourceAttr)) != NGX_OK) {
+            return (char*)NGX_CONF_ERROR;
+        }
+    
+    auto cfCopy = *cf;
+
+    cfCopy.handler = addResourceAttr;
+    cfCopy.handler_conf = mcf;
+    auto rv = ngx_conf_parse(&cfCopy, NULL);
+    if (rv != NGX_CONF_OK) {
+        return rv;
+    }
+
+    if (mcf->endpoint.len == 0) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+            "\"otel_exporter\" requires \"endpoint\"");
+        return (char*)NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
 template <class Id>
 ngx_int_t hexIdVar(ngx_http_request_t* r, ngx_http_variable_value_t* v,
     uintptr_t data)