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Add opentelemetry_resource_attr #566

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96622aa
Add opentelemetry_resource_attr
yuriolisa Jul 28, 2025
365bdfe
Add opentelemetry_resource_attr
yuriolisa Jul 28, 2025
29383cb
Update doc
yuriolisa Jul 28, 2025
8a0dfea
implement requested changes
yuriolisa Jul 28, 2025
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12 changes: 11 additions & 1 deletion instrumentation/nginx/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,9 @@ load_module /path/to/otel_ngx_module.so;

http {
opentelemetry_service_name "nginx-proxy";
opentelemetry_otlp_traces_endpoint "http://collector:4318/v1/traces"
opentelemetry_otlp_traces_endpoint "http://collector:4318/v1/traces";
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Copilot AI Jul 28, 2025

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This appears to be an unrelated formatting fix (adding missing semicolon) that should be mentioned in the PR description or handled in a separate commit.

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opentelemetry_resource_attr "service.version" "1.0.0";
opentelemetry_resource_attr "deployment.environment.name" "production";

server {
listen 80;
Expand Down Expand Up @@ -104,6 +106,14 @@ Service name for the nginx instance (default: `uknown:nginx`).
- **syntax**: `opentelemetry_service_name <name>`
- **block**: `http`

### `opentelemetry_resource_attr`

Adds a custom resource attribute to the trace provider. Resource attributes represent the entity producing telemetry data, e.g. `opentelemetry_resource_attr "service.version" "1.0.0"` or `opentelemetry_resource_attr "deployment.environment.name" "production"`.

- **required**: `false`
- **syntax**: `opentelemetry_resource_attr <key> <value>`
- **block**: `http`

### `opentelemetry_span_processor`

Chooses between simple and batch span processor (default: `batch`).
Expand Down
2 changes: 2 additions & 0 deletions instrumentation/nginx/src/agent_config.h
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#pragma once

#include <string>
#include <unordered_map>

extern "C" {
#include <ngx_core.h>
Expand Down Expand Up @@ -38,4 +39,5 @@ struct OtelNgxAgentConfig

std::string sampler = "parentbased_always_on";
double samplerRatio = 1.0;
std::unordered_map<std::string, std::string> resourceAttributes;
};
37 changes: 36 additions & 1 deletion instrumentation/nginx/src/otel_ngx_module.cpp
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Expand Up @@ -1051,6 +1051,21 @@ char* OtelNgxSetTracesSamplerRatio(ngx_conf_t* cf, ngx_command_t*, void*) {
return NGX_CONF_OK;
}

char* OtelNgxSetResourceAttr(ngx_conf_t* cf, ngx_command_t*, void*) {
OtelMainConf* otelMainConf = GetOtelMainConf(cf);

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Copilot AI Jul 28, 2025

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The function should validate that exactly 2 arguments are provided (key and value). Currently, if fewer than 2 arguments are passed, accessing values[2] could cause undefined behavior.

Suggested change
if (cf->args->nelts < 3) {
ngx_log_error(NGX_LOG_ERR, cf->log, 0, "opentelemetry: invalid number of arguments for resource attribute. Expected 2 arguments (key and value).");
return (char*)NGX_CONF_ERROR;
}

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ngx_str_t* values = (ngx_str_t*)cf->args->elts;
ngx_str_t* key = &values[1];
ngx_str_t* value = &values[2];

std::string strKey((const char*)key->data, key->len);
std::string strValue((const char*)value->data, value->len);
Comment on lines +1081 to +1082
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The key and value strings are constructed without null-termination validation. If key->data or value->data are not null-terminated within the specified length, this could lead to buffer overruns when used elsewhere.

Suggested change
std::string strKey((const char*)key->data, key->len);
std::string strValue((const char*)value->data, value->len);
std::string strKey;
std::string strValue;
{
std::vector<char> keyBuffer(key->data, key->data + key->len);
keyBuffer.push_back('\0'); // Ensure null-termination
strKey = std::string(keyBuffer.data());
}
{
std::vector<char> valueBuffer(value->data, value->data + value->len);
valueBuffer.push_back('\0'); // Ensure null-termination
strValue = std::string(valueBuffer.data());
}

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otelMainConf->agentConfig.resourceAttributes[strKey] = strValue;

return NGX_CONF_OK;
}

static char* OtelNgxSetCustomAttribute(ngx_conf_t* conf, ngx_command_t*, void* userConf) {
OtelNgxLocationConf* locConf = (OtelNgxLocationConf*)userConf;

Expand Down Expand Up @@ -1250,6 +1265,14 @@ static ngx_command_t kOtelNgxCommands[] = {
0,
nullptr,
},
{
ngx_string("opentelemetry_resource_attr"),
NGX_HTTP_MAIN_CONF | NGX_CONF_TAKE2,
OtelNgxSetResourceAttr,
NGX_HTTP_MAIN_CONF_OFFSET,
0,
nullptr,
},
#if (NGX_PCRE)
{
ngx_string("opentelemetry_sensitive_header_names"),
Expand Down Expand Up @@ -1372,10 +1395,22 @@ static ngx_int_t OtelNgxStart(ngx_cycle_t* cycle) {
}

auto processor = CreateProcessor(agentConf, std::move(exporter));

// Build resource attributes
opentelemetry::sdk::resource::ResourceAttributes resourceAttrs;
for (const auto& attr : agentConf->resourceAttributes) {
resourceAttrs[attr.first] = attr.second;
}

// Set service.name if not already provided via resource attributes
if (resourceAttrs.find("service.name") == resourceAttrs.end()) {
resourceAttrs["service.name"] = serviceName;
}

auto provider =
nostd::shared_ptr<opentelemetry::trace::TracerProvider>(new sdktrace::TracerProvider(
std::move(processor),
opentelemetry::sdk::resource::Resource::Create({{"service.name", serviceName}}),
opentelemetry::sdk::resource::Resource::Create(resourceAttrs),
std::move(sampler)));

opentelemetry::trace::Provider::SetTracerProvider(std::move(provider));
Expand Down
2 changes: 2 additions & 0 deletions instrumentation/nginx/test/conf/nginx.conf
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Expand Up @@ -7,6 +7,8 @@ http {
opentelemetry_service_name "nginx-proxy";
opentelemetry_otlp_traces_endpoint "http://collector:4318/v1/traces";
opentelemetry_span_processor "simple";
opentelemetry_resource_attr "service.version" "1.0.0";
opentelemetry_resource_attr "deployment.environment.name" "test";
opentelemetry_operation_name otel_test;
opentelemetry_ignore_paths ignored.php;
access_log stderr;
Expand Down
2 changes: 2 additions & 0 deletions instrumentation/nginx/test/instrumentation/test/instrumentation_test.exs
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Expand Up @@ -154,6 +154,8 @@ defmodule InstrumentationTest do
assert status == 200

assert attrib(resource, "service.name") == "nginx-proxy"
assert attrib(resource, "service.version") == "1.0.0"
assert attrib(resource, "deployment.environment.name") == "test"
end

test "HTTP upstream | span attributes", %{trace_file: trace_file} do
Expand Down