feat(trace): allow environment variables usage for url and serviceName

README.md

@@ -76,9 +76,9 @@ As with every [node installation](https://nodered.org/docs/user-guide/runtime/ad
 
 - Add OTEL node **once** (to any flow),
 - Setup the node:
-  - set OTEL [exporter](https://opentelemetry.io/docs/instrumentation/js/exporters/) url (example for Jaeger: `http://localhost:4318/v1/traces`),
+  - set OTEL [exporter](https://opentelemetry.io/docs/instrumentation/js/exporters/) url (example for Jaeger: `http://localhost:4318/v1/traces`). When left blank, the plugin will probe for [configuration via environment variables](https://opentelemetry.io/docs/languages/sdk-configuration/otlp-exporter/#otel_exporter_otlp_endpoint),
   - choose an OTLP transport protocol (`http/json` or `http/protobuf`),
-  - define a service name (will be displayed as span service),
+  - define a service name (will be displayed as span service; if the value of node is left blank, the plugin will probe for [configuration via environment variables](https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/)),
   - define an optional root span prefix (will be added in Node-RED root span name),
   - define nodes that should not send traces (using comma-separated list like `debug,catch`),
   - define nodes that should propagate [W3C trace context](https://www.w3.org/TR/trace-context/#design-overview) (in http request headers, using comma-separated list like `http request,my-custom-node`),

lib/opentelemetry-node.html

@@ -31,8 +31,8 @@
       value: '',
     },
     url: {
-      value: 'http://localhost:4318/v1/traces',
-      required: true,
+      value: '',
+      required: false,
       validate: function (v) {
         try {
           // eslint-disable-next-line no-new
@@ -44,8 +44,8 @@
       },
     },
     serviceName: {
-      value: 'Node-RED',
-      required: true,
+      value: '',
+      required: false,
     },
     protocol: {
       value: 'http',

lib/opentelemetry-node.js

@@ -1,7 +1,7 @@
 const os = require('os')
 const { name, version } = require('../package.json')
 const { trace, context, propagation, SpanKind, SpanStatusCode } = require('@opentelemetry/api')
-const { Resource } = require('@opentelemetry/resources')
+const { Resource, detectResourcesSync, envDetectorSync } = require('@opentelemetry/resources')
 const { ATTR_SERVICE_NAME, ATTR_HTTP_RESPONSE_STATUS_CODE, ATTR_URL_PATH, ATTR_SERVER_ADDRESS, ATTR_SERVER_PORT, ATTR_URL_SCHEME, ATTR_HTTP_REQUEST_METHOD, ATTR_CLIENT_ADDRESS, ATTR_USER_AGENT_ORIGINAL, ATTR_HTTP_REQUEST_HEADER } = require('@opentelemetry/semantic-conventions')
 // eslint-disable-next-line node/no-missing-require
 const { ATTR_HOST_NAME, ATTR_CODE_FUNCTION } = require('@opentelemetry/semantic-conventions/incubating')
@@ -12,6 +12,7 @@ const {
   CompositePropagator,
   W3CBaggagePropagator,
   W3CTraceContextPropagator,
+  merge,
 } = require('@opentelemetry/core')
 const { clearInterval } = require('timers')
 const { defaultTextMapGetter } = require('@opentelemetry/api')
@@ -249,7 +250,6 @@ function createSpan (tracer, msg, nodeDefinition, node, isNotTraced) {
       parentSpan = tracer.startSpan(_rootPrefix + spanName, {
         attributes: {
           [ATTR_IS_MESSAGE_CREATION]: true,
-          [ATTR_SERVICE_NAME]: nodeDefinition.type,
           ...commonAttributes,
         },
         kind,
@@ -478,26 +478,35 @@ module.exports = function (RED) {
     _attributeMappings = attributeMappings
 
     // check config
-    if (!url) {
-      this.status({ fill: 'red', shape: 'ring', text: 'invalid configuration' })
-      return
-    }
     const node = this
 
     // create tracer
     let spanProcessor
+    const traceExporterProps = url ? { url } : {}
     if (protocol === 'proto') {
       const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-proto')
-      spanProcessor = new BatchSpanProcessor(new OTLPTraceExporter({ url }))
+      spanProcessor = new BatchSpanProcessor(new OTLPTraceExporter(traceExporterProps))
     } else {
       const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-http')
-      spanProcessor = new BatchSpanProcessor(new OTLPTraceExporter({ url }))
+      spanProcessor = new BatchSpanProcessor(new OTLPTraceExporter(traceExporterProps))
     }
+
+    // Create OTEL resource, combining props passed via environment variables
+    // and those explicitly given in OTEL node UI
+    const explicitResource = new Resource(
+      serviceName
+        ? { [ATTR_SERVICE_NAME]: serviceName, [ATTR_HOST_NAME]: os.hostname() }
+        : { [ATTR_HOST_NAME]: os.hostname() },
+    )
+    const envResource = detectResourcesSync({ detectors: [envDetectorSync] })
+    const mergedResource = explicitResource.merge(envResource)
+
+    if (_isLogging) {
+      console.log('Initializing tracer provider with resource', mergedResource)
+    }
+
     const provider = new BasicTracerProvider({
-      resource: new Resource({
-        [ATTR_SERVICE_NAME]: serviceName,
-        [ATTR_HOST_NAME]: os.hostname(),
-      }),
+      resource: mergedResource,
       spanProcessors: [spanProcessor],
     })
     provider.register()