support url-encoded OTEL_EXPORTER_OTLP_HEADERS values (#1242)

Per a recent spec clarification in open-telemetry/opentelemetry-specification#3832 OTLP
headers should support url-encoded header values.

Co-authored-by: Tobias Bachert <[email protected]>

Author: brettmc

LogsExporterFactory.php

@@ -44,10 +44,7 @@ private function buildTransport(string $protocol): TransportInterface
     {
         $endpoint = $this->getEndpoint($protocol);
 
-        $headers = Configuration::has(Variables::OTEL_EXPORTER_OTLP_LOGS_HEADERS)
-            ? Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_LOGS_HEADERS)
-            : Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_HEADERS);
-        $headers += OtlpUtil::getUserAgentHeader();
+        $headers = OtlpUtil::getHeaders(Signals::LOGS);
         $compression = $this->getCompression();
 
         $factoryClass = Registry::transportFactory($protocol);

MetricExporterFactory.php

@@ -51,10 +51,7 @@ private function buildTransport(string $protocol): TransportInterface
          */
         $endpoint = $this->getEndpoint($protocol);
 
-        $headers = Configuration::has(Variables::OTEL_EXPORTER_OTLP_METRICS_HEADERS)
-            ? Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_METRICS_HEADERS)
-            : Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_HEADERS);
-        $headers += OtlpUtil::getUserAgentHeader();
+        $headers = OtlpUtil::getHeaders(Signals::METRICS);
         $compression = $this->getCompression();
 
         $factoryClass = Registry::transportFactory($protocol);

OtlpUtil.php

@@ -5,6 +5,8 @@
 namespace OpenTelemetry\Contrib\Otlp;
 
 use OpenTelemetry\API\Signals;
+use OpenTelemetry\SDK\Common\Configuration\Configuration;
+use OpenTelemetry\SDK\Common\Configuration\Variables;
 use OpenTelemetry\SDK\Resource\Detectors\Sdk;
 use OpenTelemetry\SemConv\ResourceAttributes;
 use UnexpectedValueException;
@@ -20,6 +22,11 @@ class OtlpUtil
         Signals::METRICS => '/opentelemetry.proto.collector.metrics.v1.MetricsService/Export',
         Signals::LOGS => '/opentelemetry.proto.collector.logs.v1.LogsService/Export',
     ];
+    private const HEADER_VARS = [
+        Signals::TRACE => Variables::OTEL_EXPORTER_OTLP_TRACES_HEADERS,
+        Signals::METRICS => Variables::OTEL_EXPORTER_OTLP_METRICS_HEADERS,
+        Signals::LOGS => Variables::OTEL_EXPORTER_OTLP_LOGS_HEADERS,
+    ];
 
     public static function method(string $signal): string
     {
@@ -30,6 +37,16 @@ public static function method(string $signal): string
         return self::METHODS[$signal];
     }
 
+    public static function getHeaders(string $signal): array
+    {
+        $headers = Configuration::has(self::HEADER_VARS[$signal]) ?
+            Configuration::getMap(self::HEADER_VARS[$signal]) :
+            Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_HEADERS);
+        $headers += self::getUserAgentHeader();
+
+        return array_map('rawurldecode', $headers);
+    }
+
     /**
      * @link https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#user-agent
      */

SpanExporterFactory.php

@@ -47,7 +47,7 @@ private function buildTransport(): TransportInterface
         $protocol = $this->getProtocol();
         $contentType = Protocols::contentType($protocol);
         $endpoint = $this->getEndpoint($protocol);
-        $headers = $this->getHeaders();
+        $headers = OtlpUtil::getHeaders(Signals::TRACE);
         $compression = $this->getCompression();
 
         $factoryClass = Registry::transportFactory($protocol);
@@ -78,15 +78,6 @@ private function getEndpoint(string $protocol): string
         return HttpEndpointResolver::create()->resolveToString($endpoint, Signals::TRACE);
     }
 
-    private function getHeaders(): array
-    {
-        $headers = Configuration::has(Variables::OTEL_EXPORTER_OTLP_TRACES_HEADERS) ?
-            Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_TRACES_HEADERS) :
-            Configuration::getMap(Variables::OTEL_EXPORTER_OTLP_HEADERS);
-
-        return $headers + OtlpUtil::getUserAgentHeader();
-    }
-
     private function getCompression(): string
     {
         return Configuration::has(Variables::OTEL_EXPORTER_OTLP_TRACES_COMPRESSION) ?