From 8562d0d510d133eac0dcd40376962bd1a214a9ba Mon Sep 17 00:00:00 2001
From: leo108 <root@leo108.com>
Date: Mon, 10 Oct 2022 06:17:43 +0800
Subject: [PATCH] Grpc metadata value must be an array (#839)

---
 src/Contrib/OtlpGrpc/Exporter.php             | 21 ++++++++++++++++---
 .../Contrib/OtlpGrpc/OTLPGrpcExporterTest.php |  8 +++----
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/Contrib/OtlpGrpc/Exporter.php b/src/Contrib/OtlpGrpc/Exporter.php
index 218ef0dc8..e8db779d5 100644
--- a/src/Contrib/OtlpGrpc/Exporter.php
+++ b/src/Contrib/OtlpGrpc/Exporter.php
@@ -67,9 +67,9 @@ public function __construct(
             $this->getIntFromEnvironment(Env::OTEL_EXPORTER_OTLP_TRACES_TIMEOUT, $timeout) :
             $this->getIntFromEnvironment(Env::OTEL_EXPORTER_OTLP_TIMEOUT, $timeout);
 
-        $this->metadata = $this->hasEnvironmentVariable(Env::OTEL_EXPORTER_OTLP_TRACES_HEADERS) ?
+        $this->metadata = self::transformToGrpcMetadata($this->hasEnvironmentVariable(Env::OTEL_EXPORTER_OTLP_TRACES_HEADERS) ?
             $this->getMapFromEnvironment(Env::OTEL_EXPORTER_OTLP_TRACES_HEADERS, $headers) :
-            $this->getMapFromEnvironment(Env::OTEL_EXPORTER_OTLP_HEADERS, $headers);
+            $this->getMapFromEnvironment(Env::OTEL_EXPORTER_OTLP_HEADERS, $headers));
 
         $opts = $this->getClientOptions();
 
@@ -160,8 +160,12 @@ protected function doExport(iterable $spans): bool
 
     public function setHeader($key, $value): void
     {
-        // metadata is supposed to be key-value pairs
+        // metadata is supposed to be key-value pairs and the value must be an array
         // @see https://grpc.io/docs/what-is-grpc/core-concepts/#metadata
+        if (!is_array($value)) {
+            $value = [$value];
+        }
+
         $this->metadata[$key] = $value;
     }
 
@@ -190,4 +194,15 @@ public static function fromConnectionString(string $endpointUrl = null, string $
     {
         return is_string($endpointUrl) ? new Exporter($endpointUrl) :  new Exporter();
     }
+
+    private static function transformToGrpcMetadata(array $metadata): array
+    {
+        foreach ($metadata as $key => $value) {
+            if (!is_array($value)) {
+                $metadata[$key] = [$value];
+            }
+        }
+
+        return $metadata;
+    }
 }
diff --git a/tests/Unit/Contrib/OtlpGrpc/OTLPGrpcExporterTest.php b/tests/Unit/Contrib/OtlpGrpc/OTLPGrpcExporterTest.php
index 3fe9764b6..b5fb6ef4f 100644
--- a/tests/Unit/Contrib/OtlpGrpc/OTLPGrpcExporterTest.php
+++ b/tests/Unit/Contrib/OtlpGrpc/OTLPGrpcExporterTest.php
@@ -107,7 +107,7 @@ public function test_set_headers_with_environment_variables(): void
 
         $exporter = new Exporter();
 
-        $this->assertEquals(['x-aaa' => 'foo', 'x-bbb' => 'barf'], $exporter->getHeaders());
+        $this->assertEquals(['x-aaa' => ['foo'], 'x-bbb' => ['barf']], $exporter->getHeaders());
     }
 
     public function test_set_header(): void
@@ -116,18 +116,18 @@ public function test_set_header(): void
         $exporter->setHeader('foo', 'bar');
         $headers = $exporter->getHeaders();
         $this->assertArrayHasKey('foo', $headers);
-        $this->assertEquals('bar', $headers['foo']);
+        $this->assertEquals(['bar'], $headers['foo']);
     }
 
     public function test_set_headers_in_constructor(): void
     {
         $exporter = new Exporter('localhost:4317', true, '', 'x-aaa=foo,x-bbb=bar');
 
-        $this->assertEquals(['x-aaa' => 'foo', 'x-bbb' => 'bar'], $exporter->getHeaders());
+        $this->assertEquals(['x-aaa' => ['foo'], 'x-bbb' => ['bar']], $exporter->getHeaders());
 
         $exporter->setHeader('key', 'value');
 
-        $this->assertEquals(['x-aaa' => 'foo', 'x-bbb' => 'bar', 'key' => 'value'], $exporter->getHeaders());
+        $this->assertEquals(['x-aaa' => ['foo'], 'x-bbb' => ['bar'], 'key' => ['value']], $exporter->getHeaders());
     }
 
     private function isInsecure(Exporter $exporter) : bool