[Monolog] Add option to directly assign context elements as attributes

src/Logs/Monolog/README.md

@@ -74,3 +74,75 @@ $logger = new \Monolog\Logger(
 );
 $logger->info('hello world');
 ```
+
+### Attributes Mode
+
+This OpenTelemetry handler will convert any `context` array or `extras` array in the `Monolog\LogRecord` to `OpenTelemetry\API\Logs\LogRecord`
+attributes. There are two options for handling conflicts between the classes.
+
+_Note that exceptions have special handling in both the PSR-3 spec and the OpenTelemetry spec. If a PHP `Throwable` is included in the `context`_
+_array with a key of `exception`, it will be added as `exception.` attributes to the OpenTelemetry Log Record._
+
+By default, the attribute keys will be `context` and `extras` with JSON encoded arrays, along with `context.` and `extras.` prefixed keys with the
+individual array entries, which will also be JSON encoded if they are not scalar values. Example:
+
+```php
+new Monolog\LogRecord(
+    ...,
+    context: [
+        'foo' => 'bar',
+        'obj' => new stdClass(),
+    ],
+    extras: [
+        'foo' => 'bar',
+        'baz' => 'bat',
+    ]
+);
+
+/**
+ * becomes:
+ *
+ * OpenTelemetry\API\Logs\LogRecord (
+ *     ...,
+ *     attributes => array (
+ *         context => '{"foo":"bar","obj":{}}'
+ *         context.foo => 'bar'
+ *         context.obj => '{}'
+ *         extras => '{"foo":"bar","baz":"bat"}'
+ *         extras.foo => 'bar'
+ *         extras.baz => 'bat'
+ *      )
+ * )
+ */
+```
+
+Alternatively, if your `context` and `extras` keys do not conflict with OpenTelemetry Semantic Conventions for Attribute keys, _and_ all your values
+are scalar, you can set `OTEL_PHP_MONOLOG_ATTRIB_MODE=otel` and they will be sent directly as Attributes. Example:
+
+```php
+new Monolog\LogRecord(
+    ...,
+    context: [
+        'myapp.data.foo' => 'bar',
+        'myapp.data.baz' => 'bat',
+    ],
+    extras: [
+        'server.address' => 'example.com',
+        'server.port' => 80,
+    ]
+);
+
+/**
+ * becomes:
+ *
+ * OpenTelemetry\API\Logs\LogRecord (
+ *     ...,
+ *     attributes => array (
+ *         myapp.data.foo => 'bar'
+ *         myapp.data.baz => 'bat'
+ *         server.address => 'example.com'
+ *         server.port => 80
+ *      )
+ * )
+ */
+```

src/Logs/Monolog/src/Handler.php

@@ -8,10 +8,25 @@
 use Monolog\Formatter\FormatterInterface;
 use Monolog\Formatter\NormalizerFormatter;
 use Monolog\Handler\AbstractProcessingHandler;
+use OpenTelemetry\API\Instrumentation\ConfigurationResolver;
 use OpenTelemetry\API\Logs as API;
+use OpenTelemetry\SDK\Common\Exception\StackTraceFormatter;
+use OpenTelemetry\SemConv\Attributes\ExceptionAttributes;
+
+use Throwable;
 
 class Handler extends AbstractProcessingHandler
 {
+    public const OTEL_PHP_MONOLOG_ATTRIB_MODE = 'OTEL_PHP_MONOLOG_ATTRIB_MODE';
+    public const MODE_PSR3 = 'psr3';
+    public const MODE_OTEL = 'otel';
+    private const MODES = [
+        self::MODE_PSR3,
+        self::MODE_OTEL,
+    ];
+    public const DEFAULT_MODE = self::MODE_PSR3;
+    private static string $mode;
+
     /** @var API\LoggerInterface[] */
     private array $loggers = [];
     private API\LoggerProviderInterface $loggerProvider;
@@ -23,6 +38,7 @@ public function __construct(API\LoggerProviderInterface $loggerProvider, $level,
     {
         parent::__construct($level, $bubble);
         $this->loggerProvider = $loggerProvider;
+        self::$mode = self::getMode();
     }
 
     protected function getLogger(string $channel): API\LoggerInterface
@@ -39,10 +55,6 @@ protected function getDefaultFormatter(): FormatterInterface
         return new NormalizerFormatter();
     }
 
-    /**
-     * @phan-suppress PhanTypeMismatchArgument
-     * @psalm-suppress InvalidOperand
-     */
     protected function write($record): void
     {
         $formatted = $record['formatted'];
@@ -53,10 +65,51 @@ protected function write($record): void
             ->setBody($formatted['message'])
         ;
         foreach (['context', 'extra'] as $key) {
-            if (isset($formatted[$key]) && count($formatted[$key]) > 0) {
+            if (self::$mode === self::MODE_PSR3 && isset($formatted[$key]) && count($formatted[$key]) > 0) {
                 $logRecord->setAttribute($key, $formatted[$key]);
             }
+            if (isset($record[$key]) && $record[$key] !== []) {
+                foreach ($record[$key] as $attributeName => $attribute) {
+                    if (
+                        $key === 'context'
+                        && $attributeName === 'exception'
+                        && $attribute instanceof Throwable
+                    ) {
+                        $logRecord->setAttribute(ExceptionAttributes::EXCEPTION_TYPE, $attribute::class);
+                        $logRecord->setAttribute(ExceptionAttributes::EXCEPTION_MESSAGE, $attribute->getMessage());
+                        $logRecord->setAttribute(ExceptionAttributes::EXCEPTION_STACKTRACE, StackTraceFormatter::format($attribute));
+
+                        continue;
+                    }
+                    switch (self::$mode) {
+                        case self::MODE_PSR3:
+                            if (!is_scalar($attribute)) {
+                                $attribute = json_encode($attribute);
+                            }
+                            $logRecord->setAttribute(sprintf('%s.%s', $key, $attributeName), $attribute);
+
+                            break;
+                        case self::MODE_OTEL:
+                            $logRecord->setAttribute($attributeName, $attribute);
+
+                            break;
+                    }
+                }
+            }
         }
         $this->getLogger($record['channel'])->emit($logRecord);
     }
+
+    private static function getMode(): string
+    {
+        $resolver = new ConfigurationResolver();
+        if ($resolver->has(self::OTEL_PHP_MONOLOG_ATTRIB_MODE)) {
+            $val = $resolver->getString(self::OTEL_PHP_MONOLOG_ATTRIB_MODE);
+            if ($val && in_array($val, self::MODES)) {
+                return $val;
+            }
+        }
+
+        return self::DEFAULT_MODE;
+    }
 }

src/Logs/Monolog/tests/Unit/HandlerTest.php

@@ -49,7 +49,7 @@ public function test_handle_record(): void
         $sharedState->method('getLogRecordLimits')->willReturn($limits);
         $handler = new Handler($this->provider, 100, true);
         $processor = function ($record) {
-            $record['extra'] = ['foo' => 'bar', 'baz' => 'bat'];
+            $record['extra'] = ['foo' => 'bar', 'baz' => ['bat']];
 
             return $record;
         };
@@ -68,16 +68,28 @@ function (LogRecord $logRecord) use ($scope, $sharedState) {
                     $this->assertGreaterThan(0, $readable->getTimestamp());
                     $this->assertSame('message', $readable->getBody());
                     $attributes = $readable->getAttributes();
-                    $this->assertCount(2, $attributes);
-                    $this->assertEquals(['context', 'extra'], array_keys($attributes->toArray()));
+                    $this->assertCount(8, $attributes);
+                    $this->assertEqualsCanonicalizing([
+                        'context',
+                        'context.foo',
+                        'extra',
+                        'extra.foo',
+                        'extra.baz',
+                        'exception.message',
+                        'exception.type',
+                        'exception.stacktrace',
+                    ], array_keys($attributes->toArray()));
+                    $this->assertSame('bar', $attributes->get('context')['foo']);
+                    $this->assertSame('bar', $attributes->get('context.foo'));
                     $this->assertEquals([
                         'foo' => 'bar',
-                        'baz' => 'bat',
+                        'baz' => ['bat'],
                     ], $attributes->get('extra'));
-                    $this->assertSame('bar', $attributes->get('context')['foo']);
-                    $this->assertSame('bar', $attributes->get('context')['foo']);
-                    $this->assertNotNull($attributes->get('context')['exception']);
-                    $this->assertNotNull($attributes->get('context')['exception']['message']);
+                    $this->assertSame('bar', $attributes->get('extra.foo'));
+                    $this->assertSame('["bat"]', $attributes->get('extra.baz'));
+                    $this->assertSame('kaboom', $attributes->get('exception.message'));
+                    $this->assertSame('Exception', $attributes->get('exception.type'));
+                    $this->assertNotNull($attributes->get('exception.stacktrace'));
 
                     return true;
                 }
@@ -86,4 +98,58 @@ function (LogRecord $logRecord) use ($scope, $sharedState) {
         /** @psalm-suppress UndefinedDocblockClass */
         $monolog->info('message', ['foo' => 'bar', 'exception' => new \Exception('kaboom', 500)]);
     }
+
+    public function test_handle_record_attrib_mode(): void
+    {
+        putenv(sprintf('%s=%s', Handler::OTEL_PHP_MONOLOG_ATTRIB_MODE, Handler::MODE_OTEL));
+
+        $channelName = 'test';
+        $scope = $this->createMock(InstrumentationScopeInterface::class);
+        $sharedState = $this->createMock(LoggerSharedState::class);
+        $resource = $this->createMock(ResourceInfo::class);
+        $limits = $this->createMock(LogRecordLimits::class);
+        $attributeFactory = Attributes::factory();
+        $limits->method('getAttributeFactory')->willReturn($attributeFactory);
+        $sharedState->method('getResource')->willReturn($resource);
+        $sharedState->method('getLogRecordLimits')->willReturn($limits);
+        $handler = new Handler($this->provider, 100, true);
+        $processor = function ($record) {
+            $record['extra'] = ['foo' => 'qux', 'bar' => 'quux'];
+
+            return $record;
+        };
+        $monolog = new \Monolog\Logger($channelName);
+        $monolog->pushHandler($handler);
+        $monolog->pushProcessor($processor);
+
+        $this->logger
+            ->expects($this->once())
+            ->method('emit')
+            ->with($this->callback(
+                function (LogRecord $logRecord) use ($scope, $sharedState) {
+                    $readable = new ReadableLogRecord($scope, $sharedState, $logRecord);
+                    $attributes = $readable->getAttributes();
+                    $this->assertCount(6, $attributes);
+                    $this->assertEqualsCanonicalizing([
+                        'foo',
+                        'bar',
+                        'baz',
+                        'exception.message',
+                        'exception.type',
+                        'exception.stacktrace',
+                    ], array_keys($attributes->toArray()));
+                    $this->assertSame('qux', $attributes->get('foo'));
+                    $this->assertSame('quux', $attributes->get('bar'));
+                    $this->assertSame('quuux', $attributes->get('baz'));
+                    $this->assertSame('kaboom', $attributes->get('exception.message'));
+                    $this->assertSame('Exception', $attributes->get('exception.type'));
+                    $this->assertNotNull($attributes->get('exception.stacktrace'));
+
+                    return true;
+                }
+            ));
+
+        /** @psalm-suppress UndefinedDocblockClass */
+        $monolog->info('message', ['baz' => 'quuux', 'exception' => new \Exception('kaboom', 500)]);
+    }
 }