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wip: capture spans for controllers automatically #282

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wip: capture spans for controllers automatically #282

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157 changes: 157 additions & 0 deletions src/Instrumentation/Symfony/src/SymfonyInstrumentation.php
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,10 @@
use OpenTelemetry\API\Trace\SpanKind;
use OpenTelemetry\API\Trace\StatusCode;
use OpenTelemetry\Context\Context;
use Symfony\Component\HttpKernel\KernelEvents;
use function OpenTelemetry\Instrumentation\hook;
use OpenTelemetry\SemConv\TraceAttributes;
use Symfony\Component\EventDispatcher\EventDispatcher;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\HttpKernel;
Expand Down Expand Up @@ -165,5 +167,160 @@ public static function register(): void
return $params;
},
);

/**
* Extract symfony event dispatcher known events and trace the controller
*
* Adapted from https://github.com/DataDog/dd-trace-php/blob/master/src/DDTrace/Integrations/Symfony/SymfonyIntegration.php
*/
hook(
EventDispatcher::class,
'dispatch',
pre: static function (
EventDispatcher $dispatcher,
array $params,
string $class,
string $function,
?string $filename,
?int $lineno,
) use ($instrumentation): array {
if (!isset($args[0])) {
return $params;
}

if (\is_object($args[0])) {
// dispatch($event, string $eventName = null)
$event = $args[0];
$eventName = isset($args[1]) && \is_string($args[1]) ? $args[1] : \get_class($event);
} elseif (\is_string($args[0])) {
// dispatch($eventName, Event $event = null)
$eventName = $args[0];
$event = isset($args[1]) && \is_object($args[1]) ? $args[1] : null;
} else {
return $params;
}

if ($eventName === 'kernel.controller' && \method_exists($event, 'getController')) {
$controller = $event->getController();
if (!($controller instanceof \Closure)) {
if (\is_callable($controller, false, $controllerName) && $controllerName !== null) {
if (\strpos($controllerName, '::') > 0) {
list($class, $method) = \explode('::', $controllerName);
if (isset($class, $method)) {
hook(
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Collaborator

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I don't think this will work with modern runtimes, where one long-lived application might handle many requests.
Maybe it should just manually create and end span on Symfony events?

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I think I'd rather memoize the hooks already in place. - this hook in particular is for the controller callable

$class,
$method,
pre: static function (
object $controller,
array $params,
string $class,
string $function,
?string $filename,
?int $lineno,
) use ($instrumentation) {
$parent = Context::getCurrent();
$builder = $instrumentation
->tracer()
->spanBuilder(sprintf('%s::%s', $class, $function))
->setParent($parent);
$span = $builder->startSpan();
$parent = Context::getCurrent();
Context::storage()->attach($span->storeInContext($parent));
},
post: static function (
object $controller,
array $params,
$result,
?\Throwable $exception
) {
$scope = Context::storage()->scope();
if (null === $scope) {
return;
}

$scope->detach();
$span = Span::fromContext($scope->context());

if (null !== $exception) {
$span->recordException($exception, [
TraceAttributes::EXCEPTION_ESCAPED => true,
]);
$span->setStatus(StatusCode::STATUS_ERROR, $exception->getMessage());
}

$span->end();
}
);
}
}
}
}
}

$parent = Context::getCurrent();
$span = $instrumentation->tracer()
->spanBuilder('symfony.' . $eventName)
->setParent($parent)
->startSpan();

Context::storage()->attach($span->storeInContext($parent));

if ($event === null) {
return $params;
}

self::setControllerNameAsSpanName($event, $eventName);

return $params;
},
post: static function (
EventDispatcher $dispatcher,
array $params,
$result,
?\Throwable $exception
) use ($instrumentation): void {
$scope = Context::storage()->scope();
if (null === $scope) {
return;
}

$scope->detach();
$span = Span::fromContext($scope->context());

if (null !== $exception) {
$span->recordException($exception, [
TraceAttributes::EXCEPTION_ESCAPED => true,
]);
$span->setStatus(StatusCode::STATUS_ERROR, $exception->getMessage());
}

$span->end();
}
);
}

private static function setControllerNameAsSpanName($event, $eventName): void
{
if (
!\defined("\Symfony\Component\HttpKernel\KernelEvents::CONTROLLER")
|| $eventName !== KernelEvents::CONTROLLER
|| !method_exists($event, 'getController')
) {
return;
}

/** @var callable $controllerAndAction */
$controllerAndAction = $event->getController();

if (
!is_array($controllerAndAction)
|| count($controllerAndAction) !== 2
|| !is_object($controllerAndAction[0])
) {
return;
}

$action = get_class($controllerAndAction[0]) . '::' . $controllerAndAction[1];
Span::getCurrent()->updateName($action);
}
}
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