Feat: Failed requests HTTP client

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 * Feat: Enrich events with more context (#452)
 * Feat: Add Culture Context (#491)
+* Feat: Capture failed requests as event (#473)
 * Feat: `beforeSend` callback accepts async code (#494)
 
 ## Breaking Changes:

dart/lib/src/http_client/breadcrumb_client.dart

@@ -0,0 +1,94 @@
+import 'package:http/http.dart';
+import '../protocol.dart';
+import '../hub.dart';
+import '../hub_adapter.dart';
+
+/// A [http](https://pub.dev/packages/http)-package compatible HTTP client
+/// which records requests as breadcrumbs.
+///
+/// Remarks:
+/// If this client is used as a wrapper, a call to close also closes the
+/// given client.
+///
+/// The `BreadcrumbClient` can be used as a standalone client like this:
+/// ```dart
+/// import 'package:sentry/sentry.dart';
+///
+/// var client = BreadcrumbClient();
+/// try {
+///  var uriResponse = await client.post('https://example.com/whatsit/create',
+///      body: {'name': 'doodle', 'color': 'blue'});
+///  print(await client.get(uriResponse.bodyFields['uri']));
+/// } finally {
+///  client.close();
+/// }
+/// ```
+///
+/// The `BreadcrumbClient` can also be used as a wrapper for your own
+/// HTTP [Client](https://pub.dev/documentation/http/latest/http/Client-class.html):
+/// ```dart
+/// import 'package:sentry/sentry.dart';
+/// import 'package:http/http.dart' as http;
+///
+/// final myClient = http.Client();
+///
+/// var client = BreadcrumbClient(client: myClient);
+/// try {
+///  var uriResponse = await client.post('https://example.com/whatsit/create',
+///      body: {'name': 'doodle', 'color': 'blue'});
+///  print(await client.get(uriResponse.bodyFields['uri']));
+/// } finally {
+///  client.close();
+/// }
+/// ```
+class BreadcrumbClient extends BaseClient {
+  BreadcrumbClient({Client? client, Hub? hub})
+      : _hub = hub ?? HubAdapter(),
+        _client = client ?? Client();
+
+  final Client _client;
+  final Hub _hub;
+
+  @override
+  Future<StreamedResponse> send(BaseRequest request) async {
+    // See https://develop.sentry.dev/sdk/event-payloads/breadcrumbs/
+
+    var requestHadException = false;
+    int? statusCode;
+    String? reason;
+
+    final stopwatch = Stopwatch();
+    stopwatch.start();
+
+    try {
+      final response = await _client.send(request);
+
+      statusCode = response.statusCode;
+      reason = response.reasonPhrase;
+
+      return response;
+    } catch (_) {
+      requestHadException = true;
+      rethrow;
+    } finally {
+      stopwatch.stop();
+
+      var breadcrumb = Breadcrumb.http(
+        level: requestHadException ? SentryLevel.error : SentryLevel.info,
+        url: request.url,
+        method: request.method,
+        statusCode: statusCode,
+        reason: reason,
+        requestDuration: stopwatch.elapsed,
+      );
+
+      _hub.addBreadcrumb(breadcrumb);
+    }
+  }
+
+  @override
+  void close() {
+    // See https://github.com/getsentry/sentry-dart/pull/226#discussion_r536984785
+    _client.close();
+  }
+}

dart/lib/src/http_client/failed_request_client.dart

@@ -0,0 +1,241 @@
+import 'package:http/http.dart';
+import '../protocol.dart';
+import '../hub.dart';
+import '../hub_adapter.dart';
+import '../throwable_mechanism.dart';
+import 'sentry_http_client.dart';
+
+/// A [http](https://pub.dev/packages/http)-package compatible HTTP client
+/// which records events for failed requests.
+///
+/// Configured with default values, this captures requests which throw an
+/// exception.
+/// This can be for example for the following reasons:
+/// - In an browser environment this can be requests which fail because of CORS.
+/// - In an mobile or desktop application this can be requests which failed
+///   because the connection was interrupted.
+///
+/// Additionally you can configure specific HTTP response codes to be considered
+/// as a failed request. In the following example, the status codes 404 and 500
+/// are considered a failed request.
+///
+/// ```dart
+/// import 'package:sentry/sentry.dart';
+///
+/// var client = FailedRequestClient(
+///   failedRequestStatusCodes: [SentryStatusCode.range(400, 404), SentryStatusCode(500)]
+/// );
+/// ```
+///
+/// Remarks:
+/// If this client is used as a wrapper, a call to close also closes the
+/// given client.
+///
+/// The `FailedRequestClient` can be used as a standalone client like this:
+/// ```dart
+/// import 'package:sentry/sentry.dart';
+///
+/// var client = FailedRequestClient();
+/// try {
+///  var uriResponse = await client.post('https://example.com/whatsit/create',
+///      body: {'name': 'doodle', 'color': 'blue'});
+///  print(await client.get(uriResponse.bodyFields['uri']));
+/// } finally {
+///  client.close();
+/// }
+/// ```
+///
+/// The `FailedRequestClient` can also be used as a wrapper for your own
+/// HTTP [Client](https://pub.dev/documentation/http/latest/http/Client-class.html):
+/// ```dart
+/// import 'package:sentry/sentry.dart';
+/// import 'package:http/http.dart' as http;
+///
+/// final myClient = http.Client();
+///
+/// var client = FailedRequestClient(client: myClient);
+/// try {
+///  var uriResponse = await client.post('https://example.com/whatsit/create',
+///      body: {'name': 'doodle', 'color': 'blue'});
+///  print(await client.get(uriResponse.bodyFields['uri']));
+/// } finally {
+///  client.close();
+/// }
+/// ```
+class FailedRequestClient extends BaseClient {
+  FailedRequestClient({
+    this.maxRequestBodySize = MaxRequestBodySize.small,
+    this.failedRequestStatusCodes = const [],
+    this.captureFailedRequests = true,
+    this.sendDefaultPii = false,
+    Client? client,
+    Hub? hub,
+  })  : _hub = hub ?? HubAdapter(),
+        _client = client ?? Client();
+
+  final Client _client;
+  final Hub _hub;
+
+  /// Configures wether to record exceptions for failed requests.
+  /// Examples for captures exceptions are:
+  /// - In an browser environment this can be requests which fail because of CORS.
+  /// - In an mobile or desktop application this can be requests which failed
+  ///   because the connection was interrupted.
+  final bool captureFailedRequests;
+
+  /// Configures up to which size request bodies should be included in events.
+  /// This does not change wether an event is captured.
+  final MaxRequestBodySize maxRequestBodySize;
+
+  /// Describes which HTTP status codes should be considered as a failed
+  /// requests.
+  ///
+  /// Per default no status code is considered a failed request.
+  final List<SentryStatusCode> failedRequestStatusCodes;
+
+  final bool sendDefaultPii;
+
+  @override
+  Future<StreamedResponse> send(BaseRequest request) async {
+    int? statusCode;
+    Object? exception;
+    StackTrace? stackTrace;
+
+    final stopwatch = Stopwatch();
+    stopwatch.start();
+
+    try {
+      final response = await _client.send(request);
+      statusCode = response.statusCode;
+      return response;
+    } catch (e, st) {
+      exception = e;
+      stackTrace = st;
+      rethrow;
+    } finally {
+      stopwatch.stop();
+
+      // If captureFailedRequests is true, there statusCode is null.
+      // So just one of these blocks can be called.
+
+      if (captureFailedRequests && exception != null) {
+        await _captureEvent(
+          exception: exception,
+          stackTrace: stackTrace,
+          request: request,
+          requestDuration: stopwatch.elapsed,
+        );
+      } else if (failedRequestStatusCodes.containsStatusCode(statusCode)) {
+        // Capture an exception if the status code is considered bad
+        await _captureEvent(
+          request: request,
+          reason: failedRequestStatusCodes.toDescription(),
+          requestDuration: stopwatch.elapsed,
+        );
+      }
+    }
+  }
+
+  @override
+  void close() {
+    // See https://github.com/getsentry/sentry-dart/pull/226#discussion_r536984785
+    _client.close();
+  }
+
+  // See https://develop.sentry.dev/sdk/event-payloads/request/
+  Future<void> _captureEvent({
+    Object? exception,
+    StackTrace? stackTrace,
+    String? reason,
+    required Duration requestDuration,
+    required BaseRequest request,
+  }) {
+    // As far as I can tell there's no way to get the uri without the query part
+    // so we replace it with an empty string.
+    final urlWithoutQuery = request.url.replace(query: '').toString();
+
+    final query = request.url.query.isEmpty ? null : request.url.query;
+
+    final sentryRequest = SentryRequest(
+      method: request.method,
+      headers: sendDefaultPii ? request.headers : null,
+      url: urlWithoutQuery,
+      queryString: query,
+      cookies: sendDefaultPii ? request.headers['Cookie'] : null,
+      data: _getDataFromRequest(request),
+      other: {
+        'content_length': request.contentLength.toString(),
+        'duration': requestDuration.toString(),
+      },
+    );
+
+    final mechanism = Mechanism(
+      type: 'SentryHttpClient',
+      description: reason,
+    );
+    final throwableMechanism = ThrowableMechanism(mechanism, exception);
+
+    final event = SentryEvent(
+      throwable: throwableMechanism,
+      request: sentryRequest,
+    );
+    return _hub.captureEvent(event, stackTrace: stackTrace);
+  }
+
+  // Types of Request can be found here:
+  // https://pub.dev/documentation/http/latest/http/http-library.html
+  Object? _getDataFromRequest(BaseRequest request) {
+    final contentLength = request.contentLength;
+    if (contentLength == null) {
+      return null;
+    }
+    if (!maxRequestBodySize.shouldAddBody(contentLength)) {
+      return null;
+    }
+    if (request is MultipartRequest) {
+      final data = <String, String>{...request.fields};
+      return data;
+    }
+
+    if (request is Request) {
+      return request.body;
+    }
+
+    // There's nothing we can do for a StreamedRequest
+    return null;
+  }
+}
+
+extension _ListX on List<SentryStatusCode> {
+  bool containsStatusCode(int? statusCode) {
+    if (statusCode == null) {
+      return false;
+    }
+    return any((element) => element.isInRange(statusCode));
+  }
+
+  String toDescription() {
+    final ranges = join(', ');
+    return 'This event was captured because the '
+        'request status code was in [$ranges]';
+  }
+}
+
+extension _MaxRequestBodySizeX on MaxRequestBodySize {
+  bool shouldAddBody(int contentLength) {
+    if (this == MaxRequestBodySize.never) {
+      return false;
+    }
+    if (this == MaxRequestBodySize.always) {
+      return true;
+    }
+    if (this == MaxRequestBodySize.medium && contentLength <= 10000) {
+      return true;
+    }
+
+    if (this == MaxRequestBodySize.small && contentLength <= 4000) {
+      return true;
+    }
+    return false;
+  }
+}