Dart / Flutter

CloudMock does not require a custom Dart SDK. Configure the AWS SDK for Dart or your HTTP client to point at the CloudMock gateway. This works for Flutter mobile apps, Flutter web, and server-side Dart.

AWS SDK for Dart (aws_common / smithy)

The official AWS SDK for Dart is still in developer preview. For services that have a published Dart package, configure the endpoint:

pubspec.yaml

dependencies:
  aws_s3_api: ^0.2.0        # if available
  aws_dynamodb_api: ^0.2.0   # if available
  aws_common: ^0.7.0

Endpoint configuration

import 'package:aws_s3_api/s3-2006-03-01.dart';
import 'package:aws_common/aws_common.dart';

final credentials = AWSCredentialsProvider(AWSCredentials(
  'test',  // accessKeyId
  'test',  // secretAccessKey
));

final s3 = S3(
  region: 'us-east-1',
  credentialsProvider: credentials,
  endpointUrl: Uri.parse('http://localhost:4566'),
);

Using the http package directly

If the official AWS Dart SDK does not cover the service you need, you can call CloudMock’s REST API directly using Dart’s http package or dio:

http package

import 'package:http/http.dart' as http;
import 'dart:convert';

const cloudmockUrl = 'http://localhost:4566';

// Create an S3 bucket
Future<void> createBucket(String name) async {
  final response = await http.put(
    Uri.parse('$cloudmockUrl/$name'),
    headers: {
      'Authorization': 'AWS4-HMAC-SHA256 ...',
      'x-amz-content-sha256': 'UNSIGNED-PAYLOAD',
    },
  );
  print('Create bucket: ${response.statusCode}');
}

// List S3 buckets
Future<void> listBuckets() async {
  final response = await http.get(
    Uri.parse(cloudmockUrl),
    headers: {
      'Authorization': 'AWS4-HMAC-SHA256 ...',
    },
  );
  print('Buckets: ${response.body}');
}

dio

import 'package:dio/dio.dart';

final dio = Dio(BaseOptions(
  baseUrl: 'http://localhost:4566',
  headers: {
    'Authorization': 'AWS4-HMAC-SHA256 ...',
  },
));

// DynamoDB - CreateTable
Future<void> createTable() async {
  final response = await dio.post(
    '/',
    data: {
      'TableName': 'Users',
      'KeySchema': [
        {'AttributeName': 'UserId', 'KeyType': 'HASH'}
      ],
      'AttributeDefinitions': [
        {'AttributeName': 'UserId', 'AttributeType': 'S'}
      ],
      'BillingMode': 'PAY_PER_REQUEST',
    },
    options: Options(headers: {
      'X-Amz-Target': 'DynamoDB_20120810.CreateTable',
      'Content-Type': 'application/x-amz-json-1.0',
    }),
  );
  print('Table created: ${response.data}');
}

Community packages

Several community packages provide higher-level AWS clients for Dart:

• aws_s3_api — S3 operations with Dart types
• aws_dynamodb_api — DynamoDB operations
• aws_cognito_identity_provider — Cognito User Pools

Most accept an endpointUrl parameter. Set it to http://localhost:4566 (or the appropriate host for your environment).

Flutter networking

Android emulator

The Android emulator cannot reach localhost on the host machine. Use 10.0.2.2 instead:

const cloudmockUrl = 'http://10.0.2.2:4566';

iOS Simulator

The iOS Simulator shares the host Mac’s network stack. localhost works directly:

const cloudmockUrl = 'http://localhost:4566';

Platform-aware endpoint

import 'dart:io' show Platform;

String get cloudmockUrl {
  if (Platform.isAndroid) {
    return 'http://10.0.2.2:4566';
  }
  return 'http://localhost:4566';
}

Flutter Web

When running flutter run -d chrome, the app runs in the browser on the same machine as CloudMock. Use http://localhost:4566. CORS headers are returned by CloudMock by default.

Cleartext traffic (Android)

Android blocks cleartext HTTP by default. Add to android/app/src/main/AndroidManifest.xml:

<application
    android:usesCleartextTraffic="true"
    ... >

Or use a more targeted network security config as described in the Kotlin guide.

App Transport Security (iOS)

Add to ios/Runner/Info.plist:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsLocalNetworking</key>
    <true/>
</dict>

Signing requests

AWS APIs require Signature V4 signed requests. If you are calling CloudMock directly (without an AWS SDK), you have two options:

1. Set IAM mode to none in CloudMock configuration, which bypasses all authentication:

   iam:
     mode: none

   Then you can make unsigned requests. This is the simplest approach for development.

2. Use an AWS SigV4 signing library for Dart. The aws_common package provides signing utilities.

When using an official AWS SDK package with endpointUrl, signing is handled automatically.

Common issues

AWS SDK maturity

The official AWS SDK for Dart is in developer preview. Not all services have published packages. For services without a Dart SDK, use direct HTTP calls with the X-Amz-Target header for JSON-protocol services or REST-style URLs for REST-XML services.

Emulator IP addresses

Use 10.0.2.2 for Android Emulator and localhost for iOS Simulator. Physical devices require the host machine’s IP on the local network.