feat: imds client (#454)

Author: kneekey23

AWSClientRuntime/Sources/Auth/CredentialsProviderCRTAdapter.swift

@@ -18,7 +18,7 @@ struct CredentialsProviderCRTAdapter: CRTCredentialsProvider {
         self.allocator = defaultAllocator
     }
 
-    func getCredentials(credentialCallbackData: CRTCredentialsProviderCallbackData) {
+    func getCredentials(credentialCallbackData: CRTCredentialsCallbackData) {
         do {
             let credentialsResult = try credentialsProvider.getCredentials()
             let credentials = try credentialsResult.get()

AWSClientRuntime/Sources/IMDS/IMDSClient.swift

@@ -0,0 +1,34 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import AwsCommonRuntimeKit
+import ClientRuntime
+
+/// IMDSv2 Client
+///
+/// This client supports fetching tokens, retrying failures, and token caching according to the specified TTL.
+/// NOTE: This client ONLY supports IMDSv2. It will not fallback to IMDSv1.
+/// See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html#instance-metadata-transition-to-version-2 for more information.
+public class IMDSClient {
+    let crtIMDSClient: CRTIMDSClient
+    
+    public init(config: IMDSConfig = IMDSConfig()) {
+        let crtConfig = config.toCRTConfig()
+        self.crtIMDSClient = CRTIMDSClient(options: crtConfig)
+    }
+    
+    public func get(path: String, completion: @escaping (Result<String, ClientError>) -> Void) {
+        let callbackData = CRTIMDSClientResourceCallbackData { resource, error in
+            guard let resource = resource else {
+                completion(.failure(.crtError(error)))
+                return
+            }
+            completion(.success(resource))
+        }
+        crtIMDSClient.getResource(resourcePath: path, callbackData: callbackData)
+    }
+}

AWSClientRuntime/Sources/IMDS/IMDSConfig.swift

@@ -0,0 +1,25 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+import AwsCommonRuntimeKit
+import ClientRuntime
+
+//TODO: support more config options that are required to be supported when the CRT adds the ability to pass them down.
+public struct IMDSConfig {
+    let retries: Int
+    public init(retries: Int = 3) {
+        self.retries = retries
+    }
+}
+
+extension IMDSConfig {
+    // swiftlint:disable force_try
+    func toCRTConfig() -> CRTIMDSClientOptions {
+        let options = RetryOptions(backOffRetryOptions: ExponentialBackOffRetryOptions(maxRetries: retries))
+        let crtRetryer = try! CRTAWSRetryStrategy(options: options.toCRTType())
+        return CRTIMDSClientOptions(bootstrap: SDKDefaultIO.shared.clientBootstrap, retryStrategy: crtRetryer)
+    }
+}

AWSClientRuntime/Sources/Regions/ProfileRegionResolver.swift

@@ -29,4 +29,3 @@ public struct ProfileRegionProvider: RegionProvider {
         return profile.getProperty(name: "region")
     }
 }
-