feat: add ec2 region provider (#455)

Author: kneekey23

AWSClientRuntime/Sources/Regions/DefaultRegionResolver.swift

@@ -4,19 +4,25 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 //
+import AwsCommonRuntimeKit
 
 public struct DefaultRegionResolver: RegionResolver {
     public let providers: [RegionProvider]
 
-    public init(providers: [RegionProvider] = [EnvironmentRegionProvider(), ProfileRegionProvider()]) {
-        // TODO: add more region resolvers i.e. Imds, System Properties, etc
+    public init(providers: [RegionProvider] = [EnvironmentRegionProvider(), ProfileRegionProvider(), IMDSRegionProvider()]) {
+        // TODO: add more region resolvers i.e. System Properties, etc
         self.providers = providers
     }
 
     public func resolveRegion() -> String? {
         for provider in providers {
-            if let region = provider.resolveRegion() {
-                return region
+            do {
+                // TODO: Verify that this does not block calling thread. If it does, we need to solve this similar to the way we solve this for the credentials provider
+                if let region = try provider.resolveRegion().get() {
+                    return region
+                }
+            } catch {
+                return nil
             }
         }
         return nil

AWSClientRuntime/Sources/Regions/EnvironmentRegionProvider.swift

@@ -5,6 +5,7 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 import class Foundation.ProcessInfo
+import AwsCommonRuntimeKit
 
 public struct EnvironmentRegionProvider: RegionProvider {
     private let AWS_ENVIRON_REGION = "AWS_REGION"
@@ -14,8 +15,10 @@ public struct EnvironmentRegionProvider: RegionProvider {
         self.env = env
     }
 
-    public func resolveRegion() -> String? {
-        return env.environmentVariable(key: AWS_ENVIRON_REGION)
+    public func resolveRegion() -> Future<String?> {
+        let future = Future<String?>()
+        future.fulfill(env.environmentVariable(key: AWS_ENVIRON_REGION))
+        return future
     }
 }
 

AWSClientRuntime/Sources/Regions/IMDSRegionProvider.swift

@@ -0,0 +1,30 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+import AwsCommonRuntimeKit
+
+public struct IMDSRegionProvider: RegionProvider {
+    private let REGION_PATH = "/latest/meta-data/placement/region"
+    let imdsClient: IMDSClient
+    
+    public init() {
+        self.imdsClient = IMDSClient()
+    }
+    
+    public func resolveRegion() -> Future<String?> {
+        let future = Future<String?>()
+        
+        imdsClient.get(path: REGION_PATH, completion: { result in
+            switch result {
+            case .success(let region):
+                future.fulfill(region)
+            case .failure:
+                future.fulfill(nil)
+            }
+        })
+        return future
+    }
+}

AWSClientRuntime/Sources/Regions/ProfileRegionResolver.swift

@@ -5,14 +5,17 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 import AwsCommonRuntimeKit
+import ClientRuntime
 
 public struct ProfileRegionProvider: RegionProvider {
     let profileCollection: ProfileCollection
     let profileName: String
+    let logger: SwiftLogger
 
     init(profileCollection: ProfileCollection, profileName: String) {
         self.profileCollection = profileCollection
         self.profileName = profileName
+        self.logger = SwiftLogger(label: "ProfileRegionResolver")
     }
 
     //TODO: expose these config fields up to the sdk so customer can override path and profile name
@@ -22,10 +25,18 @@ public struct ProfileRegionProvider: RegionProvider {
         self.init(profileCollection: profileCollection, profileName: profileName)
     }
 
-    public func resolveRegion() -> String? {
+    public func resolveRegion() -> Future<String?> {
+        let future = Future<String?>()
         guard let profile = profileCollection.profile(for: profileName) else {
-            return nil
+            future.fulfill(nil)
+            return future
         }
-        return profile.getProperty(name: "region")
+        guard let region = profile.getProperty(name: "region") else {
+            logger.info("Attempting to use \(profileName), but no region was found")
+            future.fulfill(nil)
+            return future
+        }
+        future.fulfill(region)
+        return future
     }
 }

AWSClientRuntime/Sources/Regions/RegionProvider.swift

@@ -4,7 +4,8 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 //
+import AwsCommonRuntimeKit
 
 public protocol RegionProvider {
-    func resolveRegion() -> String?
+    func resolveRegion() -> Future<String?>
 }