feat: make region optional (#970)

Author: ianbotsf

.changes/137f993a-88e6-4158-b55d-9ae0076d8501.json

@@ -0,0 +1,8 @@
+{
+    "id": "137f993a-88e6-4158-b55d-9ae0076d8501",
+    "type": "feature",
+    "description": "Make `region` an optional client config parameter to support multi-region use cases",
+    "issues": [
+        "awslabs/aws-sdk-kotlin#969"
+    ]
+}

aws-runtime/aws-config/common/src/aws/sdk/kotlin/runtime/auth/credentials/ProfileCredentialsProvider.kt

@@ -124,7 +124,7 @@ public class ProfileCredentialsProvider(
         }
     }
 
-    private suspend fun LeafProvider.toCredentialsProvider(region: LazyAsyncValue<String>): CredentialsProvider =
+    private suspend fun LeafProvider.toCredentialsProvider(region: LazyAsyncValue<String?>): CredentialsProvider =
         when (this) {
             is LeafProvider.NamedSource -> namedProviders[name]
                 ?: throw ProviderConfigurationException("unknown credentials source: $name")
@@ -164,7 +164,7 @@ public class ProfileCredentialsProvider(
 
     private suspend fun RoleArn.toCredentialsProvider(
         creds: Credentials,
-        region: LazyAsyncValue<String>,
+        region: LazyAsyncValue<String?>,
     ): CredentialsProvider = StsAssumeRoleCredentialsProvider(
         credentialsProvider = StaticCredentialsProvider(creds),
         roleArn = roleArn,

aws-runtime/aws-config/common/src/aws/sdk/kotlin/runtime/auth/credentials/StsWebIdentityCredentialsProvider.kt

@@ -43,7 +43,7 @@ private const val PROVIDER_NAME = "WebIdentityToken"
 public class StsWebIdentityCredentialsProvider(
     private val roleArn: String,
     private val webIdentityTokenFilePath: String,
-    private val region: String,
+    private val region: String?,
     private val roleSessionName: String? = null,
     private val duration: Duration = DEFAULT_CREDENTIALS_REFRESH_SECONDS.seconds,
     private val platformProvider: PlatformProvider = PlatformProvider.System,
@@ -67,7 +67,7 @@ public class StsWebIdentityCredentialsProvider(
         ): StsWebIdentityCredentialsProvider {
             val resolvedRoleArn = platformProvider.resolve(roleArn, AwsSdkSetting.AwsRoleArn, "roleArn")
             val resolvedTokenFilePath = platformProvider.resolve(webIdentityTokenFilePath, AwsSdkSetting.AwsWebIdentityTokenFile, "webIdentityTokenFilePath")
-            val resolvedRegion = platformProvider.resolve(region, AwsSdkSetting.AwsRegion, "region")
+            val resolvedRegion = region ?: AwsSdkSetting.AwsRegion.resolve(platformProvider)
             return StsWebIdentityCredentialsProvider(resolvedRoleArn, resolvedTokenFilePath, resolvedRegion, roleSessionName, duration, platformProvider, httpClient)
         }
     }

aws-runtime/aws-config/common/src/aws/sdk/kotlin/runtime/region/ResolveRegion.kt

@@ -5,7 +5,6 @@
 
 package aws.sdk.kotlin.runtime.region
 
-import aws.sdk.kotlin.runtime.ConfigurationException
 import aws.sdk.kotlin.runtime.InternalSdkApi
 import aws.sdk.kotlin.runtime.config.profile.AwsProfile
 import aws.sdk.kotlin.runtime.config.profile.loadAwsSharedConfig
@@ -15,14 +14,10 @@ import aws.smithy.kotlin.runtime.util.PlatformProvider
 import aws.smithy.kotlin.runtime.util.asyncLazy
 
 /**
- * Attempt to resolve the region to make requests to, throws [ConfigurationException] if region could not be
- * resolved.
+ * Attempt to resolve the AWS region to which requests should be made. Returns null if none was detected.
  */
 @InternalSdkApi
 public suspend fun resolveRegion(
     platformProvider: PlatformProvider = PlatformProvider.System,
     profile: LazyAsyncValue<AwsProfile> = asyncLazy { loadAwsSharedConfig(platformProvider).activeProfile },
-): String =
-    DefaultRegionProviderChain(platformProvider, profile = profile).use { providerChain ->
-        providerChain.getRegion() ?: throw ConfigurationException("unable to auto detect AWS region, tried: $providerChain")
-    }
+): String? = DefaultRegionProviderChain(platformProvider, profile = profile).use { it.getRegion() }

aws-runtime/aws-core/common/src/aws/sdk/kotlin/runtime/client/AwsSdkClientConfig.kt

@@ -17,7 +17,7 @@ public interface AwsSdkClientConfig : SdkClientConfig {
      * [global infrastructure](https://aws.amazon.com/about-aws/global-infrastructure/regions_az/) for more
      * information
      */
-    public val region: String
+    public val region: String?
 
     /**
      * Flag to toggle whether to use [FIPS](https://aws.amazon.com/compliance/fips/) endpoints when making requests.

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/AwsServiceConfigIntegration.kt

@@ -30,7 +30,6 @@ class AwsServiceConfigIntegration : KotlinIntegration {
                 [global infrastructure](https://aws.amazon.com/about-aws/global-infrastructure/regions_az/) for more
                 information
             """.trimIndent()
-            propertyType = ConfigPropertyType.Required()
             order = -100
         }
 

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/protocols/core/AwsHttpProtocolClientGenerator.kt

@@ -5,17 +5,19 @@
 
 package aws.sdk.kotlin.codegen.protocols.core
 
-import aws.sdk.kotlin.codegen.AwsRuntimeTypes
+import aws.sdk.kotlin.codegen.AwsRuntimeTypes.Core.Client.AwsClientOption
 import aws.sdk.kotlin.codegen.sdkId
+import software.amazon.smithy.codegen.core.Symbol
 import software.amazon.smithy.kotlin.codegen.core.*
-import software.amazon.smithy.kotlin.codegen.model.buildSymbol
+import software.amazon.smithy.kotlin.codegen.core.RuntimeTypes.Auth.Signing.AwsSigningCommon.AwsSigningAttributes
+import software.amazon.smithy.kotlin.codegen.core.RuntimeTypes.SmithyClient.SdkClientOption
 import software.amazon.smithy.kotlin.codegen.model.hasIdempotentTokenMember
 import software.amazon.smithy.kotlin.codegen.model.knowledge.AwsSignatureVersion4
-import software.amazon.smithy.kotlin.codegen.model.namespace
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.HttpBindingResolver
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.HttpProtocolClientGenerator
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.ProtocolGenerator
 import software.amazon.smithy.kotlin.codegen.rendering.protocol.ProtocolMiddleware
+import software.amazon.smithy.kotlin.codegen.utils.dq
 import software.amazon.smithy.model.knowledge.OperationIndex
 import software.amazon.smithy.model.knowledge.ServiceIndex
 import software.amazon.smithy.model.shapes.OperationShape
@@ -76,30 +78,38 @@ open class AwsHttpProtocolClientGenerator(
     private fun renderMergeServiceDefaults(writer: KotlinWriter) {
         // FIXME - we likely need a way to let customizations modify/override this
         // FIXME - we also need a way to tie in config properties added via integrations that need to influence the context
-        val putIfAbsentSym = buildSymbol { name = "putIfAbsent"; namespace(KotlinDependency.CORE, "util") }
-        val sdkClientOptionSym = buildSymbol { name = "SdkClientOption"; namespace(KotlinDependency.CORE, "client") }
-
         writer.dokka("merge the defaults configured for the service into the execution context before firing off a request")
         writer.withBlock(
             "private suspend fun mergeServiceDefaults(ctx: #T) {",
             "}",
             RuntimeTypes.Core.ExecutionContext,
         ) {
-            write("ctx.#T(#T.Region, config.region)", putIfAbsentSym, AwsRuntimeTypes.Core.Client.AwsClientOption)
-            write("ctx.#T(#T.ClientName, config.clientName)", putIfAbsentSym, sdkClientOptionSym)
-            write("ctx.#T(#T.LogMode, config.logMode)", putIfAbsentSym, sdkClientOptionSym)
+            putIfAbsent(AwsClientOption, "Region", nullable = true)
+            putIfAbsent(SdkClientOption, "ClientName")
+            putIfAbsent(SdkClientOption, "LogMode")
             // fill in auth/signing attributes
             if (AwsSignatureVersion4.isSupportedAuthentication(ctx.model, ctx.service)) {
                 // default signing context (most of this has been moved to auth schemes but some things like event streams still depend on this)
                 val signingServiceName = AwsSignatureVersion4.signingServiceName(ctx.service)
-                write("ctx.#T(#T.SigningService, #S)", putIfAbsentSym, RuntimeTypes.Auth.Signing.AwsSigningCommon.AwsSigningAttributes, signingServiceName)
-                write("ctx.#T(#T.SigningRegion, config.region)", putIfAbsentSym, RuntimeTypes.Auth.Signing.AwsSigningCommon.AwsSigningAttributes)
-                write("ctx.#T(#T.CredentialsProvider, config.credentialsProvider)", putIfAbsentSym, RuntimeTypes.Auth.Signing.AwsSigningCommon.AwsSigningAttributes)
+                putIfAbsent(AwsSigningAttributes, "SigningService", signingServiceName.dq())
+                putIfAbsent(AwsSigningAttributes, "SigningRegion", "config.region", nullable = true)
+                putIfAbsent(AwsSigningAttributes, "CredentialsProvider")
             }
 
             if (ctx.service.hasIdempotentTokenMember(ctx.model)) {
-                write("config.idempotencyTokenProvider?.let { ctx[#T.IdempotencyTokenProvider] = it }", sdkClientOptionSym)
+                putIfAbsent(SdkClientOption, "IdempotencyTokenProvider", nullable = true)
             }
         }
     }
 }
+
+private fun KotlinWriter.putIfAbsent(
+    attributesSymbol: Symbol,
+    name: String,
+    literalValue: String? = null,
+    nullable: Boolean = false,
+) {
+    val putSymbol = if (nullable) RuntimeTypes.Core.Utils.putIfAbsentNotNull else RuntimeTypes.Core.Utils.putIfAbsent
+    val actualValue = literalValue ?: "config.${name.replaceFirstChar(Char::lowercaseChar)}"
+    write("ctx.#T(#T.#L, #L)", putSymbol, attributesSymbol, name, actualValue)
+}

codegen/smithy-aws-kotlin-codegen/src/test/kotlin/aws/sdk/kotlin/codegen/AwsServiceConfigIntegrationTest.kt

@@ -45,7 +45,7 @@ class AwsServiceConfigIntegrationTest {
         val contents = writer.toString()
 
         val expectedProps = """
-    override val region: String = requireNotNull(builder.region) { "region is a required configuration property" }
+    override val region: String? = builder.region
     override val credentialsProvider: CredentialsProvider = builder.credentialsProvider ?: DefaultChainCredentialsProvider(httpClient = httpClient, region = region).manage()
 """
         contents.shouldContainOnlyOnceWithDiff(expectedProps)

services/s3/common/test/aws/sdk/kotlin/services/s3/CreateClientTest.kt

@@ -5,11 +5,9 @@
 
 package aws.sdk.kotlin.services.s3
 
-import io.kotest.matchers.string.shouldContain
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.runTest
 import kotlin.test.Test
-import kotlin.test.assertFailsWith
 
 /**
  * Validate the way service clients can be constructed.
@@ -18,12 +16,10 @@ import kotlin.test.assertFailsWith
  */
 @OptIn(ExperimentalCoroutinesApi::class)
 class CreateClientTest {
-
     @Test
     fun testMissingRegion() {
-        assertFailsWith<IllegalArgumentException> {
-            S3Client { }
-        }.message.shouldContain("region is a required configuration property")
+        // Should _not_ throw an exception since region is optional
+        S3Client { }
     }
 
     @Test

services/s3/e2eTest/src/S3TestUtils.kt

@@ -45,7 +45,7 @@ object S3TestUtils {
             client.createBucket {
                 bucket = testBucket
                 createBucketConfiguration {
-                    locationConstraint = BucketLocationConstraint.fromValue(client.config.region)
+                    locationConstraint = BucketLocationConstraint.fromValue(client.config.region!!)
                 }
             }