fix: make ECS/IMDS credentials retry policies inherit from StandardRetryPolicy

Author: ianbotsf

.changes/28e51fe7-a4d8-4c99-a257-886ad89b7d02.json

@@ -0,0 +1,8 @@
+{
+    "id": "28e51fe7-a4d8-4c99-a257-886ad89b7d02",
+    "type": "bugfix",
+    "description": "improve retry policies for ECS and IMDS credentials to handle common network errors",
+    "issues": [
+        "awslabs/aws-sdk-kotlin#1626"
+    ]
+}

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

@@ -25,9 +25,6 @@ import aws.smithy.kotlin.runtime.io.closeIfCloseable
 import aws.smithy.kotlin.runtime.net.*
 import aws.smithy.kotlin.runtime.net.url.Url
 import aws.smithy.kotlin.runtime.operation.ExecutionContext
-import aws.smithy.kotlin.runtime.retries.policy.RetryDirective
-import aws.smithy.kotlin.runtime.retries.policy.RetryErrorType
-import aws.smithy.kotlin.runtime.retries.policy.RetryPolicy
 import aws.smithy.kotlin.runtime.serde.json.JsonDeserializer
 import aws.smithy.kotlin.runtime.telemetry.logging.logger
 import aws.smithy.kotlin.runtime.time.TimestampFormat
@@ -97,8 +94,6 @@ public class EcsCredentialsProvider(
             execution.endpointResolver = EndpointResolver { Endpoint(url) }
         }
 
-        op.execution.retryPolicy = EcsCredentialsRetryPolicy()
-
         logger.debug { "retrieving container credentials" }
         val client = SdkHttpClient(httpClient)
         val creds = try {
@@ -260,22 +255,6 @@ private class EcsCredentialsSerializer(
     }
 }
 
-internal class EcsCredentialsRetryPolicy : RetryPolicy<Any?> {
-    override fun evaluate(result: Result<Any?>): RetryDirective = when {
-        result.isSuccess -> RetryDirective.TerminateAndSucceed
-        else -> evaluate(result.exceptionOrNull()!!)
-    }
-
-    private fun evaluate(throwable: Throwable): RetryDirective = when (throwable) {
-        is CredentialsProviderException -> when {
-            throwable.sdkErrorMetadata.isThrottling -> RetryDirective.RetryError(RetryErrorType.Throttling)
-            throwable.sdkErrorMetadata.isRetryable -> RetryDirective.RetryError(RetryErrorType.ServerSide)
-            else -> RetryDirective.TerminateAndFail
-        }
-        else -> RetryDirective.TerminateAndFail
-    }
-}
-
 private val ecsV4Addr = IpV4Addr(169u, 254u, 170u, 2u)
 
 private val eksV4Addr = IpV4Addr(169u, 254u, 170u, 23u)

aws-runtime/aws-config/common/src/aws/sdk/kotlin/runtime/config/imds/ImdsRetryPolicy.kt

@@ -9,32 +9,25 @@ import aws.smithy.kotlin.runtime.http.HttpStatusCode
 import aws.smithy.kotlin.runtime.http.category
 import aws.smithy.kotlin.runtime.retries.policy.RetryDirective
 import aws.smithy.kotlin.runtime.retries.policy.RetryErrorType
-import aws.smithy.kotlin.runtime.retries.policy.RetryPolicy
+import aws.smithy.kotlin.runtime.retries.policy.StandardRetryPolicy
 import aws.smithy.kotlin.runtime.telemetry.logging.logger
 import kotlin.coroutines.CoroutineContext
 
-internal class ImdsRetryPolicy(
-    private val callContext: CoroutineContext,
-) : RetryPolicy<Any?> {
-    override fun evaluate(result: Result<Any?>): RetryDirective = when {
-        result.isSuccess -> RetryDirective.TerminateAndSucceed
-        else -> evaluate(result.exceptionOrNull()!!)
-    }
-
-    private fun evaluate(throwable: Throwable): RetryDirective = when (throwable) {
+internal class ImdsRetryPolicy(private val callContext: CoroutineContext) : StandardRetryPolicy() {
+    override fun evaluateSpecificExceptions(ex: Throwable) = when (ex) {
         is EC2MetadataError -> {
-            val status = throwable.status
+            val status = ex.status
             when {
                 status.category() == HttpStatusCode.Category.SERVER_ERROR -> RetryDirective.RetryError(RetryErrorType.ServerSide)
                 // 401 indicates the token has expired, this is retryable
                 status == HttpStatusCode.Unauthorized -> RetryDirective.RetryError(RetryErrorType.ServerSide)
                 else -> {
                     val logger = callContext.logger<ImdsRetryPolicy>()
-                    logger.debug { "Non retryable IMDS error: statusCode=$status; ${throwable.message}" }
-                    RetryDirective.TerminateAndFail
+                    logger.debug { "IMDS error: statusCode=$status; ${ex.message}" }
+                    null
                 }
             }
         }
-        else -> RetryDirective.TerminateAndFail
+        else -> null
     }
 }