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fix: treat IO exceptions as retryable in HTTP engines #979

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merged 4 commits into from
Oct 19, 2023
Merged

fix: treat IO exceptions as retryable in HTTP engines #979

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2924a25
fix: treat IOExceptions as retryable in OkHttp engine
ianbotsf Oct 12, 2023
c2da47a
also make CRT IO exceptions retryable
ianbotsf Oct 18, 2023
4e77e0b
lint
ianbotsf Oct 18, 2023
8b57ec3
update changelog description
ianbotsf Oct 18, 2023
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5 changes: 5 additions & 0 deletions .changes/0645c929-bdfe-4d07-a131-b0b447422fff.json
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@@ -0,0 +1,5 @@
{
"id": "0645c929-bdfe-4d07-a131-b0b447422fff",
"type": "bugfix",
"description": "Treat all IO errors in OkHttp & CRT engines as retryable (e.g., socket errors, DNS lookup failures, etc.)"
}
30 changes: 28 additions & 2 deletions ...ttp-client-engine-crt/common/src/aws/smithy/kotlin/runtime/http/engine/crt/RequestUtil.kt
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Expand Up @@ -118,7 +118,11 @@ internal inline fun <T> mapCrtException(block: () -> T): T =
try {
block()
} catch (ex: CrtRuntimeException) {
throw HttpException(fmtCrtErrorMessage(ex.errorCode), errorCode = mapCrtErrorCode(ex.errorCode))
throw HttpException(
message = fmtCrtErrorMessage(ex.errorCode),
errorCode = mapCrtErrorCode(ex.errorName),
retryable = isRetryable(ex.errorName),
)
}

internal fun fmtCrtErrorMessage(errorCode: Int): String {
Expand All @@ -133,7 +137,7 @@ internal fun fmtCrtErrorMessage(errorCode: Int): String {
// See:
// IO Errors: https://github.com/awslabs/aws-c-io/blob/v0.13.19/include/aws/io/io.h#L89
// HTTP Errors: https://github.com/awslabs/aws-c-http/blob/v0.7.6/include/aws/http/http.h#L15
internal fun mapCrtErrorCode(code: Int): HttpErrorCode = when (CRT.errorName(code)) {
private fun mapCrtErrorCode(errorName: String?) = when (errorName) {
"AWS_IO_SOCKET_TIMEOUT" -> HttpErrorCode.SOCKET_TIMEOUT
"AWS_ERROR_HTTP_UNSUPPORTED_PROTOCOL" -> HttpErrorCode.PROTOCOL_NEGOTIATION_ERROR
"AWS_IO_SOCKET_NOT_CONNECTED" -> HttpErrorCode.CONNECT_TIMEOUT
Expand All @@ -143,6 +147,27 @@ internal fun mapCrtErrorCode(code: Int): HttpErrorCode = when (CRT.errorName(cod
else -> HttpErrorCode.SDK_UNKNOWN
}

internal fun mapCrtErrorCode(code: Int) = mapCrtErrorCode(CRT.errorName(code))

internal fun isRetryable(errorName: String?) = errorName?.let {
when {
// All IO errors are retryable
it.startsWith("AWS_IO_") || it.startsWith("AWS_ERROR_IO_") -> true

// Any connection closure is retryable
it in connectionClosedErrors -> true

// All proxy errors are retryable
it.startsWith("AWS_ERROR_HTTP_PROXY_") -> true

// Any connection manager issues are retryable
it.startsWith("AWS_ERROR_HTTP_CONNECTION_MANAGER_") -> true

// Any other errors are not retryable
else -> false
}
} ?: false // Unknown error codes are not retryable

private val tlsNegotiationErrors = setOf(
"AWS_IO_TLS_ERROR_NEGOTIATION_FAILURE",
"AWS_IO_TLS_ERROR_NOT_NEGOTIATED",
Expand All @@ -152,6 +177,7 @@ private val tlsNegotiationErrors = setOf(

private val connectionClosedErrors = setOf(
"AWS_ERROR_HTTP_CONNECTION_CLOSED",
"AWS_ERROR_HTTP_SERVER_CLOSED",
"AWS_IO_BROKEN_PIPE",
"AWS_IO_SOCKET_CLOSED",
)
46 changes: 46 additions & 0 deletions ...lient-engine-crt/common/test/aws/smithy/kotlin/runtime/http/engine/crt/RequestUtilTest.kt
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@@ -0,0 +1,46 @@
/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
package aws.smithy.kotlin.runtime.http.engine.crt

import kotlin.test.Test
import kotlin.test.assertFalse
import kotlin.test.assertTrue

class RequestUtilTest {
@Test
fun testExceptionRetryability() {
setOf(
// All IO errors are retryable
"AWS_IO_SOCKET_NETWORK_DOWN",
"AWS_ERROR_IO_OPERATION_CANCELLED",
"AWS_IO_DNS_NO_ADDRESS_FOR_HOST",

// Any connection closure is retryable
"AWS_ERROR_HTTP_CONNECTION_CLOSED",
"AWS_ERROR_HTTP_SERVER_CLOSED",
"AWS_IO_BROKEN_PIPE",

// All proxy errors are retryable
"AWS_ERROR_HTTP_PROXY_CONNECT_FAILED",
"AWS_ERROR_HTTP_PROXY_STRATEGY_NTLM_CHALLENGE_TOKEN_MISSING",
"AWS_ERROR_HTTP_PROXY_STRATEGY_TOKEN_RETRIEVAL_FAILURE",

// Any connection manager issues are retryable
"AWS_ERROR_HTTP_CONNECTION_MANAGER_INVALID_STATE_FOR_ACQUIRE",
"AWS_ERROR_HTTP_CONNECTION_MANAGER_VENDED_CONNECTION_UNDERFLOW",
"AWS_ERROR_HTTP_CONNECTION_MANAGER_SHUTTING_DOWN",
).forEach { name -> assertTrue(isRetryable(name), "Expected $name to be retryable!") }

setOf(
// Any other errors are not retryable
"AWS_ERROR_HTTP_INVALID_METHOD",
"AWS_ERROR_PKCS11_CKR_CANCEL",
"AWS_ERROR_PEM_MALFORMED",

// Unknown error codes are not retryable
null,
).forEach { name -> assertFalse(isRetryable(name), "Expected $name to not be retryable!") }
}
}
3 changes: 1 addition & 2 deletions ...-client-engine-okhttp/jvm/src/aws/smithy/kotlin/runtime/http/engine/okhttp/OkHttpUtils.kt
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Expand Up @@ -208,10 +208,9 @@ internal inline fun<T> mapOkHttpExceptions(block: () -> T): T =
try {
block()
} catch (ex: IOException) {
throw HttpException(ex, ex.errCode(), ex.isRetryable())
throw HttpException(ex, ex.errCode(), retryable = true) // All IOExceptions are retryable
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Question/Correctness: Is there any reason we wouldn't just make all IOExceptions retryable at the retry policy level?

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A few reasons came to mind:

  • IOException isn't in Kotlin stdlib—it's a JVM exception. Our retry policy is currently in common code. We could introduce an expect/actual function to dispatch down for platform-specific exceptions but it doesn't feel warranted for this use case.
  • IOException shouldn't be thrown by the CRT engine. If it is, then something is wrong that we likely don't understand and retrying may not be the best course of action.
  • Retry policies apply across the entirety of a request, not merely the HTTP call invocation. IOExceptions may occur during local IO errors such as streaming from a file, reading system properties, string encoding problems, etc. It seemed wise to scope these IOException retries to just the HTTP call itself.

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IOException isn't in Kotlin stdlib—it's a JVM exception. Our retry policy is currently in common code. We could introduce an expect/actual function to dispatch down for platform-specific exceptions but it doesn't feel warranted for this use case.

We already have an expect/actual for it FYI: https://github.com/awslabs/smithy-kotlin/blob/main/runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/io/Exceptions.kt#L8

IOException shouldn't be thrown by the CRT engine. If it is, then something is wrong that we likely don't understand and retrying may not be the best course of action.

It entirely depends on how we wrap the exceptions. To your point though CRT JVM bindings throw generic exceptions with a CRT specific error code IIRC. I wasn't thinking of CRT though I was thinking of other JVM specific bindings that customers may writer or that we may provide in the future. Doing it at the retry policy level would capture all of them.

Retry policies apply across the entirety of a request, not merely the HTTP call invocation. IOExceptions may occur during local IO errors such as streaming from a file, reading system properties, string encoding problems, etc. It seemed wise to scope these IOException retries to just the HTTP call itself.

I think we are wrapping all of our HTTP related exceptions into an HttpException with an error code if we can map it. I suppose because of this handling it at the specific engine level makes sense. We just have to remember to do it for each engine.

suggestion : If we are handling this at the specific engine level I think we ought to probably make the CRT exceptions retryable as well if we can in this PR. It would require looking at specific error codes probably.

}

private fun Exception.isRetryable(): Boolean = isCauseOrSuppressed<ConnectException>() || isConnectionClosedException()
private fun Exception.errCode(): HttpErrorCode = when {
isConnectTimeoutException() -> HttpErrorCode.CONNECT_TIMEOUT
isConnectionClosedException() -> HttpErrorCode.CONNECTION_CLOSED
Expand Down
12 changes: 6 additions & 6 deletions ...ngine-okhttp/jvm/test/aws/smithy/kotlin/runtime/http/engine/okhttp/OkHttpExceptionTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ package aws.smithy.kotlin.runtime.http.engine.okhttp

import aws.smithy.kotlin.runtime.http.HttpErrorCode
import aws.smithy.kotlin.runtime.http.HttpException
import org.junit.jupiter.api.Assertions.assertTrue
import java.io.EOFException
import java.io.IOException
import java.net.ConnectException
Expand All @@ -20,22 +21,21 @@ class OkHttpExceptionTest {
data class ExceptionTest(
val ex: Exception,
val expectedError: HttpErrorCode,
val expectedRetryable: Boolean = false,
)

@Test
fun testMapExceptions() {
val tests = listOf(
ExceptionTest(IOException("unknown"), expectedError = HttpErrorCode.SDK_UNKNOWN),
ExceptionTest(IOException(SocketTimeoutException("connect timeout")), expectedError = HttpErrorCode.CONNECT_TIMEOUT, true),
ExceptionTest(IOException().apply { addSuppressed(SocketTimeoutException("connect timeout")) }, expectedError = HttpErrorCode.CONNECT_TIMEOUT, true),
ExceptionTest(IOException(SocketTimeoutException("connect timeout")), expectedError = HttpErrorCode.CONNECT_TIMEOUT),
ExceptionTest(IOException().apply { addSuppressed(SocketTimeoutException("connect timeout")) }, expectedError = HttpErrorCode.CONNECT_TIMEOUT),
ExceptionTest(IOException(SocketTimeoutException("read timeout")), expectedError = HttpErrorCode.SOCKET_TIMEOUT),
ExceptionTest(IOException().apply { addSuppressed(SocketTimeoutException("read timeout")) }, expectedError = HttpErrorCode.SOCKET_TIMEOUT),
ExceptionTest(SocketTimeoutException("read timeout"), expectedError = HttpErrorCode.SOCKET_TIMEOUT),
ExceptionTest(IOException(SSLHandshakeException("negotiate error")), expectedError = HttpErrorCode.TLS_NEGOTIATION_ERROR),
ExceptionTest(ConnectException("test connect error"), expectedError = HttpErrorCode.SDK_UNKNOWN, true),
ExceptionTest(ConnectException("test connect error"), expectedError = HttpErrorCode.SDK_UNKNOWN),
// see https://github.com/awslabs/aws-sdk-kotlin/issues/905
ExceptionTest(IOException("unexpected end of stream on https://test.aws.com", EOFException("\\n not found: limit=0 content=...")), expectedError = HttpErrorCode.CONNECTION_CLOSED, expectedRetryable = true),
ExceptionTest(IOException("unexpected end of stream on https://test.aws.com", EOFException("\\n not found: limit=0 content=...")), expectedError = HttpErrorCode.CONNECTION_CLOSED),
)

for (test in tests) {
Expand All @@ -46,7 +46,7 @@ class OkHttpExceptionTest {
}

assertEquals(test.expectedError, ex.errorCode, "ex=$ex; ${ex.suppressedExceptions}; cause=${ex.cause}; causeSuppressed=${ex.cause?.suppressedExceptions}")
assertEquals(test.expectedRetryable, ex.sdkErrorMetadata.isRetryable)
assertTrue(ex.sdkErrorMetadata.isRetryable)
}
}
}
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