aws2: fix retry header parsing (#1093)

The retry header was changed in [2.15.41]. Update the parsing
logic to work with the newer version.

[2.15.41]: https://github.com/aws/aws-sdk-java-v2/blob/8aaeeb0a001106db4f6add5bf9517dc130188b4b/.changes/2.15.41.json#L39

spectator-ext-aws2/src/main/java/com/netflix/spectator/aws2/SpectatorExecutionInterceptor.java

@@ -95,25 +95,34 @@ private void logRetryAttempt(ExecutionAttributes attrs) {
   /**
    * Extract the attempt number from the {@code amz-sdk-retry} header.
    */
-  private IpcAttempt extractAttempt(SdkHttpRequest request) {
+  private void updateAttempts(IpcLogEntry logEntry, SdkHttpRequest request) {
     int attempt = 0;
-    List<String> vs = request.headers().get("amz-sdk-retry");
+    int max = 0;
+    List<String> vs = request.headers().get("amz-sdk-request");
     if (vs != null) {
       for (String v : vs) {
-        // Format is: {requestCount - 1}/{lastBackoffDelay}/{availableRetryCapacity}
-        // See internal RetryHandler for more details.
-        int pos = v.indexOf('/');
+        // Format is: attempt={}; max={}
+        // https://github.com/aws/aws-sdk-java-v2/pull/2179/files
+        int pos = v.indexOf(';');
         if (pos > 0) {
-          try {
-            attempt = Integer.parseInt(v.substring(0, pos)) + 1;
-          } catch (NumberFormatException e) {
-            // If we cannot parse it, then attempt is unknown
-            attempt = 0;
-          }
+          attempt = parseFieldValue(v.substring(0, pos));
+          max = parseFieldValue(v.substring(pos + 1));
         }
       }
     }
-    return IpcAttempt.forAttemptNumber(attempt);
+    logEntry
+        .withAttempt(IpcAttempt.forAttemptNumber(attempt))
+        .withAttemptFinal(attempt == max);
+  }
+
+  private int parseFieldValue(String field) {
+    int pos = field.indexOf("=");
+    try {
+      return pos > 0 ? Integer.parseInt(field.substring(pos + 1)) : 0;
+    } catch (NumberFormatException e) {
+      // If we cannot parse it, then attempt is unknown
+      return 0;
+    }
   }
 
   @Override
@@ -131,9 +140,8 @@ public void beforeTransmission(Context.BeforeTransmission context, ExecutionAttr
         .withProtocol(IpcProtocol.http_1)
         .withHttpMethod(request.method().name())
         .withUri(request.getUri())
-        .withEndpoint(endpoint)
-        .withAttempt(extractAttempt(request))
-        .withAttemptFinal(false); // Don't know if it is the final attempt
+        .withEndpoint(endpoint);
+    updateAttempts(logEntry, request);
 
     request.headers().forEach((k, vs) -> vs.forEach(v -> logEntry.addRequestHeader(k, v)));
 

spectator-ext-aws2/src/test/java/com/netflix/spectator/aws2/SpectatorExecutionInterceptorTest.java

@@ -220,7 +220,7 @@ private void parseRetryHeaderTest(String expected, String header) {
     SdkHttpRequest request = SdkHttpRequest.builder()
         .method(SdkHttpMethod.POST)
         .uri(URI.create("https://ec2.us-east-1.amazonaws.com"))
-        .appendHeader("amz-sdk-retry", header)
+        .appendHeader("amz-sdk-request", header)
         .build();
     SdkHttpResponse response = SdkHttpResponse.builder()
         .statusCode(200)
@@ -238,27 +238,27 @@ private void parseRetryHeaderTest(String expected, String header) {
 
   @Test
   public void parseRetryHeaderInitial() {
-    parseRetryHeaderTest("initial", "0/NotUsed");
+    parseRetryHeaderTest("initial", "attempt=1; max=4");
   }
 
   @Test
   public void parseRetryHeaderSecond() {
-    parseRetryHeaderTest("second", "1/NotUsed");
+    parseRetryHeaderTest("second", "attempt=2; max=4");
   }
 
   @Test
   public void parseRetryHeaderThird() {
-    parseRetryHeaderTest("third_up", "2/NotUsed");
+    parseRetryHeaderTest("third_up", "attempt=3; max=4");
   }
 
   @Test
   public void parseRetryHeader50() {
-    parseRetryHeaderTest("third_up", "50/NotUsed");
+    parseRetryHeaderTest("third_up", "attempt=50; max=50");
   }
 
   @Test
   public void parseRetryHeaderInvalidNumber() {
-    parseRetryHeaderTest("unknown", "foo/bar");
+    parseRetryHeaderTest("unknown", "attempt=foo; max=bar");
   }
 
   @Test