libstore/s3: attach more information to error messages

In case of empty messages, it is good to print the raw error code.

Additionally, we print request IDs which can help users to reconcile
what happened with the service provider.

Change-Id: I4d83c011c1b7a5514e3d1b21123df38308279044
Signed-off-by: Raito Bezarius <raito@lix.systems>

lix/libstore/s3-binary-cache-store.cc

@@ -159,11 +159,24 @@ class RetryStrategy : public Aws::Client::DefaultRetryStrategy
     bool ShouldRetry(const Aws::Client::AWSError<Aws::Client::CoreErrors>& error, long attemptedRetries) const override
     {
         auto retry = Aws::Client::DefaultRetryStrategy::ShouldRetry(error, attemptedRetries);
-        if (retry)
-            printError("AWS error '%s' (%s), will retry in %d ms",
-                error.GetExceptionName(),
-                error.GetMessage(),
-                CalculateDelayBeforeNextRetry(error, attemptedRetries));
+        if (retry) {
+            if (error.GetExceptionName() != "") {
+                printError(
+                    "AWS error '%s' (%s) on request ID '%s', will retry in %d ms",
+                    error.GetExceptionName(),
+                    error.GetMessage(),
+                    error.GetRequestId(),
+                    CalculateDelayBeforeNextRetry(error, attemptedRetries)
+                );
+            } else {
+                printError(
+                    "AWS error (error type: %d) on request ID '%s', will retry in %d ms",
+                    error.GetErrorType(),
+                    error.GetRequestId(),
+                    CalculateDelayBeforeNextRetry(error, attemptedRetries)
+                );
+            }
+        }
         return retry;
     }
 };