Webhook: 503 error on fetching the signed events public key

[gopala000]

I'm using StrongGrid 0.98.0. I get 503 error on calling WebhookSettings.GetSignedEventsPublicKeyAsync() in production environment. But it works fine in test environment. On looking at the settings in SendGrid console both environments are setup exactly the same. Any thoughts on what could be the issue?

Exception while executing function: Functions.SendGridCallbackFunction Result: Failure
Exception: System.AggregateException: One or more errors occurred. (503: Service Unavailable)
 ---> StrongGrid.Utilities.SendGridException: 503: Service Unavailable
   at StrongGrid.Utilities.SendGridErrorHandler.OnResponse(IResponse response, Boolean httpErrorAsException)
   at Pathoschild.Http.Client.Internal.Request.Execute()
   at StrongGrid.Internal.AsObject[T](IRequest request, String propertyName, Boolean throwIfPropertyIsMissing, JsonSerializerOptions options)
   at SecureSave.Jobs.WebHooks.SendGridCallbackFunction.Run(HttpRequestData req, FunctionContext executionContext) in D:\a\1\s\SecureSave.Jobs\WebHooks\SendGridCallbackFunction.cs:line 51
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Microsoft.Azure.Functions.Worker.Invocation.DefaultFunctionInvoker`2.<>c.<InvokeAsync>b__6_0(Task`1 t) in D:\a\_work\1\s\src\DotNetWorker.Core\Invocation\DefaultFunctionInvoker.cs:line 32
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__273_0(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at Microsoft.Azure.Functions.Worker.Invocation.DefaultFunctionExecutor.ExecuteAsync(FunctionContext context) in D:\a\_work\1\s\src\DotNetWorker.Core\Invocation\DefaultFunctionExecutor.cs:line 45
   at Microsoft.Azure.Functions.Worker.OutputBindings.OutputBindingsMiddleware.Invoke(FunctionContext context, FunctionExecutionDelegate next) in D:\a\_work\1\s\src\DotNetWorker.Core\OutputBindings\OutputBindingsMiddleware.cs:line 16
   at Microsoft.Azure.Functions.Worker.Handlers.InvocationHandler.InvokeAsync(InvocationRequest request, WorkerOptions workerOptions) in D:\a\_work\1\s\src\DotNetWorker.Grpc\Handlers\InvocationHandler.cs:line 84
Stack:    at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Microsoft.Azure.Functions.Worker.Invocation.DefaultFunctionInvoker`2.<>c.<InvokeAsync>b__6_0(Task`1 t) in D:\a\_work\1\s\src\DotNetWorker.Core\Invocation\DefaultFunctionInvoker.cs:line 32
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__273_0(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at Microsoft.Azure.Functions.Worker.Invocation.DefaultFunctionExecutor.ExecuteAsync(FunctionContext context) in D:\a\_work\1\s\src\DotNetWorker.Core\Invocation\DefaultFunctionExecutor.cs:line 45
   at Microsoft.Azure.Functions.Worker.OutputBindings.OutputBindingsMiddleware.Invoke(FunctionContext context, FunctionExecutionDelegate next) in D:\a\_work\1\s\src\DotNetWorker.Core\OutputBindings\OutputBindingsMiddleware.cs:line 16
   at Microsoft.Azure.Functions.Worker.Handlers.InvocationHandler.InvokeAsync(InvocationRequest request, WorkerOptions workerOptions) in D:\a\_work\1\s\src\DotNetWorker.Grpc\Handlers\InvocationHandler.cs:line 84 

Code snippet:

            string logMessage = string.Empty;

            // Get your public key
            var strongGridClient = new StrongGrid.Client(_emailSettings.SendGridKey);
            var publicKey = await strongGridClient.WebhookSettings.GetSignedEventsPublicKeyAsync().ConfigureAwait(false);

            // Get the signature and the timestamp from the request headers
            // SIGNATURE_HEADER_NAME is a convenient constant provided so you don't have to remember the name of the header
            req.Headers.TryGetValues(WebhookParser.SIGNATURE_HEADER_NAME, out IEnumerable<string> signatures);
            var signature = signatures?.FirstOrDefault();

            // TIMESTAMP_HEADER_NAME is a convenient constant provided so you don't have to remember the name of the header
            req.Headers.TryGetValues(WebhookParser.TIMESTAMP_HEADER_NAME, out IEnumerable<string> timestamps);
            var timestamp = timestamps?.FirstOrDefault();

            // Parse the events. The signature will be automatically validated and a security exception thrown if unable to validate
            try
            {
                var parser = new WebhookParser();
                var events = await parser.ParseSignedEventsWebhookAsync(req.Body, publicKey, signature, timestamp).ConfigureAwait(false);

                // ... do something with the events...
                foreach(var e in events.OrderBy(r => r.Timestamp).ToArray())
                {
                    // My code

                }
            }

[Jericho]

HTTP errors in the 500 range indicate that the server can't complete the request because it encountered a problem. More specifically, 503 Service Unavailable error means that a website's server is not available right now. Most of the time, it occurs because the server is too busy or maintenance is being performed on it.

So, I encourage you to contact SendGrid directly to report this problem to them but keep us in the loop, let us know how they resolve it.

[Jericho]

@gopala000 I haven't heard back from you so I'm going to assume you were able to resolve the issue.

[gopala000]

My key was generated couple of years ago. SendGrid said permission may not be correctly set for webhook and asked to regenerate the key and try. I'll update if the issue persists. Thanks for your help!!