/// <summary>
/// Attempts to deserialize the <see cref="LambdaInvocationEvent.Payload"/> into one of the expected trigger event objects.
/// </summary>
/// <param name="invocationEvent"></param>
/// <returns></returns>
private static (APIGatewayProxyRequest api, SQSEvent sqs) GetEventBody(LambdaInvocationEvent invocationEvent)
{
var api = JsonConvert.DeserializeObject <APIGatewayProxyRequest>(invocationEvent.Payload);
var sqs = JsonConvert.DeserializeObject <SQSEvent>(invocationEvent.Payload);
// The serializer will create the default object regardless of whether any of the fields deserialized.
// So if the object is missing a key field then set it to null to indicate the JSON was not for the event.
return((api?.Resource == null ? null : api),
(sqs?.Records == null ? null : sqs));
}
/// <summary>
/// Builds the <see cref="LambdaInvocationEvent"/> from a <see cref="InvocationUrls.NextInvocation"/> response.
/// </summary>
/// <param name="response"></param>
public static LambdaInvocationEvent Build(HttpResponseMessage response)
{
LambdaInvocationEvent evnt = new LambdaInvocationEvent();
var responseContentTask = response.Content.ReadAsStringAsync();
responseContentTask.Wait();
evnt.Payload = responseContentTask.Result;
evnt.AwsRequestId = GetHeaderValue(response.Headers, "Lambda-Runtime-Aws-Request-Id");
evnt.DeadlineTimestamp = GetHeaderValue(response.Headers, "Lambda-Runtime-Deadline-Ms");
evnt.InvokedFunctionArn = GetHeaderValue(response.Headers, "Lambda-Runtime-Invoked-Function-Arn");
evnt.TraceId = GetHeaderValue(response.Headers, "Lambda-Runtime-Aws-Trace-Id");
evnt.ClientContext = GetHeaderValue(response.Headers, "Lambda-Runtime-Aws-Client-Context");
evnt.CognitoIdentity = GetHeaderValue(response.Headers, "Lambda-Runtime-Aws-Cognito-Identity");
return(evnt);
}
/// <summary>
/// Retrieves the <see cref="LambdaInvocationEvent"/> associated with the currently executing Lambda.
/// </summary>
/// <param name="client"></param>
/// <param name="token"></param>
/// <returns></returns>
private static LambdaInvocationEvent GetInvocationEvent(CancellationToken token = default)
{
using (var client = new HttpClient())
using (var request = new HttpRequestMessage())
{
request.Method = new HttpMethod("GET");
request.Headers.Accept.Add(MediaTypeWithQualityHeaderValue.Parse("application/json"));
request.RequestUri = new Uri(NextInvocationUrl, UriKind.RelativeOrAbsolute);
var responseTask = client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, token);
responseTask.Wait();
var response = responseTask.Result;
if ((response.StatusCode != System.Net.HttpStatusCode.OK) &&
(response.StatusCode != System.Net.HttpStatusCode.NoContent))
{
throw new Exception($"API request '{request.RequestUri}' returned error status code {response.StatusCode}");
}
return(LambdaInvocationEvent.Build(response));
}
}
