I am stuck on how I should begin my lambda handler that will read some data from dynamodb. I have defined my api gateway model with the requests and response models, therefore do I need to state any status codes in the lambda handler ? Do I use API gateway proxy response event ? Any code examples
in Java would be helpful.
My notes on what I should include in the lambda handler:
access DB
map over table
Find attribute
Return response to api ?
What am I missing ? Thank you.
If you decided to use a non-proxy Lambda integration then you need to define an integration response using a regex. Here is an example using nodeJS:
lambda regex
Normally i declare my error messages just like this:
const errorMessages = {
INTERNAL_SERVER_ERROR: {
message: "Internal server error!",
code: 500
},
ERROR_BODY_INVALID: {
message: "Invalid request body",
code: 400
}
};
Then throw an error like this
exports.handler = function(event, context, callback) {
try {
// do something
} catch (error) {
callback(JSON.stringify(errorMessages.INTERNAL_SERVER_ERROR));
};
}
When a lambda error regex matches then it's mapped to the configured response status code.
P.D. If you are using Java this method does not work and you need to use proxy integration
Related
I have a rest API in aws api gateway that access's an external http endpoint and returns some data.
Every time this rest api is accessed and returns data, i need to trigger a lambda function that uses the data returned by the rest api. How can i achieve that ?
Tried looking for answers on this and all of them point to how to trigger a lambda function using a rest api.
You can do this in 2 ways.
When a request is sent to api gateway, invoke a lambda, inside this lambda access your external http endpoint and whatever the result comes, invoke another lambda.
something like this.
const invoke = async (funcName, payload) => {
const client = createClientForDefaultRegion(LambdaClient);
const command = new InvokeCommand({
FunctionName: funcName,
Payload: JSON.stringify(payload),
LogType: LogType.Tail,
});
const { Payload, LogResult } = await client.send(command);
const result = Buffer.from(Payload).toString();
const logs = Buffer.from(LogResult, "base64").toString();
return { logs, result };
};
Use stepfunctions with api gateway ( which would be similar to 1st operation)
I'm developing a chatbot on AWS Lex and I want to use Lambda function to branch my intent.
In order to do so, I created a Lambda as follows:
exports.handler = async (event) => {
console.log(event); //capture Lex params
/*
let { name, slots } = event.currentIntent
if(slots.MeetingType.toLowerCase() === 'on-line') {
return {
dialogAction: {
type: "ElicitSlot",
intentName: name,
slotToElicit: "InvitationLink",
slots
}
}
}
return {
dialogAction: {
type: "Delegate",
slots
}
}
*/
};
But as you can see, even when the function does nothing but log Lex output, I'm getting this error message in Lex:
An error has occurred: The server encountered an error processing the
Lambda response
Any help would be appreciated.
Because you are trying to build a Lex chatbot using JavaScript, please refer to this use case in the AWS SDK for JavaScript DEV Guide. It will walk you through this use case:
Building an Amazon Lex chatbot
Once you get this working, you can port the logic to a Lambda function.
Amazon Lex is giving you this error message because the Lambda function has failed during execution.
Enable CloudWatch logging for your Lambda function and check the logs after Lex has called it. The logs should provide you with more specific details about what's caused the code to break/fail. From there you should have a better idea of how to resolve the issue.
Feel free to post the output from the logs if you need more assistance with debugging the issue.
I'm trying to get my IoT device to fire off a Lambda function. Been trying for a few hours to no avail.
My lambda function is simple:
exports.handler = async (event) => {
// TODO implement
const response = {
statusCode: 200,
body: JSON.stringify(event.message),
};
return response;
};
I've setup my IoT rule to trigger the lambda function with SELECT * FROM 'iot/trigger-lambda'. When I publish a message to the iot/trigger-lambda topic from AWS IoT's Test functionality, the lambda function triggers successfully. But, when I publish my message from my device, I get the following error:
{
"ruleName": "ruleTriggerLambda",
"topic": "iot/trigger-lambda",
"cloudwatchTraceId": "xxx-yyy-zzz",
"clientId": "ABC123",
"base64OriginalPayload": "eydvcGVyYGTpb24nOiAncHV0T2JqZWN0JywgJ2J1Y2tldCc6ICdyZWR3YXZlLWFwcC1kZXYnLCAna2V5JzogJ3JlYWNoYmFjay56aXAnLQWncmVwbHlUbyc6ICdpb3QvdGhyGHT0aWQtMDAwMS9wcmUtc2lnbmVkLBNzLXVybC1yBBNwb25zZXMnfSBbMV0=",
"failures": [
{
"failedAction": "LambdaAction",
"failedResource": "arn:aws:lambda:us-east-1:xxx:function:lambdaTriggerLambda",
"errorMessage": "Failed to invoke lambda function. Received Server error from Lambda. The error code is 400"
}
]
}
When I added the lambda function to my rule, AWS indicated it would create the correction permissions. I've also tried updating the permissions of the lambda function.
Any suggestions on how to fix this? Any help/information is much appreciated.
Edit: after 4 hours or ripping my hair out
It turned out to be the format of the data that I was sending as a payload from my IoT device. Let me explain, if someone can tell me why this is, I'd love to know.
I was using my mac as my device and I implemented this code from the AWS IoT Python SDK. My message looked like this:
message = {"message": "test message"}
It seems like pretty straight forward json.
The code that is publishing the message looks like this:
mqtt_connection.publish(
topic=args.topic,
payload=args.message,
qos=mqtt.QoS.AT_LEAST_ONCE)
The payload being received at AWS IoT Core looked like this:
{'message': 'test message'} [1]
And was accompanied by an error message like so: We cannot display the message as JSON, and are instead displaying it as UTF-8 String.
I guess I'm a little dense for not connecting the dots but it turns out I had to do the following to my code:
mqtt_connection.publish(
topic=args.topic,
payload=json.dumps(args.message).replace("\"", '').replace("[1]", '').replace("'", '"'),
qos=mqtt.QoS.AT_LEAST_ONCE)
Hopefully this explanation will help someone in the future.
I am unable to map error from lambda to Status Code 400.
My lambda code in Go is as follows
package main
import (
"errors"
"github.com/aws/aws-lambda-go/lambda"
)
func main() {
lambda.Start(returnError)
}
func returnError() error {
return errors.New("Something went wrong!")
}
I have added Response Integration to Status Code 400 as follows.
Still I get response Status Code 200 as follows. I want it to be 400
I am already using mapping template for request and response. I want to separate Lambda from mapping & validation.
You need to setup Lambda as Proxy integration and then write to return status code from lambda as 400.
Here is an existing post:
Is there a way to change the http status codes returned by Amazon API Gateway?
I have a multi-endpoint webservice written in Flask and running on API Gateway and Lambda thanks to Zappa.
I have a second, very tiny, lambda, written in Node, that periodically hits one of the webservice endpoints. I do this by configuring the little lambda to have Internet access then use Node's https.request with these options:
const options = {
hostname: 'XXXXXXXXXX.execute-api.us-east-1.amazonaws.com',
port: 443,
path: '/path/to/my/endpoint',
method: 'POST',
headers: {
'Authorization': `Bearer ${s3cretN0tSt0r3d1nTheC0de}`,
}
};
and this works beautifully. But now I am wondering whether I should instead make the little lambda invoke the API endpoint directly using the AWS SDK. I have seen other S.O. questions on invoking lambdas from lambdas but I did not see any examples where the target lambda was a multi-endpoint webservice. All the examples I found used new AWS.Lambda({...}) and then called invokeFunction with params.
Is there a way to pass, say, an event to the target lambda which contained the path of the specific endpoint I want to call? (and the auth headers, etc.) * * * * OR * * * * is this just a really dumb idea, given that I have working code already? My thinking is that a direct SDK lambda invocation might (is this true?) bypass API Gateway and be cheaper, BUT, hitting the endpoint directly via API Gateway is better for logging. And since the periodic lambda runs once a day, it's probably free anyway.
If what I have now is best, that's a fine answer. A lambda invocation answer would be cool too, since I've not been able to find a good example in which the target lambda had multiple https endpoints.
You can invoke the Lambda function directly using the invoke method in AWS SDK.
var params = {
ClientContext: "MyApp",
FunctionName: "MyFunction",
InvocationType: "Event",
LogType: "Tail",
Payload: <Binary String>,
Qualifier: "1"
};
lambda.invoke(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
/*
data = {
FunctionError: "",
LogResult: "",
Payload: <Binary String>,
StatusCode: 123
}
*/
});
Refer the AWS JavaScript SDK lambda.invoke method for more details.