AWS - Display all connected users in DynamoDB [closed] - amazon-web-services

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This is WEBSOCKET API. I am very new to this.
So I have this command in CLI which connects to the api gateway and store the username(Zeus) in dynamodb
wscat -c [wssURL]?username=Zeus
It should return the username/s in CLI that is/are connected to the API Gateway. This is my lambda that is connected to a route in my API Gateway.
exports.handler = async function(event, context, callback) {
// let sender = JSON.parse(event.body).sender;
let scannedItems = await displayUsers();
console.log(scannedItems);
callback(null, {
statusCode: 200
});
return {};
};
async function displayUsers() {
return ddb.scan(
{
TableName: 'Chat',
ProjectionExpression: "username"
}).promise();
}
How can I return my scannedItems in the CLI?

Your handler is not returning the scannedItems variable, just logging it in CloudWatch.

Related

Lex: The server encountered an error processing lambda

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.

GCP cloud build VIEW RAW logs link

I have written a small cloud function in GCP which is subscribed to Pub/Sub event. When any cloud builds triggered function post message into the slack channel over webook.
In response, we get lots of details to trigger name, branch name, variables details but i am more interested in Build logs URL.
Currently getting build logs URL in response is like : logUrl: https://console.cloud.google.com/cloud-build/builds/899-08sdf-4412b-e3-bd52872?project=125205252525252
which requires GCP console access to check logs.
While in the console there an option View Raw. Is it possible to get that direct URL in the event response? so that i can directly sent it to slack and anyone can access direct logs without having GCP console access.
In your Cloud Build event message, you need to extract 2 values from the JSON message:
logsBucket
id
The raw file is stored here
<logsBucket>/log-<id>.txt
So, you can get it easily in your function with Cloud Storage client library (preferred solution) or with a simple HTTP Get call to the storage API.
If you need more guidance, let me know your dev language, I will send you a piece of code.
as #guillaume blaquiere helped.
Just sharing the piece of code used in cloud function to generate the singedURL of cloud build logs.
var filename ='log-' + build.id + '.txt';
var file = gcs.bucket(BUCKET_NAME).file(filename);
const getURL = async () => {
return new Promise((resolve, reject) => {
file.getSignedUrl({
action: 'read',
expires: Date.now() + 76000000
}, (err, url) => {
if (err) {
console.error(err);
reject(err);
}
console.log("URL");
resolve(url);
});
})
}
const singedUrl = await getURL();
if anyone looking for the whole code please follow this link : https://github.com/harsh4870/Cloud-build-slack-notification/blob/master/singedURL.js

AWS synchronous method wrapping in Task [closed]

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I am currently trying to use the AWS method GetPreSignedURL which doesn't not have a asynchronous alternative. Why would it not provide an asynchronous option?
As this makes an http request which could in theory take a long time, should this operation be be wrapped in a Task to mitigate this and make the application more performant? e.g
public async Task<string> GetPreSignedURL(GetPreSignedUrlRequest request)
{
try
{
return await Task.FromResult(awsClient.GetPreSignedURL())
}
catch (Exception e)
{
// Do something
}
}
This would then be called by something like
await GetPreSignedURL(request)
this makes an http request which could in theory take a long time
^ Here's the misunderstanding.
The HTTP request is not actually performed at this time. What this method does is it takes an HTTP URL (including parameters) and then signs it using your service's credentials. It then returns a new URL that is signed with your credentials, which you can pass elsewhere (e.g., return to your caller). At some point in the future, some other code will issue the actual request using that new URL.
Since your service credentials are already in-memory, and since signing is a CPU operation with no I/O, this operation is properly represented as a synchronous API.

Is it possible to make AWS Websocket + Lambda function to constant monitoring of the DynamoDB and send response to the client?

I have a serverless project: AWS + Angular on the frontend. Currently, I get the data when page is initialized and refresh the data when press "update" button. However, I want to monitor changes in the table constantly. In Firebase there is onSnapShot() method, which sends the new data when a collection is updated.
I want to make something similar with AWS. However, in official documentation, I do not see how to correctly do it.
So here are 2 questions:
How can I connect to the WebSocket with aws-sdk? (Currently, I can connect only from the terminal with wscat -c myurl call. Or shall I simply send http.Post with websocket url?
is it possible to pass invoke in the callback URL? - I want to get data from DynamoDB when page initialize and then invoke it again and again (with a callback URL)
My Lambda function looks like this:
exports.handler = async (event, context) => {
let params = {
TableName: "documents"
}
let respond = await db.scan(params).promise();
return respond;
};
On the front-end I have:
ngOnInit(): void {
AWS.config.credentials = new AWS.Credentials({
accessKeyId: '//mykey', secretAccessKey: '//mysecretkey'
})
AWS.config.update({
region:'//myregion'
})
this.updateTable() // triggers post request to APi Gateway => lambda and receives a response with data.
}
From my understanding, you will need to set up a DynamoDB stream and a lambda function that respond to the database CRUD events, send the updated data to the WebSocket connection if the event data matches the criteria (document id for example), through AWS.ApiGatewayManagementApi. (FYI: https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/ApiGatewayManagementApi.html)

Programmatically invoke a specific endpoint of a webservice hosted on AWS Lambda

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.