AWS SNS not attaching a Lambda trigger when the subscription is created via the SDK-CodePudding

I want to use a SNS subscription to trigger a Lambda function. First I have created a topic and subscription via the AWS SDK:

    import {SubscribeCommand } from "@aws-sdk/client-sns";
    import {snsClient } from "./libs/snsClient.js";

    // Set the parameters
    const params = {
      Protocol: "lambda" /* required */,
      TopicArn: "TOPIC_ARN", //TOPIC_ARN
      Endpoint: "LAMBDA_FUNCTION_ARN", //LAMBDA_FUNCTION_ARN
    };

    const run = async () => {
      try {
        const data = await snsClient.send(new SubscribeCommand(params));
        console.log("Success.",  data);
        return data; // For unit tests.
      } catch (err) {
        console.log("Error", err.stack);
      }
    };
    run();

It is creating the subscription, but when I check the Lambda, this sub is not appearing as a Lambda trigger.

When I create the subscription manually without using the SDK it's working.

I would like to know why my subscription that created with the SDK is not showing in the Lambda's trigger.

CodePudding user response：

Looks like you are missing the IAM permissions. SNS needs explicit permission to invoke your Lambda.

See How do I subscribe a Lambda function to an Amazon SNS topic in the same account? in the docs. The lambda add-permission CLI step from the example is the same as the AddPermissionCommand in the SDK Lambda client. Provide your SNS topic's ARN.