PAM authentication failed for user \"db_iamuser\"

Question

I have a postgres instance on AWS RDS. This instance allows you to connect to it using IAM authentication. I also have a lambda function that executes various queries defined in a separate file from the function implementation. This function is executed when calling an endpoint defined in API Gateway.

File with queries implementation:

const { Pool } = require("pg");
const region = process.env.REGION;

const signer = new aws.RDS.Signer({
  region: process.env.REGION,
  hostname: process.env.PG_HOST,
  port: 5432,
  username: "db_iamuser",
});

const pool = new Pool({
  user: "db_iamuser",
  host: process.env.PG_HOST,
  database: process.env.PG_DATABASE,
  port: 5432,
  ssl: {
    rejectUnauthorized: false,
  },
  password: () => signer.getAuthToken(),
});

async function destroy() {
  await pool.end().then(() => console.log("DB Connection ended"));
}

async function getInfo1() {
  const query = `SELECT field1, field2 FROM public.table1`;
  try {
    const response = await pool.query(query);
    return response.rows;
  } catch (error) {
    throw error;
  }
}

async function getInfo2() {
  const query = `SELECT field1, field2 FROM public.table2`;
  try {
    const response = await pool.query(query);
    return response.rows;
  } catch (error) {
    throw error;
  }
}

async function getInfo3() {
  const query = `SELECT field1, field2 FROM public.table3`;
  try {
    const response = await pool.query(query);
    return response.rows;
  } catch (error) {
    throw error;
  }
}

module.exports = {
  getInfo1,
  getInfo2,
  getInfo3,
};

In the same function I create a user in AWS Cognito.

const { Responses } = require("../../libs/response");
const {
  getInfo1,
  getInfo2,
  getInfo3,
} = require("../../libs/queries");
const { CognitoService } = require("../../libs/cognito");

exports.handler = async function (event, context) {

  const { Authorization } = event.headers;
  const user = JSON.parse(event.body);
  
  try {
    console.log("Getting Info1 ");
    const info1 = await getInfo1();
    console.log("Getting Info2 ");
    const info1 = await getInfo2();
    console.log("Getting Info3 ");
    const info1 = await getInfo3();

    //... Creating user in Cognito
    await provider
      .adminCreateUser(request)
      .promise();


    await provider
        .adminAddUserToGroup({ request, GroupName })
        .promise();
      
    return Responses._200({ });
    
  } catch (error) {
    console.log("Error ", error);
    throw error;
  }
};

When I call the endpoint that executes the lambda function, the queries are executed without problems.

However, if I call again and immediately the endpoint throws me this error:

PAM authentication failed for user \"db_iamuser\"

Note: I isolated the queries in a lambda function that will not perform any actions in Cognito and it works every time I call it.

Please someone help me understand why this happens.

PAM authentication failed for user \"db_iamuser\"

0 Answers