How to renew connection of database for iam authentication - aws-sdk

Question

Using IAM database authentication the password expires after about 15 minutes. So I ideally have to renew the database connection before the password expires. I set up a timer on the first initialization of the database and query the passed time on each query. How can i refresh the password of the connection before the password expires? Or how can i destroy the old database object and renew the object if necessary?
The error message is: "PAM authentication failed for user iam_user".
code for getting IAM Password:
const pgp = require('pg-promise')();
const AWS = require('aws-sdk');
const ca =
'-----BEGIN CERTIFICATE-----\nMIID9DCCAtyg...
...wZfTUU=\n-----END CERTIFICATE-----\n';
const signer = new AWS.RDS.Signer({
region: process.env.REGION,
username: process.env.DATABASE_USER,
hostname: process.env.DATABASE_HOST,
port: parseInt(`${process.env.DATABASE_PORT}`, 10),
});
module.exports = pgp({
host: process.env.DATABASE_HOST,
port: process.env.DATABASE_PORT,
database: process.env.DATABASE_NAME,
user: process.env.DATABASE_USER,
ssl: { ca },
dialectOptions: { ssl: { require: true } },
password: signer.getAuthToken(),
});
injecting db object to graphql:
const db = require('../db/init');
server.use(
mount(
'/graphql',
graphqlHTTP( () => ({
schema: schema,
context: { startTime: Date.now(), db },
graphiql: true
})),
),
);
Using the database in the resolvers.
I could query the time of the creation of the database connection. Is there a possibility to renew the password if necessary? Or what is the best way to destroy the old database object and create a new database object?
const resolvers = {
Query: {
Post: (root, args, {db}) => {
console.log(args.id);
console.log(db.$config.options)
const postQuery = new PQ({
text:
'SELECT post_id as id FROM tbl_post where post_id = $1',
values: [parseInt(args.id, 10)],
});
return db.one(postQuery).catch((err) => console.log(err));
}
}

Answer 1

As suggested by vitaly-t i used a password function. To avoid adding latency this functions renews the password only every 15 minutes. If the pool gets continuously used in intervals lower than 10 seconds, than the connection stays open without calling the password function at all. According to my tests there are no new connections to the database opened at all.
const ca = '-----BEGIN CERTIFICATE-----\9DC...-----END CERTIFICATE-----\n';
const signer = new AWS.RDS.Signer({
region: process.env.REGION,
username: process.env.DATABASE_USER,
hostname: process.env.DATABASE_HOST,
port: parseInt(`${process.env.DATABASE_PORT}`, 10),
});
const SIGNER = { time: 0, password: undefined};
function getSignedPassword() {
const time = Date.now();
if (time - SIGNER.time > 900000) {
SIGNER.time = new Date().getTime();
SIGNER.password = signer.getAuthToken();
return SIGNER.password;
}
return SIGNER.password;
}
module.exports = pgp({
host: process.env.DATABASE_HOST,
port: process.env.DATABASE_PORT,
database: process.env.DATABASE_NAME,
user: process.env.DATABASE_USER,
ssl: { ca },
password: getSignedPassword,
});