Middy RDS Middleware

RDS provides seamless connection with database of your choice.

After initialization your database connection is accessible under:

middy((event, context) => {
  const { sql } = context
})

Mind that if you use knex you will also need driver of your choice (check docs), for PostgreSQL that would be:

yarn add {pg,postgres}
// or
npm install {pg,postgres}

Install

To install this middleware you can use NPM:

npm install --save middy-rds
npm install --save-dev @aws-sdk/rds-signer

Requires: @middy/core:>=4.0.0

Options

• client (function) (required): client that you want to use when connecting to database of your choice. Designed to be used by knex.js. However, as long as your client is run as client(config), you can use other tools.
• config (object) (required): configuration object passed as is to client (knex.js recommended), for more details check knex documentation
• forceConnection (boolean) (default false): After creating the database client call SELECT 1 to for a connection to be opened
• internalData (object) (optional): Pull values from middy internal storage into config.connection object.
• cacheKey (string) (default rds): Cache key for the fetched data responses. Must be unique across all middleware.
• cachePasswordKey (string) (default rds):Cache key for the fetched data response related to the password. Must match the cacheKey for the middleware that stores it.
• cacheExpiry (number) (default -1): How long fetch data responses should be cached for. -1: cache forever, 0: never cache, n: cache for n ms.

Note:

• config.connection defaults to:

{
  ssl: {
    rejectUnauthorized: true,
    ca, // readFile(process.env.NODE_EXTRA_CA_CERTS)
    checkServerIdentity: (host, cert) => {
      const error = tls.checkServerIdentity(host, cert)
      if (error && !cert.subject.CN.endsWith('.rds.amazonaws.com')) {
         return error
      }
    }
  }
}

If your lambda is timing out, likely your database connections are keeping the event loop open. Check out do-not-wait-for-empty-event-loop middleware to resolve this.

Sample usage

Minimal configuration

pg

import rdsMiddleware from 'middy-rds/pg'

import capturePostgres from 'aws-xray-sdk-postgres'
import pgClient from 'pg'

const pg = capturePostgres(pgClient)

const handler = middy(async (event, context) => {
  const { sql } = context
  const records = await sql.select('*').from('my_table')
  console.log(records)
}).use(
  rdsMiddleware({
    client: pg.Pool,
    config: {
      host: '*.ca-central-1.rds.amazonaws.com',
      user: 'iam_role',
      database: 'postgres',
      application_name: process.env.AWS_LAMBDA_FUNCTION_NAME
    }
  })
)

knex

import rdsMiddleware from 'middy-rds/knex'
import knex from 'knex'

import capturePostgres from 'aws-xray-sdk-postgres'
import pgClient from 'pg'

const pg = capturePostgres(pgClient)

const handler = middy(async (event, context) => {
  const { sql } = context
  const records = await sql.select('*').from('my_table')
  console.log(records)
}).use(
  rdsMiddleware({
    client: knex,
    config: {
      client: 'pg',
      connection: {
        host: '*.ca-central-1.rds.amazonaws.com',
        user: 'iam_role',
        database: 'postgres',
        port: 5432,
        application_name: process.env.AWS_LAMBDA_FUNCTION_NAME
      }
    }
  })
)

postgres

import rdsMiddleware from 'middy-rds/postgres'

import postgresClient from 'postgres'

const handler = middy(async (event, context) => {
  const { sql } = context
  const records = await sql`SELECT * FROM my_table`
  console.log(records)
}).use(
  rdsMiddleware({
    client: postgresClient,
    config: {
      host: '*.ca-central-1.rds.amazonaws.com',
      user: 'iam_role',
      database: 'postgres',
      connection: {
        application_name: process.env.AWS_LAMBDA_FUNCTION_NAME
      }
    }
  })
)

Using with docker

# https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/UsingWithRDS.SSL.html
ADD https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem /path/to/save/
ENV NODE_EXTRA_CA_CERTS=/path/to/save/global-bundle.pem

Middy documentation and examples

For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.

Contributing

Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.

License

Licensed under MIT License. Copyright (c) 2017-2022 will Farrell and the Middy team.