Sample Fastify Plugin to connect to MariaDB/MySql

db.js

'use strict'

const fp = require('fastify-plugin')
const mysql = require('mysql2/promise')

const CONNECTION_STRING = process.env.DB_CONN_STRING

module.exports = fp(async function (fastify, opts) {
  const db = await mysql.createConnection(CONNECTION_STRING)

  fastify.decorate('db', db)

  fastify.addHook('onClose', async function () {
    return db.end()
  })

  fastify.log.info(`Database connected to "${db.connection.config.host}:${db.connection.config.port}" as "${db.connection.config.user}"`)
})

example_route.js

'use strict'

module.exports = async function (fastify, opts) {
  fastify.get('/some-data', async function (request, reply) {
    let data = await fastify.db.execute(
      'SELECT * FROM someTable LIMIT 10'
    )
    
    return data
  })
}