fastify.register(require('fastify-bcrypt'), {
  saltWorkFactor: 12
})

fastify.bcrypt.hash('password')
  .then(hash => fastify.bcrypt.compare('password', hash))
  .then(match => console.log(match ? 'Matched!' : 'Not matched!'))
  .catch(err => console.error(err.message))

// Matched!