Creating and register custom hash driver in AdonisJS v5

.adonisrc.json

{
  "preloads": [
    "./start/hashDriver",
    "./start/routes",
    "./start/kernel"
  ],
}

config-hash.ts

/**
 * Add custom driver to the config file
*/

{
  list: {
    custom: {
      driver: 'custom-bcrypt',
      saltRounds: 10,
    },
  }
}

contracts-hash.ts

/**
 * Contract source: https://git.io/Jfefs
 *
 * Feel free to let us know via PR, if you find something broken in this contract
 * file.
 */

/**
 * Replace `contracts/hash.ts` with this
*/

declare module '@ioc:Adonis/Core/Hash' {
  import { HashDrivers } from '@ioc:Adonis/Core/Hash'

  interface HashersList {
    bcrypt: {
      config: BcryptConfig,
      implementation: BcryptContract,
    },
    custom: {
      config: { saltRounds: number, driver: 'custom-bcrypt' },
      implementation: HashDriverContract,
    }
    argon: {
      config: ArgonConfig,
      implementation: ArgonContract,
    },
  }
}

hashDriver.ts

/*
|--------------------------------------------------------------------------
| Preloaded File
|--------------------------------------------------------------------------
|
| Any code written inside this file will be executed during the application
| boot.
|
*/

/**
* Write this inside `start/hashDriver.ts`
*/

import bcrypt from 'bcrypt'
import Hash, { HashDriverContract } from '@ioc:Adonis/Core/Hash'

/**
 * Implementation of custom bcrypt driver
 */
class CustomBcryptDriver implements HashDriverContract {
  constructor (private config: { saltRounds: number }) {
  }

  /**
   * Ignore these. The PHC format requires it
   */
  public params = {}
  public ids = []

  /**
   * Has to be false, since bcrypt cannot find if password needs
   * a re-hash or not
   */
  public needsReHash () {
    return false
  }

  /**
   * Hash value
   */
  public async hash (value: string) {
    return bcrypt.hash(value, this.config.saltRounds)
  }

  /**
   * Verify value
   */
  public async verify (hashedValue: string, plainValue: string) {
    return bcrypt.verify(plainValue, hashedValue)
  }
}

Hash.extend('custom-bcrypt', function () {
  return new CustomBcryptDriver(arguments[2])
})

@dspangenberg @JonhnyDev
I managed to fix this by adding the following code to contracts/hash.ts

declare module '@ioc:Adonis/Core/Hash' {
  export interface HashDrivers {
    'no-phc-bcrypt': {
      config: { saltRounds: number; driver: 'no-phc-bcrypt' }
      implementation: HashDriverContract
    }
  }
}