2.1.1 • Public • Published

Fastify Secrets (core)


Simplify development of fastify-secrets plugins

This module is intended for developers implementing fastify-secrets plugins, not for developers using fastify-plugin in their fastify projects


npm install --save fastify-secrets-core


fastify-secrets-core simplifies development of fastify-secrets plugins and ensures that all plugins implements the same api.

Each plugin must only provide a simple client that interacts with the secrets storage and fastify-secrets-core will glue it to fastify.


Create a new fastify plugin by calling buildPlugin and providing a client class or constructor and options that will be forwarded to fastify-plugin.

buildPlugin will return a fastify plugin that can be exported.


const { buildPlugin } = require('fastify-secrets-core')
const Client = require('./client')

const plugin = buildPlugin(Client, {
  name: 'fastify-secrets-example'


The client that needs to be provided to fastify-secrets-core should implement this methods:

  • constructor
  • async get(ref) (required) This will be called to fetch a single secret identified by reference. It's up to the implementation what ref is.
  • async close() (optional) This method will be called, if present, when the plugin is done fetching the secrets to give a chance to implementations to close any connection or run any teardown code. No further calls to the get method will be run after close.


This is a basic client implementation that reads secrets from process.env

class Client {
  constructor() {
    console.log('client contructor')

  async get(ref) {
    return process.env[ref]

  async close() {
    console.log('client close')

Resulting plugin

The resulting plugin can be registered directly in fastify. These are the available options:

  • secrets (required). A non-empty object representing a map of secret keys and references, or an array of strings. The plugin will decorate fastify with a secrets object with the same keys as this option (for object values) or with the same keys as the array elements (for array values) but will replace the references with the actual values for the secret as fetched with client.get(reference)
  • namespace (optional). If present, the plugin will add the secret values to fastify.secrets.namespace instead of fastify.secrets.
  • concurrency (optional, defaults to 5). How many concurrent call will be made to client.get. This is handled by fastify-secrets-core and it's transparent to the implementation.
  • clientOptions (optional). A value that will be provided to the constructor of the Client. Useful to allow plugin users to customize the plugin.

The plugin will also expose the original Client for uses outside of fastify (i.e. db migrations and scripts)


Assuming a plugin is built as per the previous examples, it can be used as:

fastify.register(plugin, {
  namespace: 'db',
  concurrency: 5,
  secrets: {
    user: 'PG_USER',
    pass: 'PG_PASS'
  clientOptions: {
    optional: 'value'

await fastify.ready()


Or, with an array secrets option:

fastify.register(plugin, {
  namespace: 'db',
  concurrency: 5,
  secrets: ['PG_USER', 'PG_PASS'],
  clientOptions: {
    optional: 'value'

await fastify.ready()


Refreshing Secrets

In the event secrets need to be dynamically refreshed, a refresh method is exposed to allow for the refreshing of single, sets, or all secrets scoped to the provided namespace. The signature of the refresh method is as follows:

async refresh(refs)

  • refs (optional). refs can be a single secret, an array of secrets, or left undefined to refresh all secrets belonging to the namespace.

The most basic example of usage can be seen below,

fastify.register(plugin, {
  secrets: ['TOKEN']

await fastify.ready()

const refreshedSecrets = await fastify.secrets.refresh() // { 'TOKEN': 'refreshed value' }

When working with multiple secret providers, it is highly recommended that you scope your secrets by a namespace, this will prevent conflicts with other secret providers and allow for more atomic refreshing if necessary. Note the example below for usage, in particular the refresh method is exposed on the registered namespace and not at the root of the secrets object.

fastify.register(plugin, {
  namespace: 'aws',
  secrets: ['TOKEN']

await fastify.ready()

const refreshedSecrets = await // { 'TOKEN': 'refreshed value' }
Refresh Aliasing

It's possible that a secret name may conflict with the refresh method, in the event this happens you can supply an alias for the refresh function in order to avoid conflicts.

fastify.register(plugin, {
  secrets: ['TOKEN'],
  namespace: 'auth',
  refreshAlias: 'update'

await fastify.ready()

const refreshedSecrets = await fastify.secrets.update() // { 'TOKEN': 'refreshed value' }




Copyright NearForm Ltd 2020. Licensed under the Apache-2.0 license.


npm i fastify-secrets-core

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