---
id: dev-plugins
title: "Developing Plugins"
---
There are many ways to extend `verdaccio`, currently we support `authentication plugins`, `middleware plugins` (since `v2.7.0`) and `storage plugins` since (`v3.x`).

## Authentication Plugin

This section will describe how it looks like a Verdaccio plugin in a ES5 way. Basically we have to return an object with a single method called `authenticate` that will recieve 3 arguments (`user, password, callback`). Once the authentication has been executed there is 2 options to give a response to `verdaccio`.

### API

```js
function authenticate (user, password, callback) {
 ...more stuff
}
```

##### OnError

Either something bad happened or auth was unsuccessful.

    callback(null, false)
    

##### OnSuccess

The auth was successful.

`groups` is an array of strings where the user is part of.

     callback(null, groups);
    

### Example

```javascript
function Auth(config, stuff) {
  var self = Object.create(Auth.prototype);
  self._users = {};

  // config for this module
  self._config = config;

  // verdaccio logger
  self._logger = stuff.logger;

  // pass verdaccio logger to ldapauth
  self._config.client_options.log = stuff.logger;

  return self;
}

Auth.prototype.authenticate = function (user, password, callback) {
  var LdapClient = new LdapAuth(self._config.client_options);
  ....
  LdapClient.authenticate(user, password, function (err, ldapUser) {
    ...
    var groups;
     ...
    callback(null, groups);
  });
};

module.exports = Auth;
```

And the setup

```yaml
auth:
  htpasswd:
    file: ./htpasswd
```

Where `htpasswd` is the sufix of the plugin name. eg: `verdaccio-htpasswd` and the rest of the body would be the plugin configuration params.

## Middleware Plugin

Middleware plugins have the capability to modify the API layer, either adding new endpoints or intercepting requests.

> A pretty good example of middleware plugin is the [sinopia-github-oauth](https://github.com/soundtrackyourbrand/sinopia-github-oauth) and [verdaccio-audit](https://github.com/verdaccio/verdaccio-audit).

### API

```js
function register_middlewares(expressApp, authInstance, storageInstance) {
   /* more stuff */
}
```

To register a middleware we need an object with a single method called `register_middlewares` that will recieve 3 arguments (`expressApp, auth, storage`). *Auth* is the authentification instance and *storage* is also the main Storage instance that will give you have access to all to the storage actions.

## Storage Plugin

Verdaccio by default uses a file system storage plugin [local-storage](https://github.com/verdaccio/local-storage) but, since `verdaccio@3.x` you can plug in a custom storage.

### API

The storage API is a bit more complex, you will need to create a class that return a `ILocalData` implementation. Please see details bellow.

```js
<br />class LocalDatabase<ILocalData>{
    constructor(config: Config, logger: Logger): ILocalData;
}

declare interface verdaccio$ILocalData {
  add(name: string, callback: verdaccio$Callback): void;
  remove(name: string, callback: verdaccio$Callback): void;
  get(callback: verdaccio$Callback): void;
  getSecret(): Promise<string>;
  setSecret(secret: string): Promise<any>;
  getPackageStorage(packageInfo: string): verdaccio$IPackageStorage;
}

declare interface verdaccio$ILocalPackageManager {
  writeTarball(name: string): verdaccio$IUploadTarball;
  readTarball(name: string): verdaccio$IReadTarball;
  readPackage(fileName: string, callback: verdaccio$Callback): void;
  createPackage(name: string, value: verdaccio$Package, cb: verdaccio$Callback): void;
  deletePackage(fileName: string, callback: verdaccio$Callback): void;
  removePackage(callback: verdaccio$Callback): void;
  updatePackage(pkgFileName: string,
                updateHandler: verdaccio$Callback,
                onWrite: verdaccio$Callback,
                transformPackage: Function,
                onEnd: verdaccio$Callback): void;
  savePackage(fileName: string, json: verdaccio$Package, callback: verdaccio$Callback): void;
}

interface IUploadTarball extends stream$PassThrough {
  abort(): void;
  done(): void;
}

interface IReadTarball extends stream$PassThrough {
  abort(): void;
  done(): void;
}
```

> The Storage API is still experimental and might change in the next minor versions. For further information about Storage API please follow the [types definitions in our official repository](https://github.com/verdaccio/flow-types).

### Storage Plugins Examples

The following list of plugins are implementing the Storage API and might be used them as example.

* [verdaccio-memory](https://github.com/verdaccio/verdaccio-memory)
* [local-storage](https://github.com/verdaccio/local-storage)
* [verdaccio-google-cloud](https://github.com/verdaccio/verdaccio-google-cloud)
* [verdaccio-s3-storage](https://github.com/Remitly/verdaccio-s3-storage/tree/s3)

> Are you willing to contribute with new Storage Plugins? [Click here.](https://github.com/verdaccio/verdaccio/issues/103#issuecomment-357478295)