nest-user-auth

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This project uses NestJS, GraphQL, and MongoDB.

This project implements user authentication. It will be easy to add other GraphQL schemas following the same structure. User auth is implemented in this project because it is one of the hardest and most common things to create for an API.

The intent of this project is to provide an example of how to integrate all of these technologies together that are in the NestJS documentation (NestJS, GraphQL, MongoDB, Mongoose, Passport, JWT, DotEnv, Joi, Jest) into a working backend. If you recognize an anti-pattern or a better way to do something, please post an issue.

Getting Started

Ensure a MongoDB server is running locally.

Create a development.env file

Add a development.env file to the root of your project.

MONGO_URI=mongodb://localhost:27017/user-auth
JWT_SECRET=someSecret
EMAIL_ENABLED=true
EMAIL_SERVICE=Mailgun
EMAIL_USERNAME=[email protected]
EMAIL_PASSWORD=emailSMTPpassword
EMAIL_FROM=[email protected]

Required Parameters

MONGO_URI the location of your mongo server and database name you want

JWT_SECRET a secret string used to make the keys. Create a random string.

Optional Parameters

MONGO_AUTH_ENABLED set to true if your database requires a username and password. If true, the user specified by MONGO_USER must exist on the database specified in the MONGO_URI option. If true, MONGO_USER and MONGO_PASSWORD are required.

MONGO_USER, MONGO_PASSWORD the user and password for authentication. Recommend a role with readWrite.

JWT_EXPIRES_IN Seconds until token expires. If not set, there will be no expiration.

EMAIL_ENABLED If email services should be used, EMAIL_* fields are required if enabled.

EMAIL_SERVICE Nodemailer "Well Known Service" https://nodemailer.com/smtp/well-known/

EMAIL_USERNAME, EMAIL_PASSWORD Information for the SMTP service. On Mailgun it is the credentials under Domains -> SMTP Credentials. Use the SMTP service, not the API.

EMAIL_FROM The email address the program will use as the from address.

TEST_EMAIL_TO When running tests, where emails will be sent. This should be a real email address you own to verify emails are getting out.

Start the server

npm install

npm run start

That's it, the graphQL playground is found at http://localhost:3000/graphql

Model Management

It is challenging not to repeat the structure of the models in the GraphQL schema, Mongo schema, and Typescript interfaces. The goal is to have one truth point for the models and extend that data when more data is needed.

With NestJS 6.0.0 a code first approach was introduced. This project uses the schema first approach to be language agnostic. The starting point for models is the *.types.graphql files. They contain the GraphQL schema and have properties that every model, at a minimum, should have.

@nestjs/graphql creates a graphql.classes.ts file to match the GraphQL schema when the program is started. These classes are used as the base class for the Mongoose Schema and in place of DTOs. Of note, the IMutation and IQuery classes created by @nestjs/graphql are not extended by the resolver class, though it would be nice if they were. It doesn't appear possible without modification of the grahql.classes.ts file because all the methods aren't implemented in the same resolver.

username is the primary field to identify a user in a request. Initially username or email were accepted, but for simplicity the schema moved to only username. Both username and email fields are in the JWT data, and because they are both unique, either could be used.

The database stores a unique lowercase value for both username and email. This is to lookup the user's username or email without case being a factor. Lowercase username and email are also unique, therefore [email protected] and [email protected] can't both register. The normal cased version is used for everything except lookup. GraphQL Schemas are not aware lowercase values exist intentionally.

The database handles creating the lowercase values with hooks for save and findOneAndUpdate. If another method is used to update or save a User, ensure a hook is created to create the lowercase values.

Users

Add a user via the graphql playground or a frontend. See example mutations and queries below.

Update that user's Document to have the string admin in the permissions array. Only an admin can add another admin, so the first user must be done manually. MongoDB Compass is a great tool to modify fields. That user can now add the admin permission or remove the admin permission to or from other users.

The UsersService update method will update any fields which are valid and not duplicates, even if other fields are invalid or duplicates.

Users can change their username, password, email, or enabled status via a mutation. Changing their username will make their token unusable (it won't authenticate when the user presenting the token's username is checked against the token's username). This may or may not be the desired behavior. If using on a front end, make it obvious that if the user changes their username, it'll log the user out (or the front end must get a new token via logging in behind the scenes - but this would likely require storing the password and is not recommended).

If a user sets enabled to false on their account, they cannot log back in (because it is disabled), only an admin can change it back.

Because both unique properties username and email can be changed, _id should be used as keys for relationships.

See test/users.e2e-spec.ts for expected results to mutations and queries.

Environments

Add a test.env file which contains a different MONGO_URI than development.env. See the testing section for details.

Add any other environments for production and test. The environment variable NODE_ENV is used to determine the correct environment to work in. The program defaults to development if there is not a NODE_ENV environment variable set. For example, if the configuration is stored in someEnv.env file in production then set the NODE_ENV environment variable to someEnv. This can be done through package.json scripts, local environment variables, or your launch.json configuration in VS Code. If you do nothing, it will look for development.env. Do not commit this file.

Authentication

Add the token to your headers {"Authorization": "Bearer eyj2aGc..."} to be authenticated via the JwtAuthGuard.

If a user's account property enabled is set to false, their token will no longer authenticate. Many critiques of JWTs vs. session based authentication solutions are that a JWT cannot be invalidated once issued. While that is true, no request will authenticate with a valid JWT while the account associated with the token's enabled field is false. An admin or the user can set that field via an update.

Admin must be set manually as a string in permissions for the first user (add admin to the permissions array). That person can then add admin to other users via a mutation. Permissions is an array of strings so that other permissions can be added to allow custom guards.

Users can modify or view their own data. Admins can do anything except refresh another user's token or change their password, which would allow the admin to impersonate that user.

The UsernameEmailGuard compares the user's email or username with the same field in a query. If any query or mutation in the resolver has doAnythingWithUser(username: string) or doAnythingWithUser(email: string) and that email / username matches the user which is requesting the action, it will be approved. Username and email are unique, and the user has already been verified via JWT. If there is not a username or email in the request, it will pass. This is because the resolvers will set the action on the user making the request. For example, on updateUser if no username is specified, the modification is on the user making the request.

The UsernameEmailAdminGuard is the same as the UsernameEmailGuard except it also allows admins. Admins should not be allowed to change everything. For example, an admin should not be allowed to set another user's password. This would allow the admin to impersonate that user. The @AdminAllowedArgs decorator has been added for this reason to this guard. If this decorator is used, only the arguments specified are allowed. Placing the below decorator above the updateUser resolver will not allow an admin to specify the fieldsToUpdate.password argument.

@AdminAllowedArgs(
    'username',
    'fieldsToUpdate.username',
    'fieldsToUpdate.email',
    'fieldsToUpdate.enabled',
  )

The AdminGuard only allows admins.

The JwtAuthGuard ensures that there is a valid JWT and that the user associated with the JWT exists in the database.

The User's Document is accessable in the resolver via @Context('req') should it be needed. For example, a user creates a Purchase and that user's ID needs to be attached to the purchase. An example mutation is shown below.

  // This is an example of how to get access to the validated user making the request
  @UseGuards(JwtAuthGuard)
  @Mutation('userInResolver')
  userInResolver(@Context('req') request: any) {
    const user: UserDocument = request.user;
  }

Relationships

To add a relationship with the NestJS Schema first approach and Mongoose there are a few caveats. Take for example a one-to-many relationship where a Purchase can be made by one user, but a user can have many purchases. Likely, the Purchase GraphQL schema will look like this:

type Purchase {
  product: String!
  customer: User!
  ...
}

This allows a user to make a query that contains both the purchase and its customer's subfields (see below for security concerns). The Schema first approach will create a file that contains the Purchase class, as defined by the schema above, with the customer property of type User. For the MongoDB Schema and Document, a different field for the foreign key must be created. For example:

export interface PurchaseDocument extends Purchase, Document {
// Declaring properties that are not in the GraphQL Schema for a Purchase
  customerId: Types.ObjectId;
}

export const PurchaseDocument: Schema = new Schema(
  {
    ...,
    customerId: {
      type: Types.ObjectId,
      ref: 'User',
    },
  })

The customerId property of the PurchaseDocument interface can reference the ObjectId and the customer property of the Purchase class can reference the User class. The Purchase class as defined by the schema only has a customer property, while the PurchaseDocument has both the customer and customerId properties. This makes sense because a user should never care about how the relationship is built. Below is an example of how the customer's information, including ID, can be queried.

@ResolveProperty()
async customer(@Parent() purchase: PurchaseDocument): Promise<User> {
  const userDocument = await this.usersService.findOneById(comment.customerId);
  return userDocument;
}

query purchase {
  purchase(id: "35") {
    price
    customer {
      username
    }
  }
}

Keep in mind, the above example would create a security issue as every field of a User would be accessable to anyone querying a Location. To fix this, add a new type to the GraphQL schema such as SanitizedUser which contains only public fields. Then, the Purchase.customer property would be changed from User to SanitizedUser.

It would be nice to have the customer property be a union of a MongoId and User. This would allow Mongoose's populate method to be used to replace the MongoId with a User. However, a property cannot be made more generic when extending a class.

Testing

To test, ensure that the environment is different than the development environment. When the end to end tests run, they will delete all users in the database specified in the environment file on start. Currently running npm run test:e2e will set NODE_ENV to test based on package.json scripts. This will default to the test.env file.

Create test.env to have a different database than the development.env file. To test Nodemailer include the variable TEST_EMAIL_TO which is the email that will receive the password reset email.

Example test.env

MONGO_URI=mongodb://localhost:27017/user-auth-test
JWT_SECRET=someSecret
EMAIL_SERVICE=Mailgun
EMAIL_USERNAME=[email protected]
EMAIL_PASSWORD=emailSMTPpassword
EMAIL_FROM=[email protected]
TEST_EMAIL_TO=[email protected]

nodemon

To use nodemon there is a small change required. Because the classes file is built from the schema, it is recreated on each launch. This causes nodemon to restart on a loop. Add src/graphql.classes.ts to the ignore array in nodemon.json to ignore the changes to that file.

{
  "ignore": ["src/**/*.spec.ts", "src/graphql.classes.ts"],
}

Next tasks

Add email verification when a user registers.

GraphQL Playground Examples

query loginQuery($loginUser: LoginUserInput!) {
  login(user: $loginUser) {
    token
    user {
      username
      email
    }
  }
}

{
  "loginUser": {
    "username": "usersname",
    "password": "passwordOfUser"
  }
}

query {
  users {
    username
    email
  }
}

query user {
  user(email: "[email protected]") {
    username
  }
}

query refreshToken {
  refreshToken
}

mutation updateUser($updateUser: UpdateUserInput!) {
  updateUser(username: "usernametoUpdate", fieldsToUpdate: $updateUser) {
    username
    email
    updatedAt
    createdAt
  }
}

{
  "updateUser": {
    "username": "newUserName",
    "email": "[email protected]",
    "enabled": false
  }
}

mutation CreateUser {
  createUser(
    createUserInput: {
      username: "username"
      email: "[email protected]"
      password: "userspassword"
    }
  ) {
    username
  }
}

mutation {
  addAdminPermission(username: "someUsername") {
    permissions
  }
}

mutation {
  removeAdminPermission(username: "someUsername") {
    permissions
  }
}

query {
  forgotPassword(email: "[email protected]")
}

mutation {
  resetPassword(
    username: "username"
    code: "code-from-the-email"
    password: "password"
  ) {
    username
  }
}