JWT Authentication

Jump to Section

In case you decide to use JWT as your Auth* of choice, Mortar have a simple Token Extractor.

type TokenExtractor interface {
	// FromContext should try to extract a token from the Context using `ContextExtractor`
	FromContext(ctx context.Context) (Token, error)
	// FromString accepts a JWT token in form of a string
	//	xxxxx.yyyyy.zzzzz
	FromString(str string) (Token, error)
}

Mortar and gRPC-Gateway

Usually you pass the JWT Token via the Authorization header

Authorization: bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Now, you are encouraged to use gRPC-Gateway, but in this case you don’t really have an access to HTTP Request Headers. Fear not, gRPC-Gateway and Mortar have your covered.

By default gRPC-Gateway will transform this special Authorization header into grpcgateway-authorization and put it in the Context.
Mortar have a DefaultJWTTokenExtractor that takes care of that.

Example

You only need to register Token Extractor by providing DefaultJWTTokenExtractor constructor to Uber-Fx.

import (
 "github.com/go-masonry/mortar/constructors"
 "go.uber.org/fx"
)
...
fx.Provide(constructors.DefaultJWTTokenExtractor)
...

Once provided, you can inject TokenExtractor and use it

type authDeps struct {
 fx.In

 TokenExtractor jwt.TokenExtractor
}
...

func (impl *authImpl) CheckJWT(ctx context.Context) error {
 // we only log for error here
 token, err := impl.deps.TokenExtractor.FromContext(ctx)
 if err != nil {
     return fmt.Errorf("no jwt token found, %w",err)
 }
 m, err = token.Map()
 if err != nil {
   return fmt.Errorf("failed to produce a map from authorization header, %w", err)
 }
 ...
 ...
 return nil
}

Mortar service template have a simple working example. Look at app/validations/auth.go.

Mortar Design