Auth (#1147)

Implement the Auth interface, with JWT and service implementations.

* Update Auth Interface

* Define Auth Service Implementation

* Support Service Auth

* Add Auth Service Proto

* Remove erronious files

* Implement Auth Service Package

* Update Auth Interface

* Update Auth Interface. Add Validate, remove Add/Remove roles

* Make Revoke interface more explicit

* Refactor serializing and deserializing service accounts

* Fix srv name & update interface to be more explicit

* Require jwt public key for auth

* Rename Variables (Resource.ID => Resource.Name & ServiceAccount => Account)

* Implement JWT Auth Package

* Remove parent, add ID

* Update auth imports to v2. Add String() to auth interface

auth/jwt/jwt.go

@@ -0,0 +1,106 @@
+package jwt
+
+import (
+	"errors"
+	"time"
+
+	"github.com/dgrijalva/jwt-go"
+	"github.com/micro/go-micro/v2/auth"
+)
+
+// ErrInvalidPrivateKey is returned when the service provided an invalid private key
+var ErrInvalidPrivateKey = errors.New("An invalid private key was provided")
+
+// ErrEncodingToken is returned when the service encounters an error during encoding
+var ErrEncodingToken = errors.New("An error occured while encoding the JWT")
+
+// ErrInvalidToken is returned when the token provided is not valid
+var ErrInvalidToken = errors.New("An invalid token was provided")
+
+// NewAuth returns a new instance of the Auth service
+func NewAuth(opts ...auth.Option) auth.Auth {
+	svc := new(svc)
+	svc.Init(opts...)
+	return svc
+}
+
+// svc is the JWT implementation of the Auth interface
+type svc struct {
+	options auth.Options
+}
+
+func (s *svc) String() string {
+	return "jwt"
+}
+
+func (s *svc) Init(opts ...auth.Option) error {
+	for _, o := range opts {
+		o(&s.options)
+	}
+
+	return nil
+}
+
+// AuthClaims to be encoded in the JWT
+type AuthClaims struct {
+	Id       string            `json:"id"`
+	Roles    []*auth.Role      `json:"roles"`
+	Metadata map[string]string `json:"metadata"`
+
+	jwt.StandardClaims
+}
+
+// Generate a new JWT
+func (s *svc) Generate(id string, ops ...auth.GenerateOption) (*auth.Account, error) {
+	key, err := jwt.ParseRSAPrivateKeyFromPEM(s.options.PrivateKey)
+	if err != nil {
+		return nil, ErrEncodingToken
+	}
+
+	options := auth.NewGenerateOptions(ops...)
+	account := jwt.NewWithClaims(jwt.SigningMethodRS256, AuthClaims{
+		id, options.Roles, options.Metadata, jwt.StandardClaims{
+			Subject:   "TODO",
+			ExpiresAt: time.Now().Add(time.Hour * 24).Unix(),
+		},
+	})
+
+	token, err := account.SignedString(key)
+	if err != nil {
+		return nil, err
+	}
+
+	return &auth.Account{
+		Id:       id,
+		Token:    token,
+		Roles:    options.Roles,
+		Metadata: options.Metadata,
+	}, nil
+}
+
+// Revoke an authorization account
+func (s *svc) Revoke(token string) error {
+	return nil
+}
+
+// Validate a JWT
+func (s *svc) Validate(token string) (*auth.Account, error) {
+	res, err := jwt.ParseWithClaims(token, &AuthClaims{}, func(token *jwt.Token) (interface{}, error) {
+		return jwt.ParseRSAPublicKeyFromPEM(s.options.PublicKey)
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	if !res.Valid {
+		return nil, ErrInvalidToken
+	}
+
+	claims := res.Claims.(*AuthClaims)
+
+	return &auth.Account{
+		Id:       claims.Id,
+		Metadata: claims.Metadata,
+		Roles:    claims.Roles,
+	}, nil
+}