Firebase Custom Tokens

firebase.go

package firebase

import (
	"github.com/knq/jwt"
	"github.com/knq/jwt/gserviceaccount"
	"time"
)

// Firebase JWT Claims
type Claims struct {
	Iss string `json:"iss"`
	Sub string `json:"sub"`
	Aud string `json:"aud"`
	Iat int64  `json:"iat"`
	Exp int64  `json:"exp"`
	Uid string `json:"uid"`
}

// Firebase App
type App struct {
	GServiceAccount *gserviceaccount.GServiceAccount
}

// Issue custom JWT token used for client login.
func (app *App) CustomToken(uid string) ([]byte, error) {
	signer, err := app.GServiceAccount.Signer()
	if err != nil {
		return nil, err
	}
	now := time.Now().Unix()
	return jwt.Encode(jwt.RS256, signer, Claims{
		Iss: app.GServiceAccount.ClientEmail,
		Sub: app.GServiceAccount.ClientEmail,
		Aud: "https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit",
		Iat: now,
		Exp: now + 60*60,
		Uid: uid,
	})
}