Add Name to oauth2.Provider

Providers should be able to tell us their name. This will help construct
routes.

oauth2/github.go

@@ -15,6 +15,21 @@ import (
 
 var _ Provider = &Github{}
 
+// NewGithub constructs a Github with default scopes.
+func NewGithub(clientID, clientSecret string, orgs []string, auth Authenticator, log chronograf.Logger) Github {
+	scopes := []string{"user:email"}
+	if len(orgs) > 0 {
+		scopes = append(scopes, "read:org")
+	}
+	return Github{
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		Orgs:         orgs,
+		Auth:         auth,
+		Logger:       log,
+	}
+}
+
 // Github provides OAuth Login and Callback server. Callback will set
 // an authentication cookie.  This cookie's value is a JWT containing
 // the user's primary Github email address.
@@ -26,6 +41,11 @@ type Github struct {
 	Logger       chronograf.Logger
 }
 
+// Name is the name of the provider
+func (g *Github) Name() string {
+	return "github"
+}
+
 // ID returns the github application client id
 func (g *Github) ID() string {
 	return g.ClientID
@@ -46,21 +66,6 @@ func (g *Github) Scopes() []string {
 	return scopes
 }
 
-// NewGithub constructs a Github with default scopes.
-func NewGithub(clientID, clientSecret string, orgs []string, auth Authenticator, log chronograf.Logger) Github {
-	scopes := []string{"user:email"}
-	if len(orgs) > 0 {
-		scopes = append(scopes, "read:org")
-	}
-	return Github{
-		ClientID:     clientID,
-		ClientSecret: clientSecret,
-		Orgs:         orgs,
-		Auth:         auth,
-		Logger:       log,
-	}
-}
-
 // Config is the Github OAuth2 exchange information and endpoints
 func (g *Github) Config() *oauth2.Config {
 	return &oauth2.Config{

oauth2/oauth2.go

@@ -41,6 +41,9 @@ type Provider interface {
 	Config() *oauth2.Config
 	// PrincipalID with fetch the identifier to be associated with the principal.
 	PrincipalID(provider *http.Client) (string, error)
+
+	// Name is the name of the Provider
+	Name() string
 }
 
 // Mux is a collection of handlers responsible for servicing an Oauth2 interaction between a browser and a provider