Add base_url option to GitHub auth provider to allow selecting a custom endpoint. Fixes #572.

builtin/credential/github/path_login.go

@@ -1,6 +1,9 @@
 package github
 
 import (
+	"fmt"
+	"net/url"
+
 	"github.com/google/go-github/github"
 	"github.com/hashicorp/vault/logical"
 	"github.com/hashicorp/vault/logical/framework"
@@ -39,6 +42,14 @@ func (b *backend) pathLogin(
 		return nil, err
 	}
 
+	if config.BaseURL != "" {
+		parsedURL, err := url.Parse(config.BaseURL)
+		if err != nil {
+			return nil, fmt.Errorf("Successfully parsed base_url when set but failing to parse now: %s", err)
+		}
+		client.BaseURL = parsedURL
+	}
+
 	// Get the user
 	user, _, err := client.Users.Get("")
 	if err != nil {
@@ -108,7 +119,6 @@ func (b *backend) pathLogin(
 		}
 	}
 
-
 	policiesList, err := b.Map.Policies(req.Storage, teamNames...)
 	if err != nil {
 		return nil, err