From 75afff0b1447fb849cb1bc4ad2b877648e97bf42 Mon Sep 17 00:00:00 2001
From: Daniel Kerwin <daniel@gini.net>
Date: Wed, 27 Nov 2019 10:55:39 +0100
Subject: [PATCH] Support build time provider specification

---
 Makefile    |  3 ++-
 README.md   |  8 ++++++++
 cmd/auth.go | 22 ++++++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 36bef6a..df3c9e2 100644
--- a/Makefile
+++ b/Makefile
@@ -86,7 +86,8 @@ bin/$(ARCH)/$(BIN):
 	    -X $(PKG)/version.GITHASH=$(GIT_HASH) \
 	    -X $(PKG)/version.DOB=$(DOB) \
 	    -X $(PKG)/cmd.buildTimeClientID=$(CLIENT_ID) \
-	    -X $(PKG)/cmd.buildTimeClientSecret=$(CLIENT_SECRET)"
+	    -X $(PKG)/cmd.buildTimeClientSecret=$(CLIENT_SECRET) \
+	    -X $(PKG)/cmd.buildTimeProvider=$(DEFAULT_PROVIDER)"
 
 # Run go vet on repo
 vet:
diff --git a/README.md b/README.md
index bed74d7..810435e 100644
--- a/README.md
+++ b/README.md
@@ -69,6 +69,14 @@ It is possible to embed your Google credentials into the resulting binary.
 CLIENT_ID=abc123.apps.googleusercontent.com CLIENT_SECRET=mySecret OS=linux make
 ```
 
+You can streamline your user experience even more by also specifying a
+default provider. `dexter auth` will then run the specified provider.
+Valid choices are `google` and `azure`.
+
+```
+DEFAULT_PROVIDER=google make
+```
+
 ## Run dexter
 
 Run `dexter` without a command to access the help screen/intro.
diff --git a/cmd/auth.go b/cmd/auth.go
index 20ee19c..c31c869 100644
--- a/cmd/auth.go
+++ b/cmd/auth.go
@@ -32,6 +32,7 @@ var (
 	// default injected at build time. This is optional
 	buildTimeClientID     string
 	buildTimeClientSecret string
+	buildTimeProvider     string
 
 	// commandline flags
 	clientID     string
@@ -48,9 +49,30 @@ var (
 		Long: `Use a provider sub-command to authenticate against your identity provider of choice.
 For details go to: https://blog.gini.net/
 `,
+		RunE: DefaultCommand,
 	}
 )
 
+// support build time providers. If the variable buildTimeProvider is set run the provider.
+// FR: https://github.com/gini/dexter/issues/29
+func DefaultCommand(cmd *cobra.Command, args []string) error {
+	var realCommand func(cmd *cobra.Command, args []string) error
+
+	// simple approach to select the provider
+	switch buildTimeProvider {
+	case "google":
+		realCommand = GoogleCommand
+	case "azure":
+		realCommand = AzureCommand
+	default:
+		// no valid provider found: default to usage
+		return cmd.Usage()
+	}
+
+	log.Infof("Build time provider set to '%s'. Use flag --help for more options.", buildTimeProvider)
+	return realCommand(cmd, args)
+}
+
 // helper type to render the k8s config
 type CustomClaim struct {
 	Email string `json:"email"`