From e09a1221bb793618bed59632b22f12e9fdc31dd9 Mon Sep 17 00:00:00 2001
From: Thomas Stromberg <tstromberg@google.com>
Date: Thu, 2 Apr 2020 06:20:35 -0700
Subject: [PATCH] Add rejection reason to 'unable to find driver' error

---
 cmd/minikube/cmd/start.go       | 10 ++++++++--
 pkg/minikube/driver/driver.go   | 21 +++++++++++++++++----
 pkg/minikube/out/style.go       |  1 +
 pkg/minikube/out/style_enum.go  |  1 +
 pkg/minikube/registry/global.go |  2 ++
 5 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/cmd/minikube/cmd/start.go b/cmd/minikube/cmd/start.go
index 56326fa41f..7bbe224ec6 100644
--- a/cmd/minikube/cmd/start.go
+++ b/cmd/minikube/cmd/start.go
@@ -561,9 +561,15 @@ func selectDriver(existing *config.ClusterConfig) registry.DriverState {
 		return ds
 	}
 
-	pick, alts := driver.Suggest(driver.Choices(viper.GetBool("vm")))
+	choices := driver.Choices(viper.GetBool("vm"))
+	pick, alts, rejects := driver.Suggest(choices)
 	if pick.Name == "" {
-		exit.WithCodeT(exit.Config, "Unable to determine a default driver to use. Try specifying --driver, or see https://minikube.sigs.k8s.io/docs/start/")
+		out.T(out.ThumbsDown, "Unable to pick a default driver. Here is what was considered, in preference order:")
+		for _, r := range rejects {
+			out.T(out.Option, "{{ .name }}: {{ .rejection }}", out.V{"name": r.Name, "rejection": r.Rejection})
+		}
+		out.T(out.Workaround, "Try specifying a --driver, or see https://minikube.sigs.k8s.io/docs/start/")
+		os.Exit(exit.Unavailable)
 	}
 
 	if len(alts) > 1 {
diff --git a/pkg/minikube/driver/driver.go b/pkg/minikube/driver/driver.go
index ed0cbdee23..bc2ca06c0a 100644
--- a/pkg/minikube/driver/driver.go
+++ b/pkg/minikube/driver/driver.go
@@ -174,8 +174,8 @@ func Choices(vm bool) []registry.DriverState {
 	return options
 }
 
-// Suggest returns a suggested driver from a set of options
-func Suggest(options []registry.DriverState) (registry.DriverState, []registry.DriverState) {
+// Suggest returns a suggested driver, alternate drivers, and rejected drivers
+func Suggest(options []registry.DriverState) (registry.DriverState, []registry.DriverState, []registry.DriverState) {
 	pick := registry.DriverState{}
 	for _, ds := range options {
 		if !ds.State.Installed {
@@ -198,17 +198,30 @@ func Suggest(options []registry.DriverState) (registry.DriverState, []registry.D
 	}
 
 	alternates := []registry.DriverState{}
+	rejects := []registry.DriverState{}
 	for _, ds := range options {
 		if ds != pick {
-			if !ds.State.Healthy || !ds.State.Installed {
+			glog.Errorf("%s: %s", ds.Name, ds.Rejection)
+			if !ds.State.Healthy {
+				ds.Rejection = fmt.Sprintf("Not healthy: %v", ds.State.Error)
+				rejects = append(rejects, ds)
 				continue
 			}
+
+			if !ds.State.Installed {
+				ds.Rejection = fmt.Sprintf("Not installed: %v", ds.State.Error)
+				rejects = append(rejects, ds)
+				continue
+			}
+
+			ds.Rejection = fmt.Sprintf("%s is preferred", pick.Name)
 			alternates = append(alternates, ds)
 		}
 	}
 	glog.Infof("Picked: %+v", pick)
 	glog.Infof("Alternatives: %+v", alternates)
-	return pick, alternates
+	glog.Infof("Rejects: %+v", rejects)
+	return pick, alternates, rejects
 }
 
 // Status returns the status of a driver
diff --git a/pkg/minikube/out/style.go b/pkg/minikube/out/style.go
index c67188e12d..a8eee7811e 100644
--- a/pkg/minikube/out/style.go
+++ b/pkg/minikube/out/style.go
@@ -68,6 +68,7 @@ var styles = map[StyleEnum]style{
 	Launch:        {Prefix: "🚀  "},
 	Sad:           {Prefix: "😿  "},
 	ThumbsUp:      {Prefix: "👍  "},
+	ThumbsDown:    {Prefix: "👎  "},
 	Option:        {Prefix: "    ▪ ", LowPrefix: lowIndent}, // Indented bullet
 	Command:       {Prefix: "    ▪ ", LowPrefix: lowIndent}, // Indented bullet
 	LogEntry:      {Prefix: "    "},                         // Indent
diff --git a/pkg/minikube/out/style_enum.go b/pkg/minikube/out/style_enum.go
index 097f4452dc..1437b26823 100644
--- a/pkg/minikube/out/style_enum.go
+++ b/pkg/minikube/out/style_enum.go
@@ -41,6 +41,7 @@ const (
 	Launch
 	Sad
 	ThumbsUp
+	ThumbsDown
 	Option
 	Command
 	LogEntry
diff --git a/pkg/minikube/registry/global.go b/pkg/minikube/registry/global.go
index 16ede79a27..3f608ef471 100644
--- a/pkg/minikube/registry/global.go
+++ b/pkg/minikube/registry/global.go
@@ -68,6 +68,8 @@ type DriverState struct {
 	Name     string
 	Priority Priority
 	State    State
+	// Rejection is why we chose not to use this driver
+	Rejection string
 }
 
 func (d DriverState) String() string {