e2e: allow unknown providers with a warning

test/e2e/framework/BUILD

@@ -134,6 +134,7 @@ go_library(
         "//vendor/github.com/onsi/ginkgo/config:go_default_library",
         "//vendor/github.com/onsi/gomega:go_default_library",
         "//vendor/github.com/onsi/gomega/types:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
         "//vendor/github.com/prometheus/common/expfmt:go_default_library",
         "//vendor/github.com/prometheus/common/model:go_default_library",
         "//vendor/golang.org/x/crypto/ssh:go_default_library",

test/e2e/framework/provider.go

@@ -18,8 +18,11 @@ package framework
 
 import (
 	"fmt"
+	"os"
 	"sync"
 
+	"github.com/pkg/errors"
+
 	"k8s.io/api/core/v1"
 	clientset "k8s.io/client-go/kubernetes"
 )
@@ -66,7 +69,7 @@ func SetupProviderConfig(providerName string) (ProviderInterface, error) {
 	defer mutex.Unlock()
 	factory, ok := providers[providerName]
 	if !ok {
-		return nil, fmt.Errorf("The provider %s is unknown.", providerName)
+		return nil, errors.Wrapf(os.ErrNotExist, "The provider %s is unknown.", providerName)
 	}
 	provider, err := factory()
 

test/e2e/framework/test_context.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/onsi/ginkgo/config"
+	"github.com/pkg/errors"
 	utilflag "k8s.io/apiserver/pkg/util/flag"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -366,7 +367,20 @@ func AfterReadingAllFlags(t *TestContextType) {
 	// Make sure that all test runs have a valid TestContext.CloudConfig.Provider.
 	var err error
 	TestContext.CloudConfig.Provider, err = SetupProviderConfig(TestContext.Provider)
+	if err == nil {
+		return
+	}
+	if !os.IsNotExist(errors.Cause(err)) {
+		Failf("Failed to setup provider config: %v", err)
+	}
+	// We allow unknown provider parameters for historic reasons. At least log a
+	// warning to catch typos.
+	// TODO (https://github.com/kubernetes/kubernetes/issues/70200):
+	// - remove the fallback for unknown providers
+	// - proper error message instead of Failf (which panics)
+	glog.Warningf("Unknown provider %q, proceeding as for --provider=skeleton.", TestContext.Provider)
+	TestContext.CloudConfig.Provider, err = SetupProviderConfig("skeleton")
 	if err != nil {
-		Failf("Failed to setup provide r config: %v", err)
+		Failf("Failed to setup fallback skeleton provider config: %v", err)
 	}
 }