shipperctl: add support for external auth providers

This allows it to work with, for example, GKE clusters with the 'gcp'
auth provider in ~/.kube/config.

Also tweak the quick install docs to mention that you need to be a real
cluster-admin. On GKE you need to create a clusterrolebinding first;
otherwise you see errors that indicate trying to create the new Shipper
clusterroles is privilege escalation.

This commit includes a giant pile of new stuff in vendor: this is
everything all of the cloud providers for their auth plugins.

Gopkg.toml

@@ -37,6 +37,10 @@ required = ["k8s.io/code-generator/cmd/client-gen"]
   name = "github.com/spf13/pflag"
   version = "1.0.3"
 
+[[override]]
+  name = "github.com/Azure/go-autorest"
+  revision = "e14a70c556c8e0db173358d1a903dca345a8e75e"
+
 [[constraint]]
   version = "kubernetes-1.11.4"
   name = "k8s.io/apiextensions-apiserver"

cmd/shipperctl/configurator/cluster.go

@@ -12,6 +12,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
+	_ "k8s.io/client-go/plugin/pkg/client/auth"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 

docs/start/install.rst

@@ -12,7 +12,8 @@ The rest of this document assumes that you have access to a Kubernetes cluster
 and admin privileges on it. If you don't have this, check out `microk8s
 <https://microk8s.io/>`_ or `minikube
 <https://github.com/kubernetes/minikube>`_. Cloud clusters like GKE are also
-fine. Shipper requires Kubernetes 1.11 or later.
+fine. Shipper requires Kubernetes 1.11 or later, and you'll need to be an admin
+on the cluster you're working with. [#f1]_
 
 Make sure that ``kubectl`` works and can connect to your cluster before
 continuing.
@@ -104,3 +105,7 @@ Step 5: do a rollout!
 *********************
 
 Now we should have a working Shipper installation. :ref:`Let's roll something out! <user_rolling-out>`
+
+.. rubric:: Footnotes
+
+.. [#f1] For example, on GKE you need to `bind yourself to cluster-admin <https://stackoverflow.com/a/52972588>`_ before ``shipperctl`` will work.