feat: Resolving API groups (#40)

* test: Add integration test scenario for resolving API group

* feat: Resolve resource API groups

Kubernetes assigns resources to API grups. So you can have pods
in the core group as well as pods in the metrics.k8s.io groups.
With the changes introduced the plugin allows you to specify the
fully qualified resoruce name at the command line, for example:

$ kubect who-can get pods
$ kubect who-can get pods.metrics.k8s.io

Resolves: #35, #38

README.md

@@ -6,9 +6,9 @@
 
 # kubectl-who-can
 
-Shows who has permissions to VERB [TYPE | TYPE/NAME | NONRESOURCEURL] in Kubernetes.
+Shows which subjects have RBAC permissions to VERB [TYPE | TYPE/NAME | NONRESOURCEURL] in Kubernetes.
 
-[![asciicast](https://asciinema.org/a/ccqqYwA5L5rMV9kd1tgzyZJ2j.svg)](https://asciinema.org/a/ccqqYwA5L5rMV9kd1tgzyZJ2j)
+[![asciicast][asciicast-img]][asciicast]
 
 ## Installation
 
@@ -31,7 +31,7 @@ Download a release distribution archive for your operating system, extract it, a
 executable to your `$PATH`. For example, to manually install `kubectl-who-can` on macOS run the following command:
 
 ```
-VERSION="v0.1.0-alpha.1"
+VERSION=`git describe --abbrev=0`
 
 mkdir -p /tmp/who-can/$VERSION && \
 curl -L https://github.com/aquasecurity/kubectl-who-can/releases/download/$VERSION/kubectl-who-can_darwin_x86_64.tar.gz \
@@ -83,3 +83,6 @@ The `kubectl-who-can` binary will be in `/usr/local/bin`.
 
 [license-img]: https://img.shields.io/github/license/aquasecurity/kubectl-who-can.svg
 [license]: https://github.com/aquasecurity/kubectl-who-can/blob/master/LICENSE
+
+[asciicast-img]: https://asciinema.org/a/ccqqYwA5L5rMV9kd1tgzyZJ2j.svg
+[asciicast]: https://asciinema.org/a/ccqqYwA5L5rMV9kd1tgzyZJ2j

go.mod

@@ -4,11 +4,11 @@ go 1.12
 
 require (
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
-	github.com/spf13/cobra v0.0.0-20180319062004-c439c4fa0937
-	github.com/stretchr/objx v0.2.0 // indirect
+	github.com/spf13/cobra v0.0.4
 	github.com/stretchr/testify v1.3.0
-	k8s.io/api v0.0.0-20190612125737-db0771252981
-	k8s.io/apimachinery v0.0.0-20190612125636-6a5db36e93ad
+	k8s.io/api v0.0.0-20190703205437-39734b2a72fe
+	k8s.io/apiextensions-apiserver v0.0.0-20190704050600-357b4270afe4
+	k8s.io/apimachinery v0.0.0-20190703205208-4cfb76a8bf76
 	k8s.io/cli-runtime v0.0.0-20190612131021-ced92c4c4749
-	k8s.io/client-go v0.0.0-20190612125919-5c45477a8ae7
+	k8s.io/client-go v0.0.0-20190704045512-07281898b0f0
 )

pkg/cmd/access_checker.go

@@ -17,6 +17,7 @@ type accessChecker struct {
 	client clientauthz.SelfSubjectAccessReviewInterface
 }
 
+// NewAccessChecker constructs the default AccessChecker.
 func NewAccessChecker(client clientauthz.SelfSubjectAccessReviewInterface) AccessChecker {
 	return &accessChecker{
 		client: client,

pkg/cmd/list.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"github.com/spf13/cobra"
 	core "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	clioptions "k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/client-go/kubernetes"
 	clientcore "k8s.io/client-go/kubernetes/typed/core/v1"
@@ -24,14 +25,18 @@ const (
 	whoCanLong  = `Shows which users, groups and service accounts can perform a given verb on a given resource type.
 
 VERB is a logical Kubernetes API verb like 'get', 'list', 'watch', 'delete', etc.
-TYPE is a Kubernetes resource. Shortcuts, such as 'pod' or 'po' will be resolved. NAME is the name of a particular Kubernetes resource.
+TYPE is a Kubernetes resource. Shortcuts and API groups will be resolved, e.g. 'po' or 'pods.metrics.k8s.io'.
+NAME is the name of a particular Kubernetes resource.
 NONRESOURCEURL is a partial URL that starts with "/".`
 	whoCanExample = `  # List who can get pods in any namespace
   kubectl who-can get pods --all-namespaces
 
   # List who can create pods in the current namespace
   kubectl who-can create pods
 
+  # List who can get pods specifying the API group
+  kubectl who-can get pods.metrics.k8s.io
+
   # List who can create services in namespace "foo"
   kubectl who-can create services -n foo
 
@@ -63,6 +68,7 @@ type Action struct {
 	nonResourceURL string
 	subResource    string
 	resourceName   string
+	gr            schema.GroupResource
 
 	namespace     string
 	allNamespaces bool
@@ -186,7 +192,7 @@ func (w *whoCan) Complete(args []string) error {
 	}
 
 	if w.resource != "" {
-		w.resource, err = w.resourceResolver.Resolve(w.verb, w.resource, w.subResource)
+		w.gr, err = w.resourceResolver.Resolve(w.verb, w.resource, w.subResource)
 		if err != nil {
 			return fmt.Errorf("resolving resource: %v", err)
 		}

pkg/cmd/list_test.go

@@ -9,6 +9,7 @@ import (
 	core "k8s.io/api/core/v1"
 	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	clioptions "k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/client-go/kubernetes/fake"
 	clientTesting "k8s.io/client-go/testing"
@@ -40,9 +41,9 @@ type resourceResolverMock struct {
 	mock.Mock
 }
 
-func (r *resourceResolverMock) Resolve(verb, resource, subResource string) (string, error) {
+func (r *resourceResolverMock) Resolve(verb, resource, subResource string) (schema.GroupResource, error) {
 	args := r.Called(verb, resource, subResource)
-	return args.String(0), args.Error(1)
+	return args.Get(0).(schema.GroupResource), args.Error(1)
 }
 
 type clientConfigMock struct {
@@ -91,8 +92,8 @@ func TestComplete(t *testing.T) {
 		resource    string
 		subResource string
 
-		result string
-		err    error
+		gr  schema.GroupResource
+		err error
 	}
 
 	type expected struct {
@@ -106,20 +107,20 @@ func TestComplete(t *testing.T) {
 	data := []struct {
 		scenario string
 
-		*currentContext
+		currentContext *currentContext
 
-		flags flags
-		args  []string
-		*resolution
+		flags      flags
+		args       []string
+		resolution *resolution
 
-		expected
+		expected expected
 	}{
 		{
 			scenario:       "A",
 			currentContext: &currentContext{namespace: "foo"},
 			flags:          flags{namespace: "", allNamespaces: false},
 			args:           []string{"list", "pods"},
-			resolution:     &resolution{verb: "list", resource: "pods", result: "pods"},
+			resolution:     &resolution{verb: "list", resource: "pods", gr: schema.GroupResource{Resource: "pods"}},
 			expected: expected{
 				namespace:    "foo",
 				verb:         "list",
@@ -132,7 +133,7 @@ func TestComplete(t *testing.T) {
 			currentContext: &currentContext{err: errors.New("cannot open context")},
 			flags:          flags{namespace: "", allNamespaces: false},
 			args:           []string{"list", "pods"},
-			resolution:     &resolution{verb: "list", resource: "pods", result: "pods"},
+			resolution:     &resolution{verb: "list", resource: "pods", gr: schema.GroupResource{Resource: "pods"}},
 			expected: expected{
 				namespace:    "",
 				verb:         "list",
@@ -145,7 +146,7 @@ func TestComplete(t *testing.T) {
 			scenario:   "C",
 			flags:      flags{namespace: "", allNamespaces: true},
 			args:       []string{"get", "service/mongodb"},
-			resolution: &resolution{verb: "get", resource: "service", result: "services"},
+			resolution: &resolution{verb: "get", resource: "service", gr: schema.GroupResource{Resource: "services"}},
 			expected: expected{
 				namespace:    core.NamespaceAll,
 				verb:         "get",
@@ -157,7 +158,7 @@ func TestComplete(t *testing.T) {
 			scenario:   "D",
 			flags:      flags{namespace: "bar", allNamespaces: false},
 			args:       []string{"delete", "pv"},
-			resolution: &resolution{verb: "delete", resource: "pv", result: "persistentvolumes"},
+			resolution: &resolution{verb: "delete", resource: "pv", gr: schema.GroupResource{Resource: "persistentvolumes"}},
 			expected: expected{
 				namespace: "bar",
 				verb:      "delete",
@@ -211,7 +212,7 @@ func TestComplete(t *testing.T) {
 
 			if tt.resolution != nil {
 				resourceResolver.On("Resolve", tt.resolution.verb, tt.resolution.resource, tt.resolution.subResource).
-					Return(tt.resolution.result, tt.resolution.err)
+					Return(tt.resolution.gr, tt.resolution.err)
 			}
 			if tt.currentContext != nil {
 				clientConfig.On("Namespace").Return(tt.currentContext.namespace, false, tt.currentContext.err)
@@ -239,7 +240,7 @@ func TestComplete(t *testing.T) {
 			assert.Equal(t, tt.expected.err, err)
 			assert.Equal(t, tt.expected.namespace, o.namespace)
 			assert.Equal(t, tt.expected.verb, o.verb)
-			assert.Equal(t, tt.expected.resource, o.resource)
+			assert.Equal(t, tt.expected.resource, o.gr.Resource)
 			assert.Equal(t, tt.expected.resourceName, o.resourceName)
 
 			clientConfig.AssertExpectations(t)

pkg/cmd/namespace_validator.go

@@ -8,6 +8,10 @@ import (
 	clientcore "k8s.io/client-go/kubernetes/typed/core/v1"
 )
 
+// NamespaceValidator wraps the Validate method.
+//
+// Validate checks whether the given namespace exists or not.
+// Returns nil if it exists, an error otherwise.
 type NamespaceValidator interface {
 	Validate(name string) error
 }
@@ -16,6 +20,7 @@ type namespaceValidator struct {
 	client clientcore.NamespaceInterface
 }
 
+// NewNamespaceValidator constructs the default NamespaceValidator.
 func NewNamespaceValidator(client clientcore.NamespaceInterface) NamespaceValidator {
 	return &namespaceValidator{
 		client: client,

pkg/cmd/policy_rule_matcher.go

@@ -8,7 +8,8 @@ import (
 // PolicyRuleMatcher wraps the Matches* methods.
 //
 // MatchesRole returns `true` if any PolicyRule defined by the given Role matches the specified Action, `false` otherwise.
-// MatchesClusterRole returns `true` if any PolicyRule defined by the given ClusterRole matches the specified  Action, `false` otherwise.
+//
+// MatchesClusterRole returns `true` if any PolicyRule defined by the given ClusterRole matches the specified Action, `false` otherwise.
 type PolicyRuleMatcher interface {
 	MatchesRole(role rbac.Role, action Action) bool
 	MatchesClusterRole(role rbac.ClusterRole, action Action) bool
@@ -17,7 +18,7 @@ type PolicyRuleMatcher interface {
 type matcher struct {
 }
 
-// NewPolicyRuleMatcher constructs a PolicyRuleMatcher.
+// NewPolicyRuleMatcher constructs the default PolicyRuleMatcher.
 func NewPolicyRuleMatcher() PolicyRuleMatcher {
 	return &matcher{}
 }
@@ -54,11 +55,26 @@ func (m *matcher) matches(rule rbac.PolicyRule, action Action) bool {
 			m.matchesNonResourceURL(rule, action.nonResourceURL)
 	}
 
+	resource := action.gr.Resource
+	if action.subResource != "" {
+		resource += "/" + action.subResource
+	}
+
 	return m.matchesVerb(rule, action.verb) &&
-		m.matchesResource(rule, action.resource) &&
+		m.matchesResource(rule, resource) &&
+		m.matchesAPIGroup(rule, action.gr.Group) &&
 		m.matchesResourceName(rule, action.resourceName)
 }
 
+func (m *matcher) matchesAPIGroup(rule rbac.PolicyRule, actionGroup string) bool {
+	for _, group := range rule.APIGroups {
+		if group == rbac.APIGroupAll || group == actionGroup {
+			return true
+		}
+	}
+	return false
+}
+
 func (m *matcher) matchesVerb(rule rbac.PolicyRule, actionVerb string) bool {
 	for _, verb := range rule.Verbs {
 		if verb == rbac.VerbAll || verb == actionVerb {