From baa0bf739cdd4a599e40170a75ca718d7c70612f Mon Sep 17 00:00:00 2001
From: Varsha Varadarajan <vvaradarajan@digitalocean.com>
Date: Fri, 14 Jun 2019 15:22:17 -0400
Subject: [PATCH] Add node name check: Checks for pods which use node name in
 the node selector.

---
 checks/all/all.go                          |  1 +
 checks/doks/node_name_pod_selector.go      | 45 ++++++++++++++
 checks/doks/node_name_pod_selector_test.go | 71 ++++++++++++++++++++++
 3 files changed, 117 insertions(+)
 create mode 100644 checks/doks/node_name_pod_selector.go
 create mode 100644 checks/doks/node_name_pod_selector_test.go

diff --git a/checks/all/all.go b/checks/all/all.go
index 0821e8f..e835ee8 100644
--- a/checks/all/all.go
+++ b/checks/all/all.go
@@ -4,5 +4,6 @@ package all
 
 import (
 	_ "github.com/digitalocean/clusterlint/checks/basic"
+	_ "github.com/digitalocean/clusterlint/checks/doks"
 	_ "github.com/digitalocean/clusterlint/checks/noop"
 )
diff --git a/checks/doks/node_name_pod_selector.go b/checks/doks/node_name_pod_selector.go
new file mode 100644
index 0000000..090969e
--- /dev/null
+++ b/checks/doks/node_name_pod_selector.go
@@ -0,0 +1,45 @@
+package doks
+
+import (
+	"fmt"
+
+	"github.com/digitalocean/clusterlint/checks"
+	"github.com/digitalocean/clusterlint/kube"
+	corev1 "k8s.io/api/core/v1"
+)
+
+func init() {
+	checks.Register(&podSelectorCheck{})
+}
+
+type podSelectorCheck struct{}
+
+// Name returns a unique name for this check.
+func (nc *podSelectorCheck) Name() string {
+	return "node-name-pod-selector"
+}
+
+// Groups returns a list of group names this check should be part of.
+func (nc *podSelectorCheck) Groups() []string {
+	return []string{"doks"}
+}
+
+// Description returns a detailed human-readable description of what this check
+// does.
+func (nc *podSelectorCheck) Description() string {
+	return "Checks if there are pods which use kubernetes.io/hostname label in the node selector."
+}
+
+// Run runs this check on a set of Kubernetes objects. It can return warnings
+// (low-priority problems) and errors (high-priority problems) as well as an
+// error value indicating that the check failed to run.
+func (nc *podSelectorCheck) Run(objects *kube.Objects) (warnings []error, errors []error, err error) {
+	var e []error
+	for _, pod := range objects.Pods.Items {
+		nodeSelectorMap := pod.Spec.NodeSelector
+		if _, ok := nodeSelectorMap[corev1.LabelHostname]; ok {
+			e = append(e, fmt.Errorf("pod '%s' in namespace '%s' uses the node name for node selector", pod.GetName(), pod.GetNamespace()))
+		}
+	}
+	return nil, e, nil
+}
diff --git a/checks/doks/node_name_pod_selector_test.go b/checks/doks/node_name_pod_selector_test.go
new file mode 100644
index 0000000..61ab94d
--- /dev/null
+++ b/checks/doks/node_name_pod_selector_test.go
@@ -0,0 +1,71 @@
+package doks
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/digitalocean/clusterlint/kube"
+	"github.com/stretchr/testify/assert"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestGroup(t *testing.T) {
+	podSelectorCheck := podSelectorCheck{}
+	assert.Equal(t, []string{"doks"}, podSelectorCheck.Groups())
+}
+
+func TestNodeNameError(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		arg      *kube.Objects
+		expected []error
+	}{
+		{
+			name:     "no node name selector",
+			arg:      empty(),
+			expected: nil,
+		},
+		{
+			name:     "node name used in node selector",
+			arg:      invalidPod(),
+			expected: errors(),
+		},
+	}
+
+	podSelectorCheck := podSelectorCheck{}
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			_, e, _ := podSelectorCheck.Run(scenario.arg)
+			assert.ElementsMatch(t, scenario.expected, e)
+		})
+	}
+}
+
+func empty() *kube.Objects {
+	objs := &kube.Objects{
+		Pods: &corev1.PodList{},
+	}
+	return objs
+}
+
+func invalidPod() *kube.Objects {
+	objs := empty()
+	objs.Pods = &corev1.PodList{
+		Items: []corev1.Pod{
+			{
+				ObjectMeta: metav1.ObjectMeta{Name: "pod_foo", Namespace: "k8s"},
+				Spec:       corev1.PodSpec{NodeSelector: map[string]string{corev1.LabelHostname: "foo"}},
+			},
+		},
+	}
+	return objs
+}
+
+func errors() []error {
+	e := []error{
+		fmt.Errorf("pod 'pod_foo' in namespace 'k8s' uses the node name for node selector"),
+	}
+	return e
+}