Merge pull request #85 from MorrisLaw/add-webhook-check-for-timeout

Add webhook check for timeouts

checks.md

@@ -371,6 +371,74 @@ webhooks:
         operator: "DoesNotExist"
 ```
 
+## Admission Controller Webhook Timeout
+
+- Name: `admission-controller-webhook-timeout`
+- Groups: `doks`
+
+Admission control webhook timeouts can block upgrades, when the API call times out, due to an incorrectly configured TimeoutSeconds value. Since webhooks inherently add to API latency, we must stay within the recommended range in order for API requests to be successful. Specifically, this happens when an admission control webhook does not respond within 30 seconds.
+
+### Example
+
+```yaml
+# Error: Configure a webhook with a TimeoutSeconds value greater than 30 seconds.
+apiVersion: admissionregistration.k8s.io/v1beta1
+kind: ValidatingWebhookConfiguration
+metadata:
+  name: sample-webhook.example.com
+webhooks:
+- name: sample-webhook.example.com
+  rules:
+  - apiGroups:
+    - ""
+    apiVersions:
+    - v1
+    operations:
+    - CREATE
+    resources:
+    - pods
+    scope: "Namespaced"
+  clientConfig:
+    service:
+      namespace: webhook
+      name: webhook-server
+      path: /pods
+  admissionReviewVersions:
+  - v1beta1
+  timeoutSeconds: 60
+```
+
+### How to Fix
+
+Set the TimeoutSeconds value to anything within the 1 to 30 second range.
+
+```yaml
+apiVersion: admissionregistration.k8s.io/v1beta1
+kind: ValidatingWebhookConfiguration
+metadata:
+  name: sample-webhook.example.com
+webhooks:
+- name: sample-webhook.example.com
+  rules:
+  - apiGroups:
+    - ""
+    apiVersions:
+    - v1
+    operations:
+    - CREATE
+    resources:
+    - pods
+    scope: "Namespaced"
+  clientConfig:
+    service:
+      namespace: webhook
+      name: webhook-server
+      path: /pods
+  admissionReviewVersions:
+  - v1beta1
+  timeoutSeconds: 10
+```
+
 ## Pod State
 
 - Name: `pod-state`

checks/doks/admission_controller_webhook_replacement.go

@@ -26,29 +26,29 @@ import (
 )
 
 func init() {
-	checks.Register(&webhookReplaementCheck{})
+	checks.Register(&webhookReplacementCheck{})
 }
 
-type webhookReplaementCheck struct{}
+type webhookReplacementCheck struct{}
 
 // Name returns a unique name for this check.
-func (w *webhookReplaementCheck) Name() string {
+func (w *webhookReplacementCheck) Name() string {
 	return "admission-controller-webhook-replacement"
 }
 
 // Groups returns a list of group names this check should be part of.
-func (w *webhookReplaementCheck) Groups() []string {
+func (w *webhookReplacementCheck) Groups() []string {
 	return []string{"doks"}
 }
 
 // Description returns a detailed human-readable description of what this check
 // does.
-func (w *webhookReplaementCheck) Description() string {
+func (w *webhookReplacementCheck) Description() string {
 	return "Check for admission control webhooks that could cause problems during upgrades or node replacement"
 }
 
 // Run runs this check on a set of Kubernetes objects.
-func (w *webhookReplaementCheck) Run(objects *kube.Objects) ([]checks.Diagnostic, error) {
+func (w *webhookReplacementCheck) Run(objects *kube.Objects) ([]checks.Diagnostic, error) {
 	const apiserverServiceName = "kubernetes"
 
 	var diagnostics []checks.Diagnostic

checks/doks/admission_controller_webhook_test.go → checks/doks/admission_controller_webhook_replacement_test.go

@@ -30,14 +30,14 @@ import (
 var webhookURL = "https://example.com/webhook"
 
 func TestWebhookCheckMeta(t *testing.T) {
-	webhookCheck := webhookReplaementCheck{}
+	webhookCheck := webhookReplacementCheck{}
 	assert.Equal(t, "admission-controller-webhook-replacement", webhookCheck.Name())
 	assert.Equal(t, []string{"doks"}, webhookCheck.Groups())
 	assert.NotEmpty(t, webhookCheck.Description())
 }
 
 func TestWebhookCheckRegistration(t *testing.T) {
-	webhookCheck := &webhookReplaementCheck{}
+	webhookCheck := &webhookReplacementCheck{}
 	check, err := checks.Get("admission-controller-webhook-replacement")
 	assert.NoError(t, err)
 	assert.Equal(t, check, webhookCheck)
@@ -236,7 +236,7 @@ func TestWebhookError(t *testing.T) {
 		},
 	}
 
-	webhookCheck := webhookReplaementCheck{}
+	webhookCheck := webhookReplacementCheck{}
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {

checks/doks/admission_controller_webhook_timeout.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2020 DigitalOcean
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package doks
+
+import (
+	"github.com/digitalocean/clusterlint/checks"
+	"github.com/digitalocean/clusterlint/kube"
+)
+
+func init() {
+	checks.Register(&webhookTimeoutCheck{})
+}
+
+type webhookTimeoutCheck struct{}
+
+// Name returns a unique name for this check.
+func (w *webhookTimeoutCheck) Name() string {
+	return "admission-controller-webhook-timeout"
+}
+
+// Groups returns a list of group names this check should be part of.
+func (w *webhookTimeoutCheck) Groups() []string {
+	return []string{"doks"}
+}
+
+// Description returns a detailed human-readable description of what this check
+// does.
+func (w *webhookTimeoutCheck) Description() string {
+	return "Check for admission control webhooks that have exceeded a timeout of 30 seconds."
+}
+
+// Run runs this check on a set of Kubernetes objects.
+func (w *webhookTimeoutCheck) Run(objects *kube.Objects) ([]checks.Diagnostic, error) {
+	var diagnostics []checks.Diagnostic
+
+	for _, config := range objects.ValidatingWebhookConfigurations.Items {
+		for _, wh := range config.Webhooks {
+			if *wh.TimeoutSeconds >= int32(1) && *wh.TimeoutSeconds < int32(30) {
+				// Webhooks with TimeoutSeconds set: between 1 and 30 is fine.
+				continue
+			}
+			d := checks.Diagnostic{
+				Severity: checks.Error,
+				Message:  "Validating webhook with a TimeoutSeconds value greater than 30 seconds will block upgrades.",
+				Kind:     checks.ValidatingWebhookConfiguration,
+				Object:   &config.ObjectMeta,
+				Owners:   config.ObjectMeta.GetOwnerReferences(),
+			}
+			diagnostics = append(diagnostics, d)
+		}
+	}
+
+	for _, config := range objects.MutatingWebhookConfigurations.Items {
+		for _, wh := range config.Webhooks {
+			if *wh.TimeoutSeconds >= int32(1) && *wh.TimeoutSeconds < int32(30) {
+				// Webhooks with TimeoutSeconds set: between 1 and 30 is fine.
+				continue
+			}
+			d := checks.Diagnostic{
+				Severity: checks.Error,
+				Message:  "Mutating webhook with a TimeoutSeconds value greater than 30 seconds will block upgrades.",
+				Kind:     checks.MutatingWebhookConfiguration,
+				Object:   &config.ObjectMeta,
+				Owners:   config.ObjectMeta.GetOwnerReferences(),
+			}
+			diagnostics = append(diagnostics, d)
+		}
+	}
+	return diagnostics, nil
+}