Add leader-election config

config/200-clusterrole.yaml

@@ -24,6 +24,9 @@ rules:
   - apiGroups: ["apps"]
     resources: ["deployments", "deployments/finalizers"] # finalizers are needed for the owner reference of the webhook
     verbs: ["get", "list", "create", "update", "delete", "patch", "watch"]
+  - apiGroups: ["coordination.k8s.io"]
+    resources: ["leases"]
+    verbs: ["get", "list", "create", "update", "delete", "patch", "watch"]
   - apiGroups: ["admissionregistration.k8s.io"]
     resources: ["mutatingwebhookconfigurations", "validatingwebhookconfigurations"]
     verbs: ["get", "list", "create", "update", "delete", "patch", "watch"]

config/config-leader-election.yaml

@@ -0,0 +1,48 @@
+# Copyright 2020 The Knative Authors
+#
+# 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
+#
+#     https://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.
+
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: config-leader-election
+  namespace: knative-samples
+  labels:
+    samples.knative.dev/release: devel
+data:
+  _example: |
+    ################################
+    #                              #
+    #    EXAMPLE CONFIGURATION     #
+    #                              #
+    ################################
+    # This block is not actually functional configuration,
+    # but serves to illustrate the available configuration
+    # options and document them in a way that is accessible
+    # to users that `kubectl edit` this config map.
+    #
+    # These sample configuration options may be copied out of
+    # this example block and unindented to be in the data block
+    # to actually change the configuration.
+    # leaseDuration is how long non-leaders will wait to try to acquire the
+    # lock; 15 seconds is the value used by core kubernetes controllers.
+    leaseDuration: "15s"
+    # renewDeadline is how long a leader will try to renew the lease before
+    # giving up; 10 seconds is the value used by core kubernetes controllers.
+    renewDeadline: "10s"
+    # retryPeriod is how long the leader election client waits between tries of
+    # actions; 2 seconds is the value used by core kubernetes controllers.
+    retryPeriod: "2s"
+    # enabledComponents is a comma-delimited list of component names for which
+    # leader election is enabled. Valid values are:
+    enabledComponents: "controller,webhook"