Make audit webhook backend configurable in startup scripts

cluster/common.sh

@@ -664,6 +664,12 @@ ENABLE_CACHE_MUTATION_DETECTOR: $(yaml-quote ${ENABLE_CACHE_MUTATION_DETECTOR:-f
 ENABLE_PATCH_CONVERSION_DETECTOR: $(yaml-quote ${ENABLE_PATCH_CONVERSION_DETECTOR:-false})
 ADVANCED_AUDIT_POLICY: $(yaml-quote ${ADVANCED_AUDIT_POLICY:-})
 ADVANCED_AUDIT_BACKEND: $(yaml-quote ${ADVANCED_AUDIT_BACKEND:-log})
+ADVANCED_AUDIT_WEBHOOK_BUFFER_SIZE: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_BUFFER_SIZE:-})
+ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_SIZE: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_SIZE:-})
+ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_WAIT: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_WAIT:-})
+ADVANCED_AUDIT_WEBHOOK_THROTTLE_QPS: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_THROTTLE_QPS:-})
+ADVANCED_AUDIT_WEBHOOK_THROTTLE_BURST: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_THROTTLE_BURST:-})
+ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF: $(yaml-quote ${ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF:-})
 GCE_API_ENDPOINT: $(yaml-quote ${GCE_API_ENDPOINT:-})
 PROMETHEUS_TO_SD_ENDPOINT: $(yaml-quote ${PROMETHEUS_TO_SD_ENDPOINT:-})
 PROMETHEUS_TO_SD_PREFIX: $(yaml-quote ${PROMETHEUS_TO_SD_PREFIX:-})

cluster/gce/gci/configure-helper.sh

@@ -1612,6 +1612,24 @@ function start-kube-apiserver {
       # Create the audit webhook config file, and mount it into the apiserver pod.
       local -r audit_webhook_config_file="/etc/audit_webhook.config"
       params+=" --audit-webhook-config-file=${audit_webhook_config_file}"
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_BUFFER_SIZE:-}" ]]; then
+        params+=" --audit-webhook-batch-buffer-size=${ADVANCED_AUDIT_WEBHOOK_BUFFER_SIZE}"
+      fi
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_SIZE:-}" ]]; then
+        params+=" --audit-webhook-batch-max-size=${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_SIZE}"
+      fi
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_WAIT:-}" ]]; then
+        params+=" --audit-webhook-batch-max-wait=${ADVANCED_AUDIT_WEBHOOK_MAX_BATCH_WAIT}"
+      fi
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_THROTTLE_QPS:-}" ]]; then
+        params+=" --audit-webhook-batch-throttle-qps=${ADVANCED_AUDIT_WEBHOOK_THROTTLE_QPS}"
+      fi
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_THROTTLE_BURST:-}" ]]; then
+        params+=" --audit-webhook-batch-throttle-burst=${ADVANCED_AUDIT_WEBHOOK_THROTTLE_BURST}"
+      fi
+      if [[ -n "${ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF:-}" ]]; then
+        params+=" --audit-webhook-batch-initial-backoff=${ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF}"
+      fi
       create-master-audit-webhook-config "${audit_webhook_config_file}"
       audit_webhook_config_mount="{\"name\": \"auditwebhookconfigmount\",\"mountPath\": \"${audit_webhook_config_file}\", \"readOnly\": true},"
       audit_webhook_config_volume="{\"name\": \"auditwebhookconfigmount\",\"hostPath\": {\"path\": \"${audit_webhook_config_file}\", \"type\": \"FileOrCreate\"}},"