Add environment variable to control truncating backend.

cluster/gce/gci/configure-helper.sh

@@ -1542,6 +1542,10 @@ function start-kube-apiserver {
       if [[ -n "${ADVANCED_AUDIT_LOG_INITIAL_BACKOFF:-}" ]]; then
         params+=" --audit-log-initial-backoff=${ADVANCED_AUDIT_LOG_INITIAL_BACKOFF}"
       fi
+      # Truncating backend parameters
+      if [[ -n "${ADVANCED_AUDIT_TRUNCATING_BACKEND:-}" ]]; then
+        params+=" --audit-log-truncate-enabled=${ADVANCED_AUDIT_TRUNCATING_BACKEND}"
+      fi
     fi
     if [[ "${ADVANCED_AUDIT_BACKEND:-}" == *"webhook"* ]]; then
       params+=" --audit-webhook-mode=batch"
@@ -1575,6 +1579,10 @@ function start-kube-apiserver {
       if [[ -n "${ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF:-}" ]]; then
         params+=" --audit-webhook-initial-backoff=${ADVANCED_AUDIT_WEBHOOK_INITIAL_BACKOFF}"
       fi
+      # Truncating backend parameters
+      if [[ -n "${ADVANCED_AUDIT_TRUNCATING_BACKEND:-}" ]]; then
+        params+=" --audit-webhook-truncate-enabled=${ADVANCED_AUDIT_TRUNCATING_BACKEND}"
+      fi
     fi
   fi
 

cluster/gce/util.sh

@@ -728,6 +728,7 @@ 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_TRUNCATING_BACKEND: $(yaml-quote ${ADVANCED_AUDIT_TRUNCATING_BACKEND:-})
 ADVANCED_AUDIT_LOG_MODE: $(yaml-quote ${ADVANCED_AUDIT_LOG_MODE:-})
 ADVANCED_AUDIT_LOG_BUFFER_SIZE: $(yaml-quote ${ADVANCED_AUDIT_LOG_BUFFER_SIZE:-})
 ADVANCED_AUDIT_LOG_MAX_BATCH_SIZE: $(yaml-quote ${ADVANCED_AUDIT_LOG_MAX_BATCH_SIZE:-})