Make advanced audit policy on GCP configurable

cluster/common.sh

@@ -672,6 +672,7 @@ ENABLE_APISERVER_BASIC_AUDIT: $(yaml-quote ${ENABLE_APISERVER_BASIC_AUDIT:-})
 ENABLE_APISERVER_ADVANCED_AUDIT: $(yaml-quote ${ENABLE_APISERVER_ADVANCED_AUDIT:-})
 ENABLE_CACHE_MUTATION_DETECTOR: $(yaml-quote ${ENABLE_CACHE_MUTATION_DETECTOR:-false})
 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})
 GCE_API_ENDPOINT: $(yaml-quote ${GCE_API_ENDPOINT:-})
 PROMETHEUS_TO_SD_ENDPOINT: $(yaml-quote ${PROMETHEUS_TO_SD_ENDPOINT:-})

cluster/gce/gci/configure-helper.sh

@@ -480,6 +480,12 @@ EOF
 # Write the config for the audit policy.
 function create-master-audit-policy {
   local -r path="${1}"
+  local -r policy="${2:-}"
+
+  if [[ -n "${policy}" ]]; then
+    echo "${policy}" > "${path}"
+    return
+  fi
 
   # Known api groups
   local -r known_apis='
@@ -1317,7 +1323,7 @@ function start-kube-apiserver {
     local -r audit_policy_file="/etc/audit_policy.config"
     params+=" --audit-policy-file=${audit_policy_file}"
     # Create the audit policy file, and mount it into the apiserver pod.
-    create-master-audit-policy "${audit_policy_file}"
+    create-master-audit-policy "${audit_policy_file}" "${ADVANCED_AUDIT_POLICY:-}"
     audit_policy_config_mount="{\"name\": \"auditpolicyconfigmount\",\"mountPath\": \"${audit_policy_file}\", \"readOnly\": true},"
     audit_policy_config_volume="{\"name\": \"auditpolicyconfigmount\",\"hostPath\": {\"path\": \"${audit_policy_file}\", \"type\": \"FileOrCreate\"}},"