Add script to allow quickly update number of instances (#2112)

This is a fast and easy way to update number of instances for the service deployed to app engine. Works with manual-scaling types services.

release/update_num_instances.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+# Copyright 2023 The Nomulus Authors. All Rights Reserved.
+#
+# 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.
+#
+# This script updates number of instances of the service running on GCP
+# Required parameters are:
+# 1) projectId
+# 2) service name
+#
+# Example:
+# ./update_num_instances.sh domain-registry-sandbox pubapi
+set -e
+project=$1
+service=$2
+[[ -z "$1" || -z "$2" ]] && { echo "2 parameters required - projectId and service" ; exit 1; }
+echo "Project: $project";
+echo "Service: $service";
+
+deployed_version=$(gcloud app versions list --service "${service}" \
+    --project "${project}" \
+    --filter "TRAFFIC_SPLIT>0.00" \
+    --format="csv[no-heading](VERSION.ID)")
+
+service_description=$(curl -H "Authorization: Bearer $(gcloud auth print-access-token)" https://appengine.googleapis.com/v1/apps/${project}/services/${service}/versions/${deployed_version})
+echo "Service configuration: $service_description"
+
+echo "Input new number of instances: "
+
+read num_instances
+
+if [[ -n ${num_instances//[0-9]/} ]]; then
+    echo "Should be an integer"
+    exit 1;
+fi
+
+echo "Settings new number of instances: $num_instances"
+
+curl -X PATCH https://appengine.googleapis.com/v1/apps/${project}/services/${service}/versions/${deployed_version}?updateMask=manualScaling.instances \
+    -H "Authorization: Bearer $(gcloud auth print-access-token)" \
+    -H 'Content-Type: application/json' \
+    -d "{ \"manualScaling\": { \"instances\": $num_instances }}"
+
+service_description=$(curl -H "Authorization: Bearer $(gcloud auth print-access-token)" https://appengine.googleapis.com/v1/apps/${project}/services/${service}/versions/${deployed_version})
+echo "Updated service configuration: $service_description"