Wait for all Google App Engine operations to finish before continuing

wait_for_gae.sh

#!/bin/bash
set -x
printf "%s" "$GAE_CREDENTIALS" > ~/gaecreds.json
gcloud auth activate-service-account --key-file ~/gaecreds.json
gcloud config set project "$GCLOUD_PROJECT"

DEBIAN_FRONTEND=noninteractive
# send install logs to null for cleaner logs
apt-get install jq >/dev/null

# Define your function here
WAITFORGAE () {
    GAEJSON=$(gcloud app operations list --format=json --pending)
    PENDING_OPERATION_COUNT=$(echo "$GAEJSON" | jq '. | length')

    echo "$PENDING_OPERATION_COUNT pending operations"
    if [[ $PENDING_OPERATION_COUNT  -gt 0 ]]; then
        # tr to remove quotes
        ID=$(echo "$GAEJSON" | jq '.[0].id' | tr -d '"')=
        gcloud app operations wait "$ID"
        # Sleep up to 60 seconds to avoid multiple waiting jobs all starting at once and clobbering each other
        sleep $(( ( RANDOM % 60 )  + 1 ))
        WAITFORGAE
    fi
}

# Invoke your function
WAITFORGAE