Example bash script to create a basic Google Compute Engine (GCE) disk backup policy (schedule snapshot) and apply the policy to GCE disks in a zone.

backup_disks.sh

#!/usr/bin/env bash
# 2020-01-02
# Create a basic GCE disk backup policy (schedule snapshot) and
# apply the policy to GCE disks in a zone.

set -e

TARGET_POLICY="backup-schedule"
ZONE="us-west1-a"
REGION="us-west1"
PROJECT="compute-impactlab"


# Creating basic backup snapshot schedule. Don't need this if schedule already exists.
gcloud compute resource-policies create snapshot-schedule $TARGET_POLICY \
    --max-retention-days 90 \
    --start-time 12:00 \
    --weekly-schedule sunday \
    --on-source-disk-delete apply-retention-policy \
    --snapshot-labels type=backup,managed-by=backup-schedule \
    --region $REGION \
    --storage-location $REGION

# Apply snapshot schedule to all disks in query.
for DISK in $(gcloud compute disks list --project compute-impactlab --filter="zone:( $ZONE )" --uri)
do
    gcloud compute disks add-resource-policies $DISK \
        --project $PROJECT \
        --zone $ZONE \
        --resource-policies=$TARGET_POLICY
done

Ug. I'm terrible about properly quoting and escaping my variables.