name: Delete GCP resources

on:
  # Run daily, when most devs aren't working
  # 0700 UTC is after AEST working hours but before ET working hours
  schedule:
    - cron: "0 7 * * *"
  workflow_dispatch:

env:
  # Delete all resources created before $DELETE_INSTANCE_DAYS days ago.
  # We keep this short to reduce CPU, RAM, and storage costs.
  DELETE_INSTANCE_DAYS: 3
  # Delete all other resources created before $DELETE_AGE_DAYS days ago.
  # We keep this short to reduce storage costs.
  DELETE_AGE_DAYS: 2
  # But keep the latest $KEEP_LATEST_IMAGE_COUNT images of each type.
  # We keep this small to reduce storage costs.
  KEEP_LATEST_IMAGE_COUNT: 2

jobs:
  delete-resources:
    name: Delete old GCP resources
    runs-on: ubuntu-latest
    permissions:
      contents: 'read'
      id-token: 'write'
    steps:
      - uses: actions/checkout@v3.2.0
        with:
          persist-credentials: false

      # Setup gcloud CLI
      - name: Authenticate to Google Cloud
        id: auth
        uses: google-github-actions/auth@v1.0.0
        with:
          retries: '3'
          workload_identity_provider: 'projects/143793276228/locations/global/workloadIdentityPools/github-actions/providers/github-oidc'
          service_account: 'github-service-account@zealous-zebra.iam.gserviceaccount.com'

      - name: Set up Cloud SDK
        uses: google-github-actions/setup-gcloud@v1.0.1

      # Deletes all instances older than $DELETE_INSTANCE_DAYS days.
      #
      # We only delete instances that end in 7 or more hex characters,
      # to avoid deleting managed instance groups and manually created instances.
      #
      # ${INSTANCE_AND_ZONE} expands to:
      # <instance-name> --zone=<zone-name>
      # so it can't be shell-quoted.
      - name: Delete old instances
        run: |
          DELETE_BEFORE_DATE=$(date --date="$DELETE_INSTANCE_DAYS days ago" '+%Y%m%d')

          IFS=$'\n'
          INSTANCES=$(gcloud compute instances list --sort-by=creationTimestamp --filter="name~-[0-9a-f]{7,}$ AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME,ZONE)' | \
                      sed 's/\(.*\)\t\(.*\)/\1 --zone=\2/')

          for INSTANCE_AND_ZONE in $INSTANCES
          do
            IFS=$' '
            gcloud compute instances delete --verbosity=info ${INSTANCE_AND_ZONE} --delete-disks=all || continue
            IFS=$'\n'
          done

      # Deletes all the instance templates older than $DELETE_AGE_DAYS days.
      - name: Delete old instance templates
        run: |
          DELETE_BEFORE_DATE=$(date --date="$DELETE_AGE_DAYS days ago" '+%Y%m%d')
          TEMPLATES=$(gcloud compute instance-templates list --sort-by=creationTimestamp --filter="name~-[0-9a-f]{7,}$ AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME)')

          for TEMPLATE in $TEMPLATES
          do
            gcloud compute instance-templates delete "${TEMPLATE}" || continue
          done

      # Deletes all the disks older than $DELETE_AGE_DAYS days.
      #
      # Disks that are attached to an instance template can't be deleted, so it is safe to try to delete all disks here.
      #
      # ${DISK_AND_LOCATION} expands to:
      # <disk-name> --[zone|region]=<location-name>
      # so it can't be shell-quoted.
      - name: Delete old disks
        run: |
          DELETE_BEFORE_DATE=$(date --date="$DELETE_AGE_DAYS days ago" '+%Y%m%d')

          IFS=$'\n'
          # Disks created by PR jobs, and other jobs that use a commit hash
          COMMIT_DISKS=$(gcloud compute disks list --sort-by=creationTimestamp --filter="name~-[0-9a-f]{7,}$ AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME,LOCATION,LOCATION_SCOPE)' | \
                         sed 's/\(.*\)\t\(.*\)\t\(.*\)/\1 --\3=\2/')

          for DISK_AND_LOCATION in $COMMIT_DISKS
          do
            IFS=$' '
            gcloud compute disks delete --verbosity=info ${DISK_AND_LOCATION} || continue
            IFS=$'\n'
          done
          
          IFS=$'\n'
          # Disks created by managed instance groups, and other jobs that start with "zebrad-"
          ZEBRAD_DISKS=$(gcloud compute disks list --sort-by=creationTimestamp --filter="name~^zebrad- AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME,LOCATION,LOCATION_SCOPE)' | \
                         sed 's/\(.*\)\t\(.*\)\t\(.*\)/\1 --\3=\2/')

          for DISK_AND_LOCATION in $ZEBRAD_DISKS
          do
            IFS=$' '
            gcloud compute disks delete --verbosity=info ${DISK_AND_LOCATION} || continue
            IFS=$'\n'
          done

      # Deletes cache images older than $DELETE_AGE_DAYS days.
      #
      # Keeps all images younger than $DELETE_AGE_DAYS.
      # Also keeps $KEEP_LATEST_IMAGE_COUNT older images of each type:
      # - zebrad checkpoint cache
      # - zebrad tip cache
      # - lightwalletd + zebrad tip cache
      #
      # TODO:
      # - keep the latest $KEEP_LATEST_IMAGE_COUNT, if there are at least that many recent images, delete all the outdated images
      # - when we add testnet to the workflows, keep the latest $KEEP_LATEST_IMAGE_COUNT testnet images, 
      #   and the latest $KEEP_LATEST_IMAGE_COUNT mainnet images.
      - name: Delete old cache disks
        run: |
          DELETE_BEFORE_DATE=$(date --date="$DELETE_AGE_DAYS days ago" '+%Y%m%d')

          ZEBRAD_CHECKPOINT_IMAGES=$(gcloud compute images list --sort-by=~creationTimestamp --filter="name~^zebrad-cache-.*net-checkpoint AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME)')
          KEPT_IMAGES=0
          for IMAGE in $ZEBRAD_CHECKPOINT_IMAGES
          do
            if [[ "$KEPT_IMAGES" -lt "$KEEP_LATEST_IMAGE_COUNT" ]];
            then              
              KEPT_IMAGES=$((KEPT_IMAGES+1))
              echo "Keeping image $KEPT_IMAGES named $IMAGE"
              continue
            fi
            
            gcloud compute images delete "${IMAGE}" || continue
          done

          ZEBRAD_TIP_IMAGES=$(gcloud compute images list --sort-by=~creationTimestamp --filter="name~^zebrad-cache-.*net-tip AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME)')
          KEPT_IMAGES=0
          for IMAGE in $ZEBRAD_TIP_IMAGES
          do
            if [[ "$KEPT_IMAGES" -lt "$KEEP_LATEST_IMAGE_COUNT" ]];
            then              
              KEPT_IMAGES=$((KEPT_IMAGES+1))
              echo "Keeping image $KEPT_IMAGES named $IMAGE"
              continue
            fi
            
            gcloud compute images delete "${IMAGE}" || continue
          done
          
          LWD_TIP_IMAGES=$(gcloud compute images list --sort-by=~creationTimestamp --filter="name~^lwd-cache-.*net-tip AND creationTimestamp < $DELETE_BEFORE_DATE" --format='value(NAME)')
          KEPT_IMAGES=0
          for IMAGE in $LWD_TIP_IMAGES
          do
            if [[ "$KEPT_IMAGES" -lt "$KEEP_LATEST_IMAGE_COUNT" ]];
            then              
              KEPT_IMAGES=$((KEPT_IMAGES+1))
              echo "Keeping image $KEPT_IMAGES named $IMAGE"
              continue
            fi
            
            gcloud compute images delete "${IMAGE}" || continue
          done