View and apply idle resources recommendations

This document explains how to view and apply idle resources recommendations for Persistent Disk volumes, IP addresses, and custom disk images.

Compute Engine helps you identify idle Persistent Disk volumes, IP addresses, and custom disk images, and provides recommendations to help you minimize waste and avoid unnecessary charges.

If you're interested in recommendations for idle virtual machine (VM) instances, then see View and apply idle VM recommendations.

Before you begin

• If you haven't already, then set up authentication. Authentication is the process by which your identity is verified for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:
  

  Select the tab for how you plan to use the samples on this page:

  Console

  When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.

  gcloud

  1. Install the Google Cloud CLI, then initialize it by running the following command:

     gcloud init

  2. Set a default region and zone.

  REST

  To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

  Install the Google Cloud CLI, then initialize it by running the following command:

  gcloud init

  For more information, see Authenticate for using REST in the Google Cloud authentication documentation.

Pricing

There are no costs associated with using idle resources recommendations.

Recommendation generation

If a resource has not been attached to a VM or other resource for 15 days, then the Recommender classifies that resource as idle. For more information about the conditions to classify a resource as idle and the recommended actions, see the following table:

Recommendation frequency

Idle resource recommendations begin 15 days after resource creation, and they are updated once every 24 hours.

Viewing recommendations

To view recommendations about idle resources, use the gcloud CLI or REST.

gcloud recommender recommendations list \
    --project=PROJECT_ID \
    --location=LOCATION \
    --recommender=RECOMMENDER_ID \
    --format=yaml

gcloud recommender recommendations list \
    --project=test-project \
    --location=us-central1-c \
    --recommender=google.compute.disk.IdleResourceRecommender \
    --format=yaml


---
content:
    operationGroups:
    - operations:
      - action: add
        resource: //compute.googleapis.com/projects/test-project/global/snapshots/$snapshot-name
        resourceType: compute.googleapis.com/Disk
        path: /
        value:
        - name: $snapshot-name
          sourceDisk: projects/test-project/locations/us-central1-c/disks/pd-name
          storageLocations: us-central1
      - action: remove
        resource: //compute.googleapis.com/projects/test-project/zones/us-central1-c/disks/pd-name
        resourceType: compute.googleapis.com/Disk
        path: /
description: Save cost by snapshotting and then deleting idle persistent disk 'pd-name'
name: projects/test-project/locations/us-central1-c/recommenders/google.compute.disk.IdleResourceRecommender/recommendations/0fd31b24-cc05-4132-8431-ed54a22dd4f1
recommenderSubtype: SNAPSHOT_AND_DELETE_DISK
lastRefreshTime:
  seconds: 1543912652
primaryImpact:
  category: COST
  costProjection:
    cost:
      currencyCode: USD
      units: '-50'
    duration:
      seconds: 2592000
stateInfo: ACTIVE
etag: "cb0e6ac2cfc0b591"

GET https://recommender.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/recommenders/RECOMMENDER_ID/recommendations

PROJECT_ID=test-project
LOCATION=us-central1-c
RECOMMENDER_ID=google.compute.disk.IdleResourceRecommender

curl -H "Authorization: Bearer $(gcloud auth print-access-token)" \
  https://recommender.googleapis.com/v1/projects/$PROJECT_ID/locations/$LOCATION/recommenders/$RECOMMENDER_ID/recommendations

{
 "description" : "Save cost by deleting idle persistent disk 'pd-name'",
 "name": "projects/test-project/locations/us-central1-c/recommenders/"
         "google.compute.disk.IdleResourceRecommender/"
         "recommendations/0fd31b24-cc05-4132-8431-ed54a22dd4f1",
 "recommenderSubtype" : "SNAPSHOT_AND_DELETE_DISK",
 "lastRefreshTime": {
   "seconds": 1543912652
 },
 "primaryImpact": {
   "category": COST,
   "costProjection": {
    "cost": {"currencyCode": "USD", "units": -50},
    "duration": { "seconds": 2592000 }
   }
 },
 "stateInfo": ACTIVE,
 "content": {
   "operationGroups" : [
    {
      "operations" : [
       {
         "action": "add",
         "resourceType": "compute.googleapis.com/Disk",
         "resource" : "//compute.googleapis.com/projects/test-project/global/snapshots/$snapshot-name",
         "value": {
           "name": "$snapshot-name",
           "sourceDisk": "projects/test-project/zones/us-central1-c/disks/pd-name",
           "storageLocations": ["us-central1"],
         }
       },
       {
         "action": "remove",
         "resourceType": "compute.googleapis/Disk",
         "resource": "//compute.googleapis.com/projects/test-project/"
                     "zones/us-central1-c/disks/pd-name"
       }
      ]
    }
   ]
 },
 "associatedInsights": [
    {
      "insight": "projects/test-project/locations/us-central1-c/insightTypes/google.compute.disk.IdleResourceInsight/insights/31326443-bcc3-4776-9b86-48879fddb656"
    }
  ],
 "etag": "cb0e6ac2cfc0b591"
}

Interpreting the recommendation response

Each recommendation that you receive through the gcloud CLI or REST contains operation groups, with operations that you can perform in serial to apply the recommendation. For example, idle Persistent Disk recommendation operation groups include one or two operations:

• If your idle Persistent Disk has data on it, then the recommendation includes an add operation to create a snapshot to back up the Persistent Disk. For example:

     {
       "action": "add",
       "resourceType": "compute.googleapis.com/Disk",
       "resource" : "//compute.googleapis.com/projects/test-project/global/snapshots/$snapshot-name",
       "path": "/",
       "value": {
         "name": "$snapshot-name",
         "sourceDisk": "projects/test-project/zones/us-central1-c/disks/pd-name",
         "storageLocations": ["us-central1"]
       }
     }
  

• A remove operation to permanently delete the idle Persistent Disk. For example:

     {
       "action": "remove",
       "resourceType": "compute.googleapis.com/Disk",
       "resource" : "//compute.googleapis.com/projects/test-project/zones/us-central1-c/disks/pd-name",
       "path": "/"
     }
  

Viewing insights for idle resource recommendations

The Recommender generates recommendations based on resource insights. By viewing insights on resources you can learn more about those resources, such as how long a resource has been detached from a VM or whether a Persistent Disk is blank.

If you want to view the insight that generated the recommendation, you can use the gcloud CLI or REST.

gcloud beta recommender insights list --project=PROJECT_NAME \
  --location=LOCATION --insight-type=INSIGHT_TYPE

GET https://recommender.googleapis.com/v1beta1/projects/PROJECT_ID/locations/LOCATION/insightTypes/INSIGHT_TYPE/insights

{
  "name": "projects/test-project/locations/us-central1-c/insightTypes/google.compute.disk.IdleResourceInsight/insights/0ec21a13-bb04-3121-7321-dc43a11cc3e2",
  "description": "Disk 'pd-name' in zone 'us-central1-c' was last used 17 days ago. Consider taking snapshot and delete it.",
  "targetResources": [
    "//compute.googleapis.com/projects/test-project/zones/us-central1-c/disks/pd-name"
  ],
  "insightSubtype": "IDLE_DISK",
  "content": {
    "diskLastUseTime": "2019-10-01 13:00:00",
    "isBlank": false,
  },
  "lastRefreshTime": "2019-10-10 13:00:00",
  "observationPeriod": "15 days",
  "stateInfo": {
    "state": "ACTIVE"
  },
  "category": "COST",
  "etag": "fds421j2349",
  "associatedRecommendations": [
    {
      "projects/test-project/locations/us-central1-c/recommenders/"
      "google.compute.disk.IdleResourceRecommender/"
      "recommendations/0fd31b24-cc05-4132-8431-ed54a22dd4f1"
    }
  ]
}

Applying idle resource recommendations

If you receive a recommendation about an idle resource and you decide that you want to apply the recommendation, then follow the instructions in the next sections.

Deleting idle IP address

See the addresses.delete method, gcloud compute addresses delete command, or the Releasing a static external IP address documentation.

Deleting idle custom images

See the images.delete method, gcloud compute images delete command, or the Deleting an image documentation.

Applying idle Persistent Disk recommendations

If you need to create a snapshot of a Persistent Disk prior to deleting it, then see Creating persistent disk snapshots.

To delete an idle Persistent Disk, see the gcloud compute disks delete command.

For information about how to recover data from a snapshot and recreate your Persistent Disk, see Restoring snapshots.