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
  Note: If you installed the gcloud CLI previously, make sure you have the latest version by running gcloud components update.
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.
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:

Resource	Condition for resource to be classified as idle	Recommended action	Savings
Persistent Disk	All of the following must be true: The Persistent Disk was created at least 15 days ago. The Persistent Disk was never attached to a VM. The Persistent Disk is blank. The Persistent Disk isn't bound to GKE Pods.	Delete	Save 100% of the cost of that disk. For more information, see Disk and image pricing.
Persistent Disk	All of the following must be true: The Persistent Disk was detached for at least 15 days. The Persistent Disk isn't bound to GKE Pods.	Create a snapshot of the Persistent Disk, and then delete it	Reduce the maintenance cost of that disk from 35% to 92%. For more information, see Disk and image pricing.
Custom image	All of the following must be true: The image wasn't used to create a disk for at least 15 days. The image isn't used in any instance template.	Delete	Save 100% of the cost of that image. For more information, see Disk and image pricing.
External IP address	The IP address hasn't been attached to any resource for at least 15 days.	Delete	Save 100% of the cost of that IP address. For more information, see External IP address pricing.

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.

Permissions required for this task

To perform this task, you must have the following permissions:

recommender.computeDiskIdleResourceRecommendations.list on the project for idle Persistent Disk volumes
recommender.computeAddressIdleResourceRecommendations.list on the project for idle IPs
recommender.computeImageIdleResourceRecommendations.list on the project for idle custom images

Console

In the Google Cloud console, go to the All recommendations page.

Go to Recommendations

All idle resources are listed under Unused Compute Engine resources.

gcloud

Use the gcloud recommender recommendations list command with the --recommender=RECOMMENDER_ID flag:

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

Replace the following:

PROJECT_ID: the ID of your project.
LOCATION: the location that contains the resources for which you want recommendations.
- For Persistent Disk volumes specify a zone or region; for example, us-central1-c.
- For IPs:
  - To list regional IPs, you must specify a region.
  - To list global IPs, specify global. For more information about regional and global IP address resources, see IP addresses.
- For custom images specify global.
RECOMMENDER_ID: the ID of recommender
- For disks, specify google.compute.disk.IdleResourceRecommender.
- For images, specify google.compute.image.IdleResourceRecommender.
- For IPs, specify google.compute.address.IdleResourceRecommender.

For example, the following command lists idle Persistent Disk recommendations in us-central1-c for test-project:

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"

Learn more about using gcloud CLI to work with recommendations.

REST

Call the recommendations.list method and specify the recommender id, for example google.compute.disk.IdleResourceRecommender:

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

Replace the following:

PROJECT_ID: the ID of your project.
LOCATION: the location that contains the resources for which you want recommendations.
- For Persistent Disk volumes specify a zone or region; for example, us-central1-c.
- For IPs:
  - To list regional IPs, you must specify a region.
  - To list global IPs, specify global. For more information about regional and global IP address resources, see IP addresses.
- For custom images specify global.
RECOMMENDER_ID: the ID of recommender
- For disks, specify google.compute.disk.IdleResourceRecommender.
- For images, specify google.compute.image.IdleResourceRecommender.
- For IPs, specify google.compute.address.IdleResourceRecommender.

The following example shows out to send a request with curl, and the associated sample response.

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

Example JSON response for idle Persistent Disk recommendation:

{
 "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.

Permissions required for this task

To perform this task, you must have the following permissions:

recommender.computeDiskIdleResourceInsights.list on the project for idle PDs
recommender.computeAddressIdleResourceInsights.list on the project for idle IPs
recommender.computeImageIdleResourceInsights.list on the project for idle images

gcloud

Use the insights list command

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

Replace the following:

LOCATION: the location that contains the resources for which you want insights.
- For PDs specify a zone or region, for example, us-central1-c.
- For IPs:
  - To list regional IPs, you must specify a region.
  - To list global IPs, specify global. For more information about regional and global IP address resources, see IP addresses.
- For custom images specify global.
INSIGHT_TYPE: the ID of the insight type
- For disks, specify google.compute.disk.IdleResourceInsight.
- For images, specify google.compute.image.IdleResourceInsight.
- For IPs, specify google.compute.address.IdleResourceInsight.

REST

Use the insights.list method.

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

Replace the following:

PROJECT_ID: the ID of your project.
LOCATION: the location that contains the resources for which you want insights.
- For Persistent Disk volumes specify a zone or region; for example, us-central1-c.
- For IPs:
  - To list regional IPs, you must specify a region.
  - To list global IPs, specify global. For more information about regional and global IP address resources, see IP addresses.
- For custom images specify global.
INSIGHT_TYPE: the ID of the insight type
- For disks, specify google.compute.disk.IdleResourceInsight.
- For images, specify google.compute.image.IdleResourceInsight.
- For IPs, specify google.compute.address.IdleResourceInsight.

Here is an example response of an insight on an idle Persistent Disk resource:

{
  "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"
    }
  ]
}

The example response includes the following fields:

diskLastUseTime: The last time when the disk was attached to a VM. If the disk was never attached to a VM this is set to the disk's creation time.
isBlank: This field is set to true if disk is blank and was never attached to VM. Otherwise it is false.

For more information about insights, see the reference docs.

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.