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View and query VM metadata | Compute Engine Documentation

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Linux Windows

Every virtual machine (VM) stores its metadata in directories on a metadata server. Your VM automatically has access to this metadata server API without any additional authorization. You can use the methods explained in the following sections of this document to view and query VM metadata values:

If you encounter errors when accessing the metadata server, review Troubleshooting metadata server access issues.

Pro Tip: Maintenance events can cause occasional disruptions to the availability of the metadata server for less than one second. During this time the metadata server might return a Error 503 HTTP server response. To make your applications resilient to maintenance events, we recommend that you implement retry logic for applications that query the metadata server.

Before you begin Required roles

The following roles and permissions are needed to view custom metadata from outside the VM by using the Google Cloud console, the Google Cloud CLI, or REST. If you are programmatically querying the metadata from within the VM, you only need the roles and permissions for connecting to the VM.

To get the permissions that you need to view custom metadata from outside the VM, ask your administrator to grant you the following IAM roles:

For more information about granting roles, see Manage access to projects, folders, and organizations.

These predefined roles contain the permissions required to view custom metadata from outside the VM. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to view custom metadata from outside the VM:

You might also be able to get these permissions with custom roles or other predefined roles.

You can access all metadata by querying the metadata value entries programmatically from within a Linux or Windows VM. From within your VM, you can programmatically query your metadata values in one of the following ways by using tools such as curl on Linux or Invoke-RestMethod on Windows:

Metadata server endpoints

To programmatically query metadata, from within a VM, you have the following metadata server endpoints:

Most examples in this document use the http endpoint. However, you can access all the same metadata entries whether you use the https or the http endpoint.

Parts of a metadata request

The following table summarizes the main parts of a metadata query request.

Components Description Root URLs

All metadata values are defined as sub-paths below the following root URLs:

Request header

This header indicates that the request was sent with the intention of retrieving metadata values, rather than unintentionally from an insecure source, and lets the metadata server return the data you requested. If you don't provide this header, the metadata server denies your request.

Metadata-Flavor: Google
Note: Previously, the X-Google-Metadata-Request: True header was required in requests. Both of these headers are still supported, but we recommend that you use the Metadata-Flavor header rather than the X-Google-Metadata-Request: True header. Query a single metadata entry

Use the following commands to query a single metadata entry.

Linux
  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query. To query for a VM instance or project metadata entry, run the following command:

    curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY" -H "Metadata-Flavor: Google"

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    For example, to query the boot image for the VM, run the following query:

    user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/image" -H "Metadata-Flavor: Google"

    The output is similar to the following:

    projects/rhel-cloud/global/images/rhel-8-v20210122
Windows
  1. Connect to your Windows VM.

  2. From your Windows VM, use the Invoke-RestMethod command to make a query. To query for a VM instance or project metadata entry, run the following command:

    $value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY")
$value

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    For example, to query the boot image for the VM, run the following query:

    PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/image")
$value

    The output is similar to the following:

    projects/windows-cloud/global/images/windows-server-2019-dc-v20210112
Query metadata directory listings

Use the following commands to query metadata directory listings. Directory listings are metadata entries that contain other metadata keys. Any metadata entry ending in a trailing slash is a directory listing

Linux

  1. Connect to your Linux VM.

  2. To query for a VM instance or project metadata directory, from your Linux VM, run the following command:

      curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/" -H "Metadata-Flavor: Google"

    Replace the PATH_TO_METADATA_DIRECTORY with the path to the VM instance or project metadata directory for which you want to recursively query the listings. For example:

    For example, consider the disks/ entry, which is a directory of disks that is attached to the VM. To query the disks/ entry, complete the following steps:

    1. Run the curl tool command on the disks directory.

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/" -H "Metadata-Flavor: Google"

      The output is similar to the following:

      0/
1/
2/

    2. If you want more information about disk 0/ directory, you can then query the specific URL for that directory:

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/0/" -H "Metadata-Flavor: Google"

      The output is similar to the following:

      device-name
index
mode
type

    3. Then to query the disk type (type) for disks 0/, you can run the following:

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/0/type" -H "Metadata-Flavor: Google"

      The output is similar to the following:

      PERSISTENT
Windows

The disks/ entry is a directory of disks that is attached to the VM. To query the disks entry, complete the following steps:

  1. Connect to your Windows VM.

  2. To query for a VM instance or project metadata directory, from your Windows VM, run the following command:

    $value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/")
$value

    Replace the PATH_TO_METADATA_DIRECTORY with the path to the VM instance or project metadata directory for which you want to recursively query the listings. For example:

    For example, consider the disks/ entry, which is a directory of disks that is attached to the VM. To query the disks/ entry, complete the following steps:

    1. Use the Invoke-RestMethod command on the disks directory.

      PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/disks/")
$value

      The output is similar to the following:

      0/
1/
2/

    2. If you want more information about disk 0/ directory, you can query the specific URL for that directory:

      PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/disks/0/")
$value

      The output is similar to the following:

      device-name
index
mode
type

    3. Then to query the disk type (type) for disks 0/, you can run the following:

      PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/disks/0/type")
$value

      The output is similar to the following:

      PERSISTENT
Recursively query directory listings

If you want to return all contents under a directory, use the recursive=true query parameter with your request:

Linux

  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query. To recursively query the listings for a VM instance or project metadata directory, run the following command:

    curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/?recursive=true" -H "Metadata-Flavor: Google"

    Replace the PATH_TO_METADATA_DIRECTORY with the path to the VM instance or project metadata directory for which you want to recursively query the listings. For example:

    For example, the following command recursively queries the instance metadata listings for the disks/ directory.

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/?recursive=true" -H "Metadata-Flavor: Google"

    The output is similar to the following:

      [{"deviceName":"boot","index":0,"mode":"READ_WRITE","type":"PERSISTENT"},
  {"deviceName":"persistent-disk-1","index":1,"mode":"READ_WRITE","type":"PERSISTENT"},
  {"deviceName":"persistent-disk-2","index":2,"mode":"READ_ONLY","type":"PERSISTENT"}]

    By default, recursive contents are returned in JSON format. If you want to return these contents in text format, append the alt=text query parameter:

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/?recursive=true&alt=text" -H "Metadata-Flavor: Google"

    The output is similar to the following:

      0/device-name boot
  0/index 0
  0/mode READ_WRITE
  0/type PERSISTENT
  1/device-name persistent-disk-1
  1/index 1
  1/mode READ_WRITE
  1/type PERSISTENT
  2/device-name persistent-disk-1
  2/index 2
  2/mode READ_ONLY
  2/type PERSISTENT
Windows

  1. Connect to your Windows VM.

  2. From your Windows VM, use the Invoke-RestMethod command to make a query. To recursively query the listings for a VM instance or project metadata directory, run the following command:

      $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/?recursive=true")
  $value

    Replace the PATH_TO_METADATA_DIRECTORY with the path to the VM instance or project metadata directory for which you want to recursively query the listings. For example:

    For example, the following command recursively queries the instance metadata listings for the disks/ directory.

    PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/disks/?recursive=true")
$value

    The output is similar to the following:

    [{"deviceName":"boot","index":0,"mode":"READ_WRITE","type":"PERSISTENT"},
{"deviceName":"persistent-disk-1","index":1,"mode":"READ_WRITE","type":"PERSISTENT"},
{"deviceName":"persistent-disk-2","index":2,"mode":"READ_ONLY","type":"PERSISTENT"}]

    By default, recursive contents are returned in JSON format. If you want to return these contents in text format, append the alt=text query parameter:

    PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/instance/disks/?recursive=true&alt=text")
$value

    The output is similar to the following:

    0/device-name boot
0/index 0
0/mode READ_WRITE
0/type PERSISTENT
1/device-name persistent-disk-1
1/index 1
1/mode READ_WRITE
1/type PERSISTENT
2/device-name persistent-disk-1
2/index 2
2/mode READ_ONLY
2/type PERSISTENT
Format query output

By default, each endpoint has a predefined format for the response. Some endpoints might return data in JSON format by default, while other endpoints might return data as a string. You can override the default data format specification by using the alt=json or alt=text query parameters, which return data in JSON string format or as a plain text representation, respectively.

Linux
  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query. To change the query response data format for a VM instance or project metadata entry, run the following command:

    curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?alt=DATA_FORMAT" -H "Metadata-Flavor: Google"

    Replace the following:

Example

For example, the tags key automatically returns data in JSON format. You can return data in text format instead, by specifying the alt=text query parameter.

Default query

  user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/tags" -H "Metadata-Flavor: Google"

The output is similar to the following:

  ["http-server", "db-client", "app-server", "mysql-server"]

Query with formatting

  user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/tags?alt=text" -H "Metadata-Flavor: Google"

The output is similar to the following:

  http-server
  db-client
  app-server
  mysql-server
Windows
  1. Connect to your Windows VM.

  2. From your Windows VM, use the Invoke-RestMethod command to make a query. To change the query response data format for a VM instance or project metadata entry, run the following command:

      $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?alt=DATA_FORMAT")
  $value

    Replace the following:

Example

For example, the tags key automatically returns data in JSON format. You can return data in text format instead, by specifying the alt=text query parameter.

Default query

  PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/tags")
  $value

The output is similar to the following:

  ["http-server", "db-client", "app-server", "mysql-server"]

Query with formatting

  PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/tags?alt=text")
  $value

The output is similar to the following:

  http-server
  db-client
  app-server
  mysql-server
Query metadata changes using the wait-for-change feature

Given that metadata values can change while your VM is running, the metadata server can be notified of metadata changes by using the wait-for-change feature. With this option, the request only returns an output when your specified metadata has changed.

You can use this feature on custom metadata or server-defined metadata, so if anything changes about your VM or project, or if someone updates a custom metadata entry, you can programmatically react to the change.

For example, you can perform a request on the tags key so that the request only returns if the contents of the tags metadata has changed. When the request returns, it provides the new value of that metadata key.

The wait-for-change feature also lets you match with your request and set timeouts.

When working with thewait-for-change feature, consider the following:

To perform a wait-for-change request, query a metadata key and append the ?wait_for_change=true query parameter:

Linux
  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query. To perform a wait-for-change request for a VM instance or project metadata entry, run the following command:

    curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true" -H "Metadata-Flavor: Google"

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    After there is a change to the specified metadata key, the query returns with the new value.

Examples

In this example, if a request is made to the setInstanceTags method, the request returns with the new values:

  user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true" -H "Metadata-Flavor: Google"

The output is similar to the following:

  http-server
  db-client

You can also perform a wait-for-change request recursively on the contents of a directory:

  user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/attributes/?recursive=true&wait_for_change=true" -H "Metadata-Flavor: Google"

The metadata server returns the new contents if there is any change:

  {"foo":"bar","baz":"bat"}
Windows
  1. Connect to your Windows VM.

  2. From your Windows VM, use the Invoke-RestMethod command to make a query. To perform a wait-for-change request for a VM instance or project metadata entry, run the following command:

    $value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} `
          -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true")
$value

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    After there is a change to the specified metadata key, the query returns with the new value.

Examples

After there is a change to the specified metadata key, the query returns with the new value. In this example, if a request is made to the setInstanceTags method, the request returns with the new values:

  PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true")
  $value

The output is similar to the following:

  http-server
  db-client

You can also perform a wait-for-change request recursively on the contents of a directory:

  PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/attributes?recursive=true&wait_for_change=true")
  $value

The metadata server returns the new contents if there is any change:

  {"foo":"bar","baz":"bat"}
Use ETags

When you submit a wait-for-change query, the metadata server returns a response if anything has changed in the contents of that metadata. However, there is an inherent race condition between a metadata update and a wait-for-change request being issued, so it's useful to have a reliable way to know you are getting the latest metadata value.

To help with this, you can use the last_etag query parameter, which compares the ETag value you provide with the ETag value saved on the metadata server. If the ETag values match, then the wait-for-change request is accepted. If the ETag values don't match, this indicates that the contents of the metadata has changed since the last time you retrieved the ETag value, and the metadata server returns immediately with this latest value.

Linux VMs

To get the current ETag value for a metadata key, complete the following steps:

  1. Connect to your Linux VM.

  2. Make a request to that key and print the headers. To do this, use the curl tool with the -v flag. To get the current ETag for a VM instance or project metadata entry, run the following command:

    curl -v "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY" -H "Metadata-Flavor: Google"

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    For example, the following command gets the current ETag value for the tags instance metadata key.

      user@myinst:~$ curl -v "http://metadata.google.internal/computeMetadata/v1/instance/tags" -H "Metadata-Flavor: Google"

    The output is similar to the following:

    * About to connect() to metadata port 80 (#0)
* Trying 169.254.169.254... connected
* Connected to metadata (169.254.169.254) port 80 (#0)
> GET /computeMetadata/v1/instance/tags HTTP/1.1
> User-Agent: curl/7.19.7 (x86_64-pc-linux-gnu) libcurl/7.19.7 OpenSSL/0.9.8k zlib/1.2.3.3 libidn/1.15
> Host: metadata
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Type: application/text
< ETag: 411261ca6c9e654e
< Date: Wed, 13 Feb 2013 22:43:45 GMT
< Server: Metadata Server for VM
< Content-Length: 26
< X-XSS-Protection: 1; mode=block
< X-Frame-Options: SAMEORIGIN
<
http-server
db-client

  3. You can then use that ETag value with the curl tool command in your wait-for-change request. To use the ETag value for the wait-for-change request of instance or project metadata, run the following command:

      curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true&last_etag=ETAG" -H "Metadata-Flavor: Google"

    Replace the following:

    In this example, the following command uses the ETag value for the tags key and queries for the instance metadata entry.

      user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true&last_etag=411261ca6c9e654e" -H "Metadata-Flavor: Google"

    The metadata server matches your specified ETag value, and if that value changes, the request returns with the new contents of your metadata key.

Windows VMs

To get the current ETag value for a metadata key, complete the following steps:

  1. Connect to your Windows VM.

  2. Make a request to that key and print the headers. On Windows, use the Invoke-WebRequest command. To get the current ETag for a VM instance or project metadata entry, run the following command:

      $value = (Invoke-WebRequest -Headers @{'Metadata-Flavor' = 'Google'} `
  -Uri http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY)


    $value.Headers.ETag

    Replace the PATH_TO_METADATA_ENTRY with the path to the VM instance or project metadata key for which you want to query the value. If the key is in a sub-directory of the instance or project directory, ensure to also include the sub-directory. For example:

    For example, the following command gets the current ETag value for the tags instance metadata key.

      PS C:> 
  $value = (Invoke-WebRequest -Headers @{'Metadata-Flavor' = 'Google'} `
  -Uri http://metadata.google.internal/computeMetadata/v1/instance/tags)


    $value.Headers.ETag

    The output is similar to the following:

      * About to connect() to metadata port 80 (#0)
  * Trying 169.254.169.254... connected
  * Connected to metadata (169.254.169.254) port 80 (#0)
  > GET /computeMetadata/v1/instance/tags HTTP/1.1
  > User-Agent: curl/7.19.7 (x86_64-pc-linux-gnu) libcurl/7.19.7 OpenSSL/0.9.8k zlib/1.2.3.3 libidn/1.15
  > Host: metadata
  > Accept: /
  >
  < HTTP/1.1 200 OK
  < Content-Type: application/text
  < ETag: 411261ca6c9e654e
  < Date: Wed, 13 Feb 2013 22:43:45 GMT
  < Server: Metadata Server for VM
  < Content-Length: 26
  < X-XSS-Protection: 1; mode=block
  < X-Frame-Options: SAMEORIGIN
  <
  http-server
  db-client

  3. You can then use that ETag value in your wait-for-change request. To use the ETag value for the wait-for-change request of instance or project metadata, run the following command:

      $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
          -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true&last_etag=ETAG")
  $value

    Replace the following:

    In this example, the following command uses the ETag value for the tags key and queries for the instance metadata entry.

      PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true&last_etag=411261ca6c9e654e")
  $value

    The metadata server matches your specified ETag value, and if that value changes, the request returns with the new contents of your metadata key.

Python

The following Python sample shows how to programmatically watch the metadata server for changes.

This sample sets the initial ETag to 0. The metadata server doesn't return a response with 0 as the ETag value. When 0 is specified as the last ETag in a request, the metadata server responds with the current value and ETag. This saves a bit of the code needed to get the initial value and ETag.

Set timeouts

If you would like your wait-for-change request to time out after a certain number of seconds, you can set the timeout_sec parameter. The timeout_sec parameter limits the wait time of your request to the number of seconds you specified, and when the request reaches that limit, it returns the current contents of the metadata key.

When you set the timeout_sec parameter, the request always returns after the specified number of seconds, whether or not the metadata value has actually changed. It is only possible to set an integer value for your timeout.

Linux
  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query. To perform a wait-for-change request with a time out value for a VM instance or project metadata entry, run the following command:

      curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true&timeout_sec=TIMEOUT" -H "Metadata-Flavor: Google"

    Replace the following:

For example, the following command performs a wait-for-change request that is set to time out after 360 seconds:

  user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true&timeout_sec=360" -H "Metadata-Flavor: Google"
Windows
  1. Connect to your Windows VM.

  2. From your Windows VM, use the Invoke-RestMethod command to make a query. To perform a wait-for-change request with a time out value for a VM instance or project metadata entry, run the following command:

      $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
          -Uri "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?wait_for_change=true&timeout_sec=TIMEOUT")
  $value

    Replace the following:

For example, the following command performs a wait-for-change request that is set to time out after 360 seconds:

  PS C:> 
  $value = (Invoke-RestMethod -Headers @{'Metadata-Flavor' = 'Google'}
            -Uri "http://metadata.google.internal/computeMetadata/v1/instance/tags?wait_for_change=true&timeout_sec=360")
  $value
Query metadata by using the HTTPS metadata server endpoint

The HTTPS metadata server endpoint (https://metadata.google.internal/computeMetadata/v1) provides added security for transmission of information between the metadata server and the VM.

To use the HTTPS metadata server endpoint, the VM must meet the following requirements:

For an overview of how queries to the HTTPS metadata server endpoint are handled, see HTTPS metadata server endpoint. You can perform all the same queries to the metadata server whether you use the https or the http endpoint. However, to call the https endpoint you must specify the path to the client identity certificates and in some cases the root certificate.

The following commands demonstrate how to query the metadata server by using the https endpoint.

Linux

  1. Connect to your Linux VM.

  2. From your Linux VM, use the curl tool to make a query and specify the client identity certificate. Optionally, you can also specify the root certificate.

    curl "https://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY" \
  -E CLIENT_CERTIFICATE \
  [--cacert ROOT_CERTIFICATE] \
  -H "Metadata-Flavor: Google"

    Replace the following:

    For example, to query the boot image for a VM, run the following query:

    user@myinst:~$ 
curl "https://metadata.google.internal/computeMetadata/v1/instance/image" \
  -E /run/google-mds-mtls/client.key \
  -H "Metadata-Flavor: Google"

    The output is similar to the following:

    projects/rhel-cloud/global/images/rhel-8-v20210122

    If you see an error message, review the troubleshooting documentation.

Windows

  1. Connect to your Windows VM.

  2. Get the client identity certificate by using one of the following commands:

  3. From your Windows VM, use the Invoke-RestMethod command and specify the client identity certificate to make a query.

    PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} -Certificate CLIENT_CERTIFICATE `
          -Uri "https://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY")
$value

    Replace the following:

    For example, to query the boot image for a Windows server 2019 VM, run the following query:

    PS C:\> 
$value = (Invoke-RestMethod `
          -Headers @{'Metadata-Flavor' = 'Google'} -Certificate $cert `
          -Uri "https://metadata.google.internal/computeMetadata/v1/instance/image")
$value

    The output is similar to the following:

    projects/windows-cloud/global/images/windows-server-2019-dc-v20210112
Limitations Status codes

When you make a request to the metadata server, the metadata server returns standard HTTP status codes to indicate success or failure. Sometimes, network conditions or host events can cause the metadata server to fail your request and return an error code. In these cases, you should design your application to be fault-tolerant and to be able to recognize and handle these errors.

For a detailed list of status codes that can be returned, see Troubleshoot server codes.

You can view the custom metadata values for your Compute Engine VMs in one of the following ways:

View project metadata

To view custom metadata that applies to all VMs in your project, use one of the following methods.

Console

  1. In the Google Cloud console, go to the Metadata page.

    Go to the Metadata page

    On the Metadata page, you see a list of all custom project metadata entries for your project.

gcloud

Use the gcloud compute project-info describe command to query project metadata:

gcloud compute project-info describe --flatten="commonInstanceMetadata[]"

The output is similar to the following:

---
fingerprint: HcSFdS_1_1I=
items:
- key: ssh-keys
  value: USERNAME:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDWZ...
kind: compute#metadata
REST

To query project metadata, create a GET request to the project.get method.

Replace PROJECT_ID with your project ID.

GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID

The output is similar to the following:

"kind": "compute#project",
"id": "XXXXXXX",
"creationTimestamp": "2018-12-10T08:34:33.616-08:00",
"name": "YOUR_PROJECT",
"commonInstanceMetadata": {
  "kind": "compute#metadata",
  "fingerprint": "XXXXXCdg=",
  "items": [
    {
      "key": "enable-guest-attributes",
      "value": "TRUE"
    },
    {
      "key": "enable-os-inventory",
      "value": "true"
    },
    {
      "key": "enable-osconfig",
      "value": "TRUE"
    },
    {
      "key": "enable-oslogin",
      "value": "TRUE"
    },
    {
      "key": "sshKeys",
      "value": "XXXXX"
    }
  ]
}, ...
View zonal metadata

To view custom metadata that applies to all VM instances in a specific zone in a project, use one of the following methods.

gcloud

To query the custom zonal metadata, use the gcloud compute project-zonal-metadata describe command.

gcloud compute project-zonal-metadata describe \
    --zone=ZONE \
    --project=PROJECT_ID

Replace the following:

The output is similar to the following:

{
  "fingerprint": "VlRIl8dx9vk=",
  "metadata": {
    items: {
      "key-1": "value-1",
      "key-2": "value-2"
    }
  }
}
REST

To query the custom zonal metadata, make a GET request to the instanceSettings().get method

GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instanceSettings

Replace the following:

The output is similar to the following:

{
  "fingerprint": "VlRIl8dx9vk=",
  "metadata": {
    items: {
      "key-1": "value-1",
      "key-2": "value-2"
    }
  }
}
View instance metadata

To view metadata that applies to a single VM in your project, use one of the following methods.

Console
  1. In the Google Cloud console, go to the VM instances page.

    Go to VM instances

  2. Click the name of the VM for which you want to view metadata.

gcloud

Use the gcloud compute instances describe command to query instance metadata:

gcloud compute instances describe VM_NAME --flatten="metadata[]"

Replace VM_NAME with the name of the VM you want to find metadata for.

The output is similar to the following:

---
fingerprint: MTgTJ5m-Cjs=
items:
- key: enable-oslogin
  value: 'true'
kind: compute#metadata
REST

To query metadata for a specific VM, send a GET request to the instances.get method.

GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME

The output is similar to the following:

......
"metadata": {
"kind": "compute#metadata",
"fingerprint": "XXXXXXVo=",
"items": [
  {
    "key": "enable-oslogin",
    "value": "true"
  }
]
},....

Replace the following:

What's next

Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-08-07 UTC.

[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[[["Virtual machines (VMs) store metadata in directories on a metadata server, accessible automatically without extra authorization."],["VM metadata can be programmatically queried using tools like `curl` (Linux) or `Invoke-RestMethod` (Windows), using HTTP or HTTPS endpoints."],["To ensure data integrity, use the `wait-for-change` feature with the `last_etag` parameter to check for metadata changes and retrieve the latest values."],["The `timeout_sec` parameter can be used in `wait-for-change` requests to set a maximum wait time, after which the current metadata value will be returned."],["Custom metadata for VMs can be viewed at the project, zonal, or instance level, using the Google Cloud console, gcloud CLI, or REST API."]]],[]]

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