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.
ctrl+v to paste the copied code blocks.Select the tab for how you plan to use the samples on this page:
When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.
Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:
gcloud initIf you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
To use the Python samples on this page in a local development environment, install and initialize the gcloud CLI, and then set up Application Default Credentials with your user credentials.
Install the Google Cloud CLI.
If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
If you're using a local shell, then create local authentication credentials for your user account:
gcloud auth application-default login
You don't need to do this if you're using Cloud Shell.
If an authentication error is returned, and you are using an external identity provider (IdP), confirm that you have signed in to the gcloud CLI with your federated identity.
For more information, see Set up authentication for a local development environment.
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.
If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
For more information, see Authenticate for using REST in the Google Cloud authentication documentation.
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:
roles/compute.instanceAdmin.v1)
on the VM or projectroles/iam.serviceAccountUser)
on the service account or project
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:
The following permissions are required to view custom metadata from outside the VM:
compute.projects.get
on the project
compute.instanceSettings.get
on the instance settings in the required zone in the project
compute.instances.get
on the VM
iam.serviceAccounts.actAs
on the service accounts or project
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:
wait-for-change featureTo programmatically query metadata, from within a VM, you have the following metadata server endpoints:
http://metadata.google.internal/computeMetadata/v1) or its IP address
(169.254.169.254). Use the IPv4 address even with
IPv6-only instances.For Shielded VMs, you can query the metadata server by using one of the following:
http://metadata.google.internal/computeMetadata/v1https://metadata.google.internal/computeMetadata/v1). This https endpoint is
available in Preview.
To see the format for querying the https endpoint, see
Query metadata by using the HTTPS metadata server endpoint.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.
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 |
Use the following commands to query a single metadata entry.
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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")
$value
The output is similar to the following:
projects/windows-cloud/global/images/windows-server-2019-dc-v20210112
Use the following commands to query metadata directory listings. Directory listings are metadata entries that contain other metadata keys. Any metadata entry ending in a trailing slash is a directory listing
Connect to your Linux VM.
To query for a VM instance or project metadata directory, from your Linux VM, run the following command:
curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/" -H "Metadata-Flavor: Google"
Replace the PATH_TO_METADATA_DIRECTORY with the path to
the VM instance or project metadata directory for which you want to recursively
query the listings. For example:
attributes project metadata directory entry, the
path to specify is project/attributes/.
disks VM instance metadata directory entry, the path
to specify is instance/disks/.
For example, consider the disks/ entry, which is a directory of disks
that is attached to the VM. To query the disks/ entry, complete the
following steps:
Run the curl tool
command on the disks directory.
user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/disks/" -H "Metadata-Flavor: Google"
The output is similar to the following:
0/ 1/ 2/
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
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
The disks/ entry is a directory of disks that is attached to the VM.
To query the disks entry, complete the following steps:
Connect to your Windows VM.
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:
attributes project metadata directory entry, the
path to specify is project/attributes/.
disks VM instance metadata directory entry, the path
to specify is instance/disks/.
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:
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/
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
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")
$value
The output is similar to the following:
PERSISTENT
If you want to return all contents under a directory, use the recursive=true
query parameter with your request:
Connect to your Linux VM.
From your Linux VM, use the curl tool
to make a query. To recursively query the listings for a VM instance or
project metadata directory, run the following command:
curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_DIRECTORY/?recursive=true" -H "Metadata-Flavor: Google"
Replace the PATH_TO_METADATA_DIRECTORY with the path to
the VM instance or project metadata directory for which you want to recursively
query the listings. For example:
attributes project metadata directory entry, the
path to specify is project/attributes/.
disks VM instance metadata directory entry, the path
to specify is instance/disks/.
For example, the following command recursively queries the instance
metadata listings for the disks/ directory.
user@myinst:~$ 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
Connect to your Windows VM.
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:
attributes project metadata directory entry, the
path to specify is project/attributes/.
disks VM instance metadata directory entry, the path
to specify is instance/disks/.
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")
$value
The output is similar to the following:
0/device-name boot 0/index 0 0/mode READ_WRITE 0/type PERSISTENT 1/device-name persistent-disk-1 1/index 1 1/mode READ_WRITE 1/type PERSISTENT 2/device-name persistent-disk-1 2/index 2 2/mode READ_ONLY 2/type PERSISTENT
By default, each endpoint has a predefined format for the response. Some endpoints
might return data in JSON format by default, while other endpoints might return
data as a string. You can override the default data format specification by
using the alt=json or alt=text query parameters, which return data in JSON
string format or as a plain text representation, respectively.
From your Linux VM, use the curl tool
to make a query. To change the query response data format for a VM
instance or project metadata entry, run the following command:
curl "http://metadata.google.internal/computeMetadata/v1/PATH_TO_METADATA_ENTRY?alt=DATA_FORMAT" -H "Metadata-Flavor: Google"
Replace the following:
Replace the PATH_TO_METADATA_ENTRY with the path to
the VM instance or project metadata key for which you want to query the value.
If the key is in a sub-directory of the instance or project directory, ensure
to also include the sub-directory. For example:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
DATA_FORMAT: the format in which you want
the query response data—for example, text or json.For example, the tags key
automatically returns data in JSON format. You can return data in text
format instead, by specifying the alt=text query parameter.
Default query
user@myinst:~$ 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
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
DATA_FORMAT: the format in which you want
the query response data—for example, text or json.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")
$value
The output is similar to the following:
http-server db-client app-server mysql-server
By default, when you query the metadata server for an OAuth2 access token from the /computeMetadata/v1/instance/service-accounts/default/token endpoint, the returned token includes all scopes that you specified for the service account when you created or updated the instance.
To request an access token downscoped to specific, limited scopes, you must use the scopes query parameter in combination with the enforce_scopes=true query parameter. The scopes you request must be a subset of the scopes you specified for the instance.
From your Linux VM, use the curl tool to request a token with limited scopes:
curl "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token?enforce_scopes=true&scopes=SCOPE_1,SCOPE_2,..." -H "Metadata-Flavor: Google"
Replace SCOPE_1,SCOPE_2,... with a comma-separated list of OAuth2 scopes.
For example, to request a token downscoped to read-only access for Cloud Storage:
user@myinst:~$ curl "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token?enforce_scopes=true&scopes=https://www.googleapis.com/auth/devstorage.read_only" -H "Metadata-Flavor: Google"
The output is similar to the following:
{
"access_token": "ya29.c....",
"expires_in": 3599,
"token_type": "Bearer"
}
From your Windows VM, use the Invoke-RestMethod command to request a token with limited scopes:
$value = (Invoke-RestMethod `
-Headers @{'Metadata-Flavor' = 'Google'} `
-Uri "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token?enforce_scopes=true&scopes=SCOPE_1,SCOPE_2,...")
$value
Replace SCOPE_1,SCOPE_2,... with a comma-separated list of OAuth2 scopes.
For example, to request a token downscoped to read-only access for Cloud Storage:
PS C:\>
$value = (Invoke-RestMethod `
-Headers @{'Metadata-Flavor' = 'Google'} `
-Uri "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token?enforce_scopes=true&scopes=https://www.googleapis.com/auth/devstorage.read_only")
$value
The output is similar to the following:
access_token : ya29.c.... expires_in : 3599 token_type : Bearer
Alternatively, you can enforce this downscoping behavior for all token requests by setting the enable-access-token-enforce-scopes custom metadata key to true at the instance or project level. If you set this key to true, the metadata server automatically downscopes any token request that includes the scopes parameter, even if the request doesn't include enforce_scopes=true.
wait-for-change featureGiven 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:
You can only perform a wait-for-change request on a
metadata endpoint or recursively on the contents of a directory. You cannot
perform a wait-for-change request on a directory listing.
If you try to do this, the metadata server fails your request and returns a
400 Invalid Request error.
You cannot perform a wait-for-change request for a service
account token. If you try to make a wait-for-change request to the service
account token URL, the request fails immediately and returns a
400 Invalid Request error.
To perform a wait-for-change request, query a metadata key and append the
?wait_for_change=true query parameter:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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"}
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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"}
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.
To get the current ETag value for a metadata key, complete the following steps:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
ETAG: the ETag value for the metadata key.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.
To get the current ETag value for a metadata key, complete the following steps:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
ETAG: the ETag value for the metadata key.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.
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.
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.
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
TIMEOUT: the time out value.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"
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
TIMEOUT: the time out value.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
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:
disable-https-mds-setup metadata key for the VM must be
set to FALSE.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.
Connect to your Linux VM.
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:
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
CLIENT_CERTIFICATE: the path to the
client identity certificate: /run/google-mds-mtls/client.key.ROOT_CERTIFICATE: the path to the
root certificate: /run/google-mds-mtls/root.crt. You must specify this
value if the root certificate isn't added to the OS trust store.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.
Connect to your Windows VM.
Get the client identity certificate by using one of the following commands:
$cert = Get-PfxCertificate -FilePath "C:\ProgramData\Google\Compute Engine\mds-mtls-client.key.pfx"
$cert = Get-ChildItem Cert:\LocalMachine\My | Where-Object { $_.Issuer -like "google.internal" }
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:
CLIENT_CERTIFICATE: the path to the
client identity certificate
on the VM. This is the $cert variable that is set in the previous step.
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:
project-id metadata key, which is stored in
project metadata, specify project/project-id.
image metadata key, which is stored in VM instance
metadata, specify instance/image.
enable-oslogin which can be stored in the
attributes sub-directory of either project or VM instance metadata,
specify either project/attributes/enable-oslogin or
instance/attributes/enable-oslogin depending on your use case.
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
Any requests that contain the header X-Forwarded-For are
automatically rejected by the metadata server. This header generally
indicates that the request was proxied and might not be a request made by an
authorized user. For security reasons, all such requests are rejected.
When you use the curl command to retrieve metadata from the server, note that
some encoded characters aren't supported in the request path.
Encoded characters are only supported in the query path.
For example, the following request might not work:
curl "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/123456789-compute%40developer.gserviceaccount.com/?query_path=https%3A%2F%2Flocalhost%3A8200%2Fexample%2Fquery&another_param=true" -H "Metadata-Flavor: Google"
For this request to work, you must replace the unsupported encoded character
in the request path (%40) with the equivalent accepted value (@).
curl "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/1234567898-compute@developer.gserviceaccount.com/?query_path=https%3A%2F%2Flocalhost%3A8200%2Fexample%2Fquery&another_param=true" -H "Metadata-Flavor: Google"
The following table summarises the encoded characters that aren't supported in a request path.
| Encoded character | Accepted value |
|---|---|
| %21 | ! |
| %24 | $ |
| %27 | ' |
| %28 | ( |
| %29 | ) |
| %2A | * |
| %2C | , |
| %40 | @ |
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:
To view custom metadata that applies to all VMs in your project, use one of the following methods.
In the Google Cloud console, go to the Metadata page.
On the Metadata page, you see a list of all custom project metadata entries for your project.
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
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"
}
]
}, ...
To view custom metadata that applies to all VM instances in a specific zone in a project, use one of the following methods.
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:
PROJECT_ID: your project IDZONE: the zone for which you want to view the
zonal metadata.The output is similar to the following:
{
"fingerprint": "VlRIl8dx9vk=",
"metadata": {
items: {
"key-1": "value-1",
"key-2": "value-2"
}
}
}
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:
PROJECT_ID: your project IDZONE: the zone for which you want to view the
zonal metadata.The output is similar to the following:
{
"fingerprint": "VlRIl8dx9vk=",
"metadata": {
items: {
"key-1": "value-1",
"key-2": "value-2"
}
}
}
To view metadata that applies to a single VM in your project, use one of the following methods.
Click the name of the VM for which you want to view metadata.
SSH keys for this VM. In the Security and access section, view the SSH keys field.
A value of None indicates there are no SSH keys stored in instance
metadata.
Any other value indicates that there are SSH keys stored in instance metadata.
SSH keys for a project. In the Security and access section, view the Block project-wide SSH keys field.
A value of On indicates that the value of the metadata key
block-project-ssh-keys is TRUE in instance metadata.
A value of Off indicates that the value of the metadata key
block-project-ssh-keys is FALSE, or that the key isn't set.
All other custom metadata. View the Custom metadata section. You see all custom metadata keys and values, other than SSH key metadata.
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
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:
PROJECT_ID: your project IDZONE: the zone where the VM is locatedVM_NAME: the name of the VMExcept 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 2026-06-09 UTC.