This page describes how to use labels with Cloud Workstations resources.

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## What are labels?

A label is a key-value pair that you can assign to Google Cloud instances.
They help you organize these resources and manage your costs at scale, with the
granularity you need. You can attach a label to each resource, then filter the
resources based on their labels. Information about labels is forwarded to the billing system that
lets you break down your billed charges by label. With built-in [billing reports](https://docs.cloud.google.com/billing/docs/how-to/reports),
you can filter and group costs by resource labels.
You can also use labels to
query [billing data exports](https://docs.cloud.google.com/billing/docs/how-to/bq-examples).

## Requirements for labels

The labels applied to a resource must meet the following
requirements:

- Each resource can have up to 64 labels.
- Each label must be a key-value pair.
- Keys have a minimum length of 1 character and a maximum length of 63 characters, and cannot be empty. Values can be empty, and have a maximum length of 63 characters.
- Keys and values can contain only lowercase letters, numeric characters, underscores, and dashes. All characters must use UTF-8 encoding, and international characters are allowed. Keys must start with a lowercase letter or international character.
- The key portion of a label must be unique within a single resource. However, you can use the same key with multiple resources.

These limits apply to the key and value for each label, and to the
individual Google Cloud resources that have labels. There
is no limit on how many labels you can apply across all resources
within a project.

## Common uses of labels

Here are some common use cases for labels:

- **Team or cost center labels** : Add labels based on team or
  cost center to distinguish instances owned by different
  teams (for example, `team:research` and `team:analytics`). You can use this
  type of label for cost accounting or budgeting.

- **Component labels** : For example, `component:redis`,
  `component:frontend`, `component:ingest`, and `component:dashboard`.

- **Environment or stage labels** : For example,
  `environment:production` and `environment:test`.

- **State labels** : For example, `state:active`,
  `state:readytodelete`, and `state:archive`.

- **Ownership labels** : Used to identify the teams that are
  responsible for operations, for example: `team:shopping-cart`.


+ **Virtual machine labels**: A label can be
attached to a virtual machine. Virtual machine tags that you defined in the
past appear as a label without a value.

> [!NOTE]
> **Note:** Don't include sensitive information in labels, including personally identifiable information, such as an individual's name or title. Labels are not designed to handle sensitive information.

We don't recommend creating large numbers of unique labels, such as
for timestamps or individual values for every API call.
The problem with this approach is that when the values change frequently or with
keys that clutter the catalog, this makes it difficult to effectively filter and
report on resources.

## Labels and tags

Labels can be used as queryable annotations for resources, but can't be used
to set conditions on policies. Tags provide a way to conditionally allow or
deny policies based on whether a resource has a specific tag, by providing fine-grained
control over policies. For more information, see the
[Tags overview](https://docs.cloud.google.com/resource-manager/docs/tags/tags-overview).

For more information about Google Cloud labels, see [Organize resources using
labels](https://docs.cloud.google.com/compute/docs/labeling-resources#filter).

For more information about tagging Cloud Workstations resources, see [Tag Cloud Workstations resources](https://docs.cloud.google.com/workstations/docs/tags).

## Cloud Workstations resource labels

Cloud Workstations automatically applies the following labels to all resources:

- `workstation_cluster_id`
- `workstation_config_id`
- `workstation_id`
- `workstation_location`
- `goog-drz-workstation-location`
- `goog-drz-workstation-uuid`
- `goog-workstations`

## Custom Cloud Workstations labels

You can also add your custom labels to workstation clusters, workstation
configurations and workstations, which recursively applies them to all
underlying Compute Engine resources, although not to the underlying
Cloud Workstations API resources. To label Compute Engine resources for
individual workstations, be sure to add labels for each individual workstation.

Use the `labels` field when calling the
[Cloud Workstations API](https://docs.cloud.google.com/workstations/docs/apis).

For example, in the sample `config.json` file that follows, `webserver` is a key
and `backend` is the corresponding value. Similarly, `media` is a key and
`images` is the corresponding value.

        {
          "idleTimeout": "7200s",
          "host": {
            "gce_instance": {
              "machine_type": "e2-standard-8",
              "pool_size": 1
            }
          },
          "persistentDirectories": [
            {
            "mountPath": "/home",
            "gcePd": {
              "sizeGb": 200,
              "fsType": "ext4"
            }
          }
          ],
          "labels": {
            "webserver": "backend",
            "media": "images"
          }
        }