Tags
Tags are the primary way to organize assets in Dagster. You can attach several tags to an asset when it's defined, and they will appear in the UI. You can also use tags to search and filter for assets in the Asset catalog in Dagster+. They're structured as key-value pairs of strings.
Here's an example of some tags you might apply to an asset:
{"domain": "marketing", "pii": "true"}
Like owners, just pass a dictionary of tags to the tags argument when defining an asset:
import dagster as dg
# You can attach tags via the `tags` argument on the `@asset` decorator.
@dg.asset(tags={"domain": "marketing", "pii": "true"})
def my_asset(): ...
# You can also use `tags` with `AssetSpec`
my_external_asset = dg.AssetSpec(
"my_external_asset", tags={"domain": "legal", "sensitive": ""}
)
Keep in mind that tags must contain only strings as keys and values. Additionally, the Dagster UI will render tags with the empty string as a "label" rather than a key-value pair.
Tag keys
Valid tag keys have two segments: an optional prefix and name, separated by a slash (/). Prefixes are typically expected to be Python package names. For example: dagster/priority
Prefixes and name segments must each:
- Be 63 characters or less
- Contain only alphanumeric characters, dashes (
-), underscores (_), and dots (.)
Tag values
Tag values must:
- Be 63 characters or less
- Contain only alphanumeric characters, dashes (
-), underscores (_), and dots (.) - Be a string or JSON that is serializable to a string
Customizing run execution with tags
While tags are primarily used for labeling and organization, some run execution features are controlled using run tags:
- Customizing Kubernetes config
- Specifying Celery config
- Setting concurrency limits when using the
QueuedRunCoordinator - Setting the priority of different runs
System tags
Asset tags
The following table lists tags which Dagster may automatically add to assets.
| Tag | Description |
|---|---|
dagster/kind/{kind} | A tag identifying that an asset has a specific kind. For more information, see Kind tags |
Run tags
The following table lists the tags Dagster will, on occasion, automatically add to runs.
| Tag | Description |
|---|---|
dagster/op_selection | The op selection for the run |
dagster/partition | The partition of the run |
dagster/schedule_name | The schedule that triggered the run |
dagster/sensor_name | The sensor that triggered the run |
dagster/backfill | The backfill ID |
dagster/parent_run_id | The parent run of a re-executed run |
dagster/image | The Docker image tag |