Features
Declare owners and metadata for features.
Features can capture metadata to inform
alerting, monitoring, and discovery.
By default, features are created as any type-annotated
variable of a class decorated with @features.
However, you may also assign these variables to the
result of the chalk.features.feature(...) function
to provide metadata.
Descriptions are parsed from the comments preceding
the feature definition. For example, you can document a
fraud_score feature with information about the values
as follows:
@features
class User:
# 0 to 100 score indicating an identity match.
# Low scores indicate safer users
fraud_score: float
...You can alternatively provide a description of a feature directly in the code. The following example is equivalent to explicitly providing the description as above:
@features
class User:
fraud_score: float = feature(description="""
0 to 100 score indicating an identity match.
Low scores indicate safer users
""")
...If both an explicit description and a comment are present,
the description will be set to the explicit value from
feature(description=...).
You can programmatically access the description for a feature
with the description(...) function:
from chalk.feature import description
print(description(User.fraud_score))You may also specify which person or group is responsible for an individual feature. The owner tag will be available in Chalk’s web portal. Alerts that do not otherwise have an owner will be assigned to the owner of the monitored feature. Owners are parsed from the source code. For example:
@features
class User:
full_name: str
# :owner: katherine.johnson@nasa.gov
fraud_score: float
...You may instead choose to specify an owner via a keyword argument to
feature().
For example:
@features
class User:
full_name: str
fraud_score: float = feature(owner="katherine.johnson@nasa.gov")
...An owner can also be assigned to every feature in a namespace via a keyword argument to @features:
@features(owner="katherine.johnson@nasa.gov")
class User:
full_name: str
fraud_score: float
# :owner: annie.easley@nasa.gov
email: str
...Here, User.full_name and User.fraud_score
assume the owner katherine.johnson@nasa.gov.
However, User.email, which specifies an owner at the feature level,
assumes the owner annie.easley@nasa.gov.
You can programmatically access the owner of a feature
with the owner(...) function:
from chalk.feature import owner
assert owner(User.email) == "annie.easley@nasa.gov"Tags are a way of adding metadata to features for use in filtering, aggregations, and visualizations. For example, you can use tags to assign features to a team and find all features for a given team.
@features
class User:
# :tags: team:identity, priority:high
fraud_score: float
...Alternatively, you may specify tags via explicit construction:
@features
class User:
fraud_score: float = feature(tags=[
"team:identity",
"priority:high",
])
...As with the owner property, tags can be assigned to all features in a namespace:
@features(tags="group:risk")
class User:
fraud_score: float
# :tags: pii
email: str
...Here, User.fraud_score inherits the tag group:risk.
The feature User.email will also inherit this tag
in addition to the tag pii.
You can programmatically access the tags for a feature
with the tags(...) function:
from chalk.feature import tags
assert tags(User.email) == ["pii", "group:risk"]