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Utility

Utility transforms provide testing or debugging functions.

utility.delay

Delays transformation for a duration of time.

Settings

FieldTypeDescriptionRequired
durationstringDuration of time to sleep.Yes

Example

sub.transform.utility.delay(
  settings={duration: '1m'}
)
sub.tf.util.delay({duration: '1m'})

utility.drop

Drops the message and returns nothing.

Example

sub.transform.utility.drop()
sub.tf.util.drop()

utility.err

Generates an error with a custom message.

Settings

FieldTypeDescriptionRequired
messagestringMessage returned in the error.Yes

Example

sub.transform.utility.err(
  settings={message: 'test'}
)
sub.tf.util.err({message: 'test'})

utility.metric.count

Generates a metric that reports the count of messages that have passed through the transform.

Settings

FieldTypeDescriptionRequired
metric.namestringName of the metric.Yes
metric.destinationobjectMetrics Destination configuration that reports the metric to an external system.Yes
metric.attributesmapMap (dictionary) of strings that are included in the metric as attributes or labels.No

Example

sub.transform.utility.metric.count(
  settings={ metric: { name: 'MessagesReceived', destination: { type: 'aws_cloudwatch_embedded_metrics' } } },
)
sub.tf.util.metric.count({ metric: { name: 'MessagesReceived', destination: { type: 'aws_cloudwatch_embedded_metrics' } } })

utility.secret

Retrieves a secret from an external secret management system and loads it into the internal Secrets Store.

Settings

FieldTypeDescriptionRequired
secretobjectThe Secret configuration for retrieving and loading the secret.Yes

Example

sub.transform.utility.secret(
  settings={ secret: sub.secrets.environment_variable(
    settings={ id: 'ENV_VAR', name: 'SUBSTATION_SECRET' }
  ) }
)
sub.tf.util.secret({ secret: sub.secrets.environment_variable({ id: 'ENV_VAR', name: 'SUBSTATION_SECRET' }) })

Use Cases

Conditionally Drop Messages

Messages can be conditionally dropped by wrapping the utility.drop transform with meta.switch:

sub.transform.meta.switch(
  settings={ cases: [
    condition=[...],
    transform=sub.tf.utility.drop(),
  ]},
)