Class Reference

The ctx class passes execution context metadata, telemetry interfaces, secrets, and metrics instruments to your function handler.

The ctx object is passed as an argument to both the event initializer function (init(ctx)) and the event handler function (handler()).

It provides access to the following capabilities:

The embedded tracer is a standard OpenTelemetry tracer. You can use ctx.tracer or the helper methods ctx.start_as_current_span() and ctx.start_as_current_event_span() to generate telemetry spans visualizable in DataEngine.

The embedded logger (ctx.logger) is an OpenTelemetry-integrated Python logger. Use standard severity levels (info, warning, error, etc.) to produce trace-correlated execution logs.

Note

By default, the runtime also captures stdout (such as print() statements) and logs from standard Python loggers, automatically transmitting them via OpenTelemetry to VAST DataEngine.

You can use the ctx object to create custom attributes. Custom attributes must be initialized by the init() function and then they can be accessed in the event handler path.

For example:

def init(ctx):
    # One-time initialization
    ctx.logger.info("Initialized...")

    # Initialize custom attributes on the context object
    ctx.myvalue = "some_value"
    ctx.counter = 1


def handler(ctx, event):
    # Event processing path
    ctx.logger.info(f"Handler processing event: {event}")

    # Access and update custom attributes set during init
    ctx.counter += 1

    return f"myvalue={ctx.myvalue}, counter={ctx.counter}"

Functions can register and emit custom OpenTelemetry metrics using helper methods on the ctx object:

Secrets mounted to your pipeline or function deployment are accessible via the ctx.secrets dictionary. If no secrets directory is mounted, ctx.secrets returns an empty dictionary.

The ctx.pipeline_triggers_map property provides access to the pipeline configuration map, detailing downstream function trigger relationships and conditional trigger labels.

Base class for all event types. It provides access to CloudEvent attributes, OpenTelemetry trace context, conditional trigger labeling, and type-casting methods (as_element_event(), as_schedule_event(), as_function_event(), as_manual_event()).

Base class for all event types. Returns the following properties:

"ce_time": datetime.now(timezone.utc).isoformat(timespec="milliseconds").replace("+00:00", "Z"),

Represents element type events. This type of event is produced by an element type trigger that watches for the creation or removal of an element (S3 object) or tag (s3 object tag) in a source view (bucket).

Includes all VastEvent properties plus:

Represents function type events. This type of event is sent by a function to another function if the first function triggers the second function in a deployed pipeline.

Includes all VastEvent properties plus:

Note

For FunctionVastEvent, subtype is not available and returns None. Accessing trigger or trigger_id will log a warning directing you to use function_trigger instead.

Represents schedule type events. This type of event is produced by a schedule type trigger that produces events on a configured schedule.

Includes all VastEvent properties plus:

Represents manual type events triggered directly by a user.

This class inherits all base properties and methods from VastEvent without adding additional specialized properties. It provides the as_manual_event() casting method.

A wrapper class around a list of VastEvent objects designed for batch event processing.