Spans

If you haven't already, we recommend reading OpenTelemetry first.

Lilypad implements a span context manager that makes it easy to instrument a block of code:

import lilypad

lilypad.configure()

with lilypad.span("Something") as span:  
    span.log("Did something...")  

import lilypad

lilypad.configure()

with lilypad.span("Something") as span:  
    span.log("Did something...")  

This will automatically capture information such as the latency of the code run within the span, including any calls to log that you make inside of the block.

Logging Levels

The span context manager provides additional convenience methods for common logging levels:

• log — alias for the info method.
• info — log an informational message.
• debug — log a debug message.
• warning — log a warning message.
• error — log an error message.
• critical — log a critical message.

For example, you may want to catch and log and exception:

import lilypad

lilypad.configure()

with lilypad.span("Possible Failure") as span:
    try:
        # do something that could error
        raise RuntimeError("For testing.")
    except RuntimeError as e:
        span.error(f"Runtime exception caught: {e}")  

import lilypad

lilypad.configure()

with lilypad.span("Possible Failure") as span:
    try:
        # do something that could error
        raise RuntimeError("For testing.")
    except RuntimeError as e:
        span.error(f"Runtime exception caught: {e}")  

Metadata

You can also capture arbitrary structured metadata:

import lilypad

lilypad.configure()

with lilypad.span("Structured Metadata") as span:
    span.metadata({"key": "value"})  

import lilypad

lilypad.configure()

with lilypad.span("Structured Metadata") as span:
    span.metadata({"key": "value"})  

Calling metadata multiple times will merge the dictionaries.

Nested Spans

Lilypad will properly capture nested spans as what we call Traces, which are really just a collection of nested spans that share a single common parent.

import lilypad

lilypad.configure()

with lilypad.span("Parent Span") as parent_span:
    parent_span.log("I'm the parent!")
    with lilypad.span("Child span") as child_span:  
        child_span.log("I'm the child!")  

import lilypad

lilypad.configure()

with lilypad.span("Parent Span") as parent_span:
    parent_span.log("I'm the parent!")
    with lilypad.span("Child span") as child_span:  
        child_span.log("I'm the child!")  

The project home page will only display the parent in each row. You can click the dropdown to view the entire collection of spans contained within that trace: