bramble 1.1.0

Tree based logging for async python

bramble

Tree-based logging for python.

Traditional logging in async python will usually result in confusing, unordered logs. Many different functions and contexts may be logging to the same stream simultaneously, making it difficult to follow execution paths, or determine cause and effect. bramble solves this issue by splitting your logs into branches, which are organized in a tree like structure.

This way, you can:

• Follow the logic of your program (async, or otherwise)
• Debug concurrent tasks
• Understand how a final result was composed

Basic Usage

Creating a Logger

Getting started logging with bramble is as easy as defining a backend, and then creating a TreeLogger. It is recommended to use TreeLogger as a context manager.

import bramble
import bramble.backends

logging_backend = bramble.backends.FileWriter("some_folder_path")
with bramble.TreeLogger(logging_backend):
    ...

Logging

Once a logger has been created, you can begin logging. There are two ways to do so: First, if you are in the context of a TreeLogger, you can simply log directly.

with bramble.TreeLogger(logging_backend):
    bramble.log(message="Some message to log")

If you do not wish to use TreeLogger as a context manager, you will instead need to call the logging methods of your Treelogger's branches.

tree_logger = bramble.TreeLogger(logging_backend)
root_branch = tree_logger.root
another_branch = root_branch.branch("new branch")
another_branch.log(message="Some message to log")

When logging, the default MessageType is "USER". You may also provide arbitrary metadata that you wish to be associated with your message, in a flat dictionary. Accepted value types are: str, int, float, and bool.

Branching

Branching is bramble's core feature. The ability to split your logs, so that they remain correlated and ordered is what allows bramble to untangle complex execution paths. Once again, there is a context-based approach, and manual approach.

Context-based Branching (Recommended)

Simply decorate any functions that you wish to be a branch point. Any time these functions are called, bramble will automatically create a new branch:

@bramble.branch
async def async_fn():
    bramble.log("some log message")
    sync_fn()

@bramble.branch
def sync_fn():
    bramble.log("another log message")

with bramble.TreeLogger(logging_backend):
    asyncio.run(async_fn())

Each call to a decorated function will result in a unique log branch, and any existing log branches will receive a short message linking to the called function.

Manual Branching

If you find yourself needing to manage things by hand, simply branch any existing LogBranch object. Each branch must be provided a name.

tree_logger = bramble.TreeLogger(logging_backend)
root_branch = tree_logger.root
another_branch = root_branch.branch("new branch")
another_branch.log(message="Some message to log")

Metadata

Each of bramble's LogBranchs supports arbitrary user metadata and tags. Tags make it easier to find and identify branches, and metadata allows to you attach additional information for easy programmatic access later.

Using the @branch decorator

The easiest way to add tags and metadata to a branch is using the @branch decorator. Either use the tag and metadata keywords, or just place any number of lists and dictionaries as arguments.

@bramble.branch(tags=["tag one", "tag two"])
@bramble.branch(metadata={"item" : "value", "another": 1.0})
@bramble.branch(["a tag"])
@bramble.branch(["a tag"], {"key", 234, "key 2": 215}, ["b tag", "c tag"], {"key_2": 120}) # Dictionary which come after will update previous arguments

Using apply

If you do not know your tags or metadata before runtime, you can still use tags and metadata with your in-context branches. Simply use the apply function to apply tags and metadata to all current branches. The interface for this function is almost identical to that of the decorator.

@bramble.branch
async def my_function()
  ...
  bramble.apply(tags=["tag one", "tag two"])
  bramble.apply(["a tag"], {"key", 234, "key 2": 215}, ["b tag", "c tag"], {"key_2": 120})

Manual Tagging and Metadata

The final way to add tags or metadata to a branch is to do so directly. If you have a LogBranch object, you can simply call add_tags or add_metadata.

root = my_logger.root
branch = root.branch("my branch")
branch.add_tags(["tag_one", "tag_two"])
branch.add_metadata({"key": 234})

Demo File

For a complete example of bramble in use, please refer to demo.py.

Installing

To install with pip

pip install bramble

Extras

If you want to use bramble's Streamlit UI to view the logs that you create, you should install bramble with the ui extras.

pip install bramble[ui]

Some backends will also require extras, such as redis.

pip install bramble[redis]

UI

If you install bramble with the ui extras, bramble provides access to a simple Streamlit UI which you can use to view the logs. Simply use the command bramble-ui to run the UI. Currently, you can choose to point the UI at either a file-based or redis backend.

Usage: bramble-ui run [OPTIONS]

  Launch the bramble UI to view logs.

Options:
  --port INTEGER           Port to run the Streamlit app on.
  --backend [redis|files]  Backend to use.  [required]
  --redis-host TEXT        Redis host (if using redis backend).
  --redis-port INTEGER     Redis port (if using redis backend).
  --filepath PATH          Path to log file (if using files backend).
  --help                   Show this message and exit.

Once you have launched the UI, you can access it on your local machine via the port that you provided, in a browser of your choice.

Best Practices

Message Types

bramble currently supports 3 message types: SYSTEM, USER, and ERROR.

SYSTEM

• Branch creation (auto-handled)
• Arguments and return values (handled by either the user or the @branch decorator)

USER

• Changes to application state
• External API calls and responses
• Important control flow

ERROR

• Exceptions or error conditions (handled by the user or the @branch decorator)

Branching

Branching should be done whenever entering a new context, as mentioned above. As a general guideline, do not have a logger associated with an object or class, instead log on the function level.

Contributing

If you wish to contribute, please install bramble with the dev extras. We use the black formatter to ensure consistent code, and attempt to keep a strict 80 character line limit, where possible.