About

appmap-python is a Python package for recording AppMaps of your code. "AppMap" is a data format which records code structure (modules, classes, and methods), code execution events (function calls and returns), and code metadata (repo name, repo URL, commit SHA, labels, etc). It's more granular than a performance profile, but it's less granular than a full debug trace. It's designed to be optimal for understanding the design intent and structure of code and key data flows.

There are several ways to record AppMaps of your Python program using the appmap package:

• Run your tests (pytest, unittest) with the environment variable APPMAP=true. An AppMap will be generated for each test case.

• Use the appmap.record context manager to control recording. The context manager takes an instance of an appmap.Recording, which can be used to generate the AppMap.

• [coming soon] Run your application server with AppMap remote recording enabled, and use the AppLand browser extension to start, stop, and upload recordings.

Once you have made a recording, there are two ways to view automatically generated diagrams of the AppMaps.

The first option is to load the diagrams directly in your IDE, using the AppMap extension for VSCode.

The second option is to upload them to the AppLand server using the AppLand CLI.

Supported versions

• Python >=3.5
• Pytest >=6.1.2

Support for new versions is added frequently, please check back regularly for updates.

Installation

If your project uses pip for dependency management, add the appmap package to the requirements file or install it directly with

pip install appmap

For projects that use poetry , add the appmap package to pyproject.toml.

Configuration

Add your modules as path entries in appmap.yml:

name: my_python_app
packages:
- path: app.mod1
- path: app.mod2
  exclude:
  - MyClass
  - MyOtherClass.my_instance_method
  - MyOtherClass.my_class_method

Note that excludes are resolved relative to the associated path. So, for example, this configuration excludes app.mod2.MyClass

Environment Variables

• APPMAP if true, code will be instrumented and AppMaps will be generated. Not case-sensitive, defaults to 'false'.

• APPMAP_CONFIG specifies the configuration file to use. Defaults to appmap.yml in the current directory

• APPMAP_LOG_LEVEL specifies log level to use, from the set CRITICAL, ERROR, WARNING, INFO, DEBUG. Not case-sensitive, defaults to WARNING.

• APPMAP_OUTPUT_DIR specifies the root directory for writing AppMaps. Defaults to tmp/appmap.

Test Frameworks

appmap-python supports recording pytest and unittest test cases.

pytest

appmap-python is a pytest plugin. When it's installed in a project that uses pytest, it will be available to generate AppMaps.

root@e9987eaa93c8:/src/appmap/test/data/pytest# pip show appmap
Name: appmap
Version: 0.0.0
Summary: Create AppMap files by recording a Python application.
Home-page: None
Author: Alan Potter
Author-email: [email protected]
License: None
Location: /usr/local/lib/python3.9/site-packages
Requires: orjson, PyYAML, inflection
Required-by:
root@e9987eaa93c8:/src/appmap/test/data/pytest# APPMAP=true APPMAP_LOG_LEVEL=info pytest -svv
[2021-02-10 11:37:59,345] INFO root: appmap enabled: True
[2021-02-10 11:37:59,350] INFO appmap._implementation.configuration: ConfigFilter, includes {'simple'}
[2021-02-10 11:37:59,350] INFO appmap._implementation.configuration: ConfigFilter, excludes set()
===================================================================== test session starts =====================================================================
platform linux -- Python 3.9.1, pytest-6.2.2, py-1.10.0, pluggy-0.13.1 -- /usr/local/bin/python
cachedir: .pytest_cache
rootdir: /src, configfile: pytest.ini
plugins: appmap-0.0.0
collected 1 item

test_simple.py::test_hello_world [2021-02-10 11:37:59,482] INFO appmap.pytest: starting recording /tmp/pytest/test_hello_world.appmap.json
[2021-02-10 11:37:59,484] INFO appmap._implementation.configuration: included class simple.Simple
[2021-02-10 11:37:59,484] INFO appmap._implementation.configuration: included function simple.Simple.hello
[2021-02-10 11:37:59,489] INFO appmap._implementation.configuration: included function simple.Simple.hello_world
[2021-02-10 11:37:59,490] INFO appmap._implementation.configuration: included function simple.Simple.world
[2021-02-10 11:37:59,828] INFO appmap.pytest: wrote recording /tmp/pytest/test_hello_world.appmap.json
PASSED

====================================================================== 1 passed in 0.45s ======================================================================

unittest

import appmap.unittest. Instruments subclasses of unittest.TestCase and records each test_* function in the subclasses. You can also use python -m appmap.unittest exactly like python -m unittest and leave your code unmodified (just remember to set the APPMAP=true environment variable).

Run your tests

Once you've configured your tests to generate AppMaps, run the tests with the APPMAP=true in the environment. For example, to run a pytest test suite:

$ APPMAP=true pytest

Remote Recording [coming soon]

appmap-python supports remote recording of Django and Flask web applications. Import the appropriate remote recording support into your web app.

Django

import appmap.django. Adds /_appmap/record routes to a Django app.

Flask

from flask import Flask

from appmap.flask import AppmapFlask

app = Flask(__name__)

appmap_flask = AppmapFlask(app)

Adds /_appmap/record routes to a Flask app.

Run your web app

Once you've configured your web app to add the remote-recording routes, you can use the routes to manage recordings. The browser extension, appland CLI, or just plain cURL will all work for this.

As when running tests, start the web server with APPMAP=true in the environment. For example, to start a Django app:

$ APPMAP=true python manage.py runserver

An app with remote recording enabled supports these routes:

• POST /_appmap/record Starts a new recording

  200 if the recording was started successfully 409 if there's already a recording in progress

• GET /_appmap/record Returns JSON describing current recording state 200 with body

  {
    "enabled": true
  }

  enabled indicates whether recording has been enabled

• DELETE /_appmap/record Returns AppMap as JSON 200 with AppMap as body 404 if there's no recording in progress

Context manager

You can use appmap.record as a context manager to record your code.

With a file called record_sample.py like this

import os
import sys

import appmap

r = appmap.Recording()
with r:
    import sample
    print(sample.C().hello_world(), file=sys.stderr)

with os.fdopen(sys.stdout.fileno(), "wb", closefd=False) as stdout:
    stdout.write(appmap.generation.dump(r))
    stdout.flush()

and a source file called sample.py like this

class C:
    def make_str(self, s):
        return s;

    def hello_world(self):
        return f'{self.make_str("Hello")} {self.make_str("world!")}'

as well as an appmap.yml

name: sample
packages:
- path: sample

you can generate a recording of the code

% APPMAP=true python record_sample.py > record_sample.appmap.json
% jq '.events | length' record_sample.appmap.json
6
% jq < record_sample.appmap.json | head -10
{
  "version": "1.4",
  "metadata": {
    "language": {
      "name": "python",
      "engine": "CPython",
      "version": "3.9.1"
    },
    "client": {
      "name": "appmap",

Development

Python version support

As a package intended to be installed in as many environments as possible, appmap-python needs to avoid using features of Python or the standard library that were added after the oldest version currently supported (see above).

The Travis build uses vermin to help weed out the use of some invalid features. Additionally, tests are run using all supported versions of Python.

Dependency management

poetry for dependency management:

% brew install poetry
% cd appmap-python
% poetry install

Linting

pylint for linting:

% cd appmap-python
% poetry run pylint appmap

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

[Note that the current configuration requires a 10.0 for the Travis build to pass. To make this easier to achieve, convention and refactoring checks have both been disabled. They should be reenabled as soon as possible.]

Testing

pytest

pytest for testing:

% cd appmap-python
% poetry run pytest

tox

Additionally, the tox configuration provides the ability to run the tests for all supported versions of Python and django:

% cd appmap-python
% poetry run tox

Note that tox requires the correct version of Python to be installed before it can create a test environment. pyenv is an easy way to manage multiple versions of Python.

Code Coverage

coverage for coverage:

% cd appmap-python
% poetry run coverage run -m pytest
% poetry run coverage html
% open htmlcov/index.html