pramen-py 1.8.9

Pramen transformations written in python

Pramen-py

Cli application for defining the data transformations for Pramen.

See:

pramen-py --help

for more information.

Installation

App settings

Application configuration solved by the environment variables (see .env.example)

Add pramen-py as a dependency to your project

In case of poetry:

# ensure we have valid poetry environment
ls pyproject.toml || poetry init

poetry add pramen-py

In case of pip:

pip install pramen-py

Usage

Application configuration

In order to configure the pramen-py options you need to set corresponding environment variables. To see the list of available options run:

pramen-py list-configuration-options

Developing transformations

pramen-py uses python's namespace packages for discovery of the transformations.

This mean, that in order to build a new transformer, it should be located inside a python package with the transformations directory inside.

This directory should be declared as a package:

• for poetry

[tool.poetry]
# ...
packages = [
    { include = "transformations" },
]

• for setup.py

from setuptools import setup, find_namespace_packages

setup(
    name='mynamespace-subpackage-a',
    # ...
    packages=find_namespace_packages(include=['transformations.*'])
)

Example files structure:

❯ tree .
.
├── README.md
├── poetry.lock
├── pyproject.toml
├── tests
│  └── test_identity_transformer.py
└── transformations
    └── identity_transformer
        ├── __init__.py
        └── example_config.yaml

In order to make transformer picked up by the pramen-py the following conditions should be satisfied:

• python package containing the transformers should be installed to the same python environment as pramen-py
• python package should have defined namespace package transformations
• transformers should extend pramen_py.Transformation base class

Subclasses created by extending Transformation base class are registered as a cli command (pramen-py transformations run TransformationSubclassName) with default options. Check:

pramen-py transformations run ExampleTransformation1 --help

for more details.

You can add your own cli options to your transformations. See example at ExampleTransformation2

pramen-py pytest plugin

pramen-py also provides pytest plugin with helpful fixtures to test created transformers.

List of available fixtures:

#install pramen-py into the environment and activate it
pytest --fixtures
# check under --- fixtures defined from pramen_py.test_utils.fixtures ---

pramen-py pytest plugin also loads environment variables from .env file if it is presented in the root of the repo.

Running and configuring transformations

Transformations can be run with the following command:

pramen-py transformations run \
  ExampleTransformation1 \
  --config config.yml \
  --info-date 2022-04-01

--config is required option for any transformation. See config_example.yaml for more information.

To check available options and documentation for a particular transformation, run:

pramen-py transformations run TransformationClassName --help

where TransformationClassName is the name of the transformation.

Using as a Library

Read metastore tables by Pramen-Py API

import datetime
from pyspark.sql import SparkSession
from pramen_py import MetastoreReader
from pramen_py.utils.file_system import FileSystemUtils

spark = SparkSession.getOrCreate()

hocon_config = FileSystemUtils(spark) \
    .load_hocon_config_from_hadoop("uri_or_path_to_file")

metastore = MetastoreReader(spark) \
    .from_config(hocon_config)

df_txn = metastore.get_table(
    "transactions",
    info_date_from=datetime.date(2022, 1, 1),
    info_date_to=datetime.date(2022, 6, 1)
)

df_customer = metastore.get_latest("customer")

df_txn.show(truncate=False)
df_customer.show(truncate=False)

Development

Prerequisites:

• https://python-poetry.org/docs/#installation
• python 3.6

Setup steps:

git clone https://github.com/AbsaOSS/pramen
cd pramen-py
make install  # create virtualenv and install dependencies
make test
make pre-commit

# enable completions
# source <(pramen-py completions zsh)
# source <(pramen-py completions bash)

pramen-py --help

Load environment configuration

Before doing any development step, you have to set your development environment variables

make install

Completions

# enable completions
source <(pramen-py completions zsh)
# or for bash
# source <(pramen-py completions bash)

Deployment

From the local development environment

# bump the version
vim pyproject.toml

# deploy to the dev environment (included steps of building and publishing
#   artefacts)
cat .env.ci
make publish