OPA WebAssembly SDK for Python based on wasmtime

This is based off opa-wasm, which uses wasmer, but this targets wasmtime. This allows you to use OPA WASM binaries in Python versions above 3.10, which is the cutoff for wasmer.

It also appears to run significantly faster due to some optimizations I made and some optimizations in python in general since 3.10.

Getting Started

Install the module

pip install opa-wasmtime

Usage

There are only a couple of steps required to start evaluating the policy.

# Import the module
from opa_wasmtime import OPAPolicy

# Load a policy by specifying its file path
policy = OPAPolicy('./policy.wasm')

# Optional: Set policy data
policy.set_data({"company_name": "ACME"})

# Evaluate the policy
input = {"user": "alice"}
result = policy.evaluate(input)

Support Targets

This module has been tested on python 3.10 and above and wasmtime 27.0.2 and above.

Writing the policy

See https://www.openpolicyagent.org/docs/latest/how-do-i-write-policies/

Compiling the policy

Either use the Compile REST API or opa build CLI tool.

For example, with OPA v0.20.5+:

opa build -t wasm -e 'example/allow' example.rego

Which compiles the example.rego policy file with the result set to data.example.allow. The result will be an OPA bundle with the policy.wasm binary included.

See opa build --help for more details.