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Using the Python Host SDK

Check your installation

Please be sure you've installed Extism before continuing with this guide.

1. Install the Python library​

Install via Pip:

pip3 install extism

Install via Poetry:

poetry add extism

2. Import the library and use the APIs​

Count Vowels Plugin

code.wasm in this example is our example plugin that counts vowels. If you want to run this, download it first and set the path:

curl https://raw.githubusercontent.com/extism/extism/main/wasm/code.wasm > code.wasm
app.py
import sys
import os
import json
import hashlib

from extism import Plugin, Context

if len(sys.argv) > 1:
    data = sys.argv[1].encode()
else:
    data = b"some data from python!"

# a Context provides a scope for plugins to be managed within. creating multiple contexts
# is expected and groups plugins based on source/tenant/lifetime etc.
with Context() as context:
    wasm = open("../wasm/code.wasm", 'rb').read()
    hash = hashlib.sha256(wasm).hexdigest()
    config = {"wasm": [{"data": wasm, "hash": hash}], "memory": {"max": 5}}

    plugin = context.plugin(config)
    # Call `count_vowels`
    j = json.loads(plugin.call("count_vowels", data))
    print("Number of vowels:", j["count"])

Need help?​

If you've encountered a bug or think something is missing, please open an issue on the Extism GitHub repository.

There is an active community on Discord where the project maintainers and users can help you. Come hang out!