Use Extism PDK for С to send HTTP(s) requests from inside WASM

This devcontainer is configured to provide you a wasi-sdk 20.0.

Instructions for this devcontainer

Tested with Extism C PDK v1.0.1, Extism CLI v1.5.2.

Preparation

1. Open this repo in devcontainer, e.g. using Github Codespaces. Type or copy/paste following commands to devcontainer's terminal.

2. Download the extism-pdk.h header file, the only required part of Extism C PDK:

wget https://raw.githubusercontent.com/extism/c-pdk/v1.0.1/extism-pdk.h

Building

1. Compile the example:

clang -o HTTPRequestingPlugin.wasm -mexec-model=reactor httpget.c

Test with Extism CLI

For testing purposes, you can invoke functions from Extism plugins with Extism CLI.

1. Install Extism CLI from Github releases:

wget https://github.com/extism/cli/releases/download/v1.5.2/extism-v1.5.2-linux-amd64.tar.gz -O /tmp/extism.tar.gz
tar -xzf /tmp/extism.tar.gz -C /tmp ; mv /tmp/extism .

And now you have extism binary in current folder.

2. Run httpget function from extism plugin with CLI, allowing outbound connections to all hosts:

./extism call HTTPRequestingPlugin.wasm httpget --allow-host '*' --wasi

Finish

Perform your own experiments if desired.

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An additional example using low-level API is in deprecated-extismpointer folder.

This devcontainer is based on ideas from dev-wasm/dev-wasm-c.

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