Embedding user code in your app using Extism

Every application I love has some kind of power-user mode where I can add my own code or scripting to make it useful to me. Simple examples are Firefox with its addons or VLC with its plugins. Ideally, any significant or valuable application should have such a feature. But as a developer or builder, it’s not easy to build such a feature securely. I have tried it before with embedding Lua with some restrictions. But it isn’t great in sandboxing. I’ve always had an eye on the WASM-based implementation because browsers have decent sandboxing. Very recently, when I was updating Navidrome, I came across its plugin system, which uses Extism and is based on WebAssembly. Ideally, at some point, even WordPress can do this, allowing us to sandbox plugins. So I wrote a simple plugin to try out this infrastructure. I wrote a plugin with internet access to a given URL. Its only goal is to test the plugin’s ability to make web API calls in a controlled way. And to explore how plugins work. The…