Welcome to the next installment of the “Writing Envoy WASM Filters The Hardest Way” franchise. In this episode, our silly hero has decided to put together the lessons learned in the previousepisodes and define an Envoy WASM filter using only LLVM IR, a magnetized needle, and a steady hand. Now that we have figured out how to write a WASM filter from scratch, the jump to LLVM IR is far smaller. We can write a source file llvm.ll that maps onto the correct WASM ABI pretty easily.
