9.1

Wasm middleware

This lab illustrates the use of the Dapr WASM middleware. The custom-middleware application is compiled to WASM format and registered as middleware in Dapr. The application updates a header. The application http-header-check receives incoming HTTP requests and checks if headers are set. If headers are missing a StatusCode::BAD_REQUEST gets returned.

All applications that are used throughout the entire course are listed under Installs.

How to complete this lab:

1. if not done before, run rustup target add wasm32-wasi to be able to compile to WASI format.
2. Compile the custom-go-middleware application:
   1. Navigate to the folder with cd custom-go-middleware
   2. Run tinygo build -o main.wasm -scheduler=none --no-debug -target=wasi main.go
   3. Navigate to the parent folder with cd ..
3. Compile the http-header-check application: cargo build --target wasm32-wasi --manifest-path http-header-check/Cargo.toml
4. Run the appplication and register the middleware: dapr run --app-id blankapp --dapr-http-port 3000 --app-port 8080 --resources-path ./components --config ./components/dapr-middleware-pipeline.yaml -- wasmedge http-header-check/target/wasm32-wasi/debug/http-header-check.wasm
5. Call http://localhost:3000/v1.0/invoke/blankapp/method/check-header and check if the header was set
6. Call http://localhost:8080/check-header and check that the header was not set since the middleware route and therefore didn't fire