deislabs / hello-wagi-grain

An example of using the Grain language to write Wagi modules

Hello Wagi for the Grain Language

Grain is a new programming language that targets WebAssembly.

This repository provides a simple module that works with Wagi. It illustrates how easy it is to write HTTP responders with Grain and Wagi.

This version is built on Grain 0.3, and relies on Grain 0.3's static compiler. Grain is a rapidly evolving language, and this code may not work on other versions of Grain.

Building

There is already a hello.gr.wasm binary checked in. To build from source, install Grain and then use this command to compile:

$ grain compile hello.gr

You can test your program with grain or wasmtime:

$ wasmtime hello.gr.wasm --env USER=mbutcher hello
==== Environment: ====
USER=mbutcher
==== Args: ====
hello.gr.wasm
hello

When deploying to Wagi, you will want to add an entry like this in WAGI's route TOML:

[[module]]
route = "/hello-grain"
module = "/path/to/hello-wagi-grain/hello.gr.wasm"

After reloading or restarting Wagi, you can execute this module:

$ curl localhost:3000/hello-grain?hello=world
==== Environment: ====
REMOTE_ADDR=127.0.0.1
SERVER_PORT=80
SERVER_PROTOCOL=http
REMOTE_USER=
HTTP_ACCEPT=*/*
X_MATCHED_ROUTE=/hello-grain
SERVER_NAME=localhost:3000
HTTP_USER_AGENT=curl/7.64.1
SCRIPT_NAME=/Users/technosophos/Code/Grain/hello-wagi-grain/hello.gr.wasm
PATH_INFO=/hello-grain
REQUEST_METHOD=GET
AUTH_TYPE=
REMOTE_HOST=127.0.0.1
HTTP_HOST=localhost:3000
QUERY_STRING=
GATEWAY_INTERFACE=CGI/1.1
PATH_TRANSLATED=/hello-grain
SERVER_SOFTWARE=WAGI/1
CONTENT_LENGTH=0
CONTENT_TYPE=
X_FULL_URL=http://localhost:3000/hello-grain
==== Args: ====
/hello-grain
hello=world