WAGI sample using Azure Blob storage

This is an experimental repository containing WebAssembly modules running on top of WAGI (WebAssembly Gateway Interface, which allows you to run WebAssembly WASI binaries as HTTP handlers) and using Azure Blob storage.

Note that this repository is built on experimental code, and it is not guaranteed to be maintained or supported.

What does the example do?

This module exports two functions, one reads the request body and creates/updates a blob in Azure Blob Storage, based on the container and blob name from the request's query string.

The second reads the contents of a blob based on the container and blob name from the request's query string.

This example is a simplifled version of the blob sample in the azure-sdk-for-rust-wasi-samples repo here.

Building

The following tools are required to build and run the samples:

• Rust and Cargo, with the wasm32-wasi target configured.

$ rustup target add wasm32-wasi
$ cargo build --release --target wasm32-wasi --bin blob
    Finished release [optimized] target(s) in 0.09s

Running

You can run this module using either the WAGI server or [wagi-dotnet] (https://github.com/deislabs/wagi-dotnet).

wagi-dotnet

The simplehttp example contains a sample that runs this module.

WAGI server

In your modules.toml for the WAGI server, add the following:

Before running the sample, the modules, the following have to be configured (In your modules.toml for the WAGI server add the values below):

• the Storage account name and key.
• the allowed hosts where the modules are allowed to make outbound requests to - these have to be the URL of Azure services (if no allowed hosts are defined for a given module, it is not allowed to make any outbound request).

[[module]]
route = "/readblob"
module = "target/wasm32-wasi/release/blob.wasm"
entrypoint = readblob
environment = { STORAGE_ACCOUNT = "<sa>", STORAGE_MASTER_KEY = "<sa-key>" }
allowed_hosts = ["https://<sa>.blob.core.windows.net"]

[[module]]
route = "/writeblob"
module = "target/wasm32-wasi/release/blob.wasm"
entrypoint = writeblob
environment = { STORAGE_ACCOUNT = "<sa>", STORAGE_MASTER_KEY = "<sa-key>" }
allowed_hosts = ["https://<sa>.blob.core.windows.net"]

Start the server:

$ wagi --config modules.toml

Then, from another terminal instance:

$  curl -d "Test blob write" 'http://localhost:3000/writeblob?container=wagitest&blob=test' -v
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 3000 (#0)
> POST /writeblob?container=wagitest&blob=test HTTP/1.1
> Host: localhost:3000
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Length: 15
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 15 out of 15 bytes
< HTTP/1.1 200 OK
< Date: Fri, 11 Jun 2021 20:43:38 GMT
< Content-Type: text/plain
< Transfer-Encoding: chunked
<
Writing 15 bytes.
* Connection #0 to host localhost left intact

This will create or update a blob named test in the container wagitest in the storage account configured in modules.toml (note that the container should exist.)

To read the contents of the blob:

$  curl 'http://localhost:3000/readblob?container=wagitest&blob=test' -v
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 3000 (#0)
> GET /readblob?container=wagitest&blob=test HTTP/1.1
> Host: localhost:3000
> User-Agent: curl/7.58.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Fri, 11 Jun 2021 20:46:24 GMT
< Content-Type: text/plain
< Transfer-Encoding: chunked
<
Test blob write
* Connection #0 to host localhost left intact