Apache APISIX가 Wasm 기능을 가능하게 하는 방법

...
func (ctx *pluginContext) OnPluginStart(pluginConfigurationSize int) types.OnPluginStartStatus {
        data, err := proxywasm.GetPluginConfiguration()
        if err != nil {
                proxywasm.LogErrorf("error reading plugin configuration: %v", err)
                return types.OnPluginStartStatusFailed
        }

        var p fastjson.Parser
        v, err := p.ParseBytes(data)
        if err != nil {
                proxywasm.LogErrorf("error decoding plugin configuration: %v", err)
                return types.OnPluginStartStatusFailed
        }
        ctx.Body = v.GetStringBytes("body")
        ctx.HttpStatus = uint32(v.GetUint("http_status"))
        if v.Exists("percentage") {
                ctx.Percentage = v.GetInt("percentage")
        } else {
                ctx.Percentage = 100
        }

        // schema check
        if ctx.HttpStatus < 200 {
                proxywasm.LogError("bad http_status")
                return types.OnPluginStartStatusFailed
        }
        if ctx.Percentage < 0 || ctx.Percentage > 100 {
                proxywasm.LogError("bad percentage")
                return types.OnPluginStartStatusFailed
        }

        return types.OnPluginStartStatusOK
}

func (ctx *httpLifecycle) OnHttpRequestHeaders(numHeaders int, endOfStream bool) types.Action {
        plugin := ctx.parent
        if !sampleHit(plugin.Percentage) {
                return types.ActionContinue
        }

        err := proxywasm.SendHttpResponse(plugin.HttpStatus, nil, plugin.Body, -1)
        if err != nil {
                proxywasm.LogErrorf("failed to send local response: %v", err)
                return types.ActionContinue
        }
        return types.ActionPause
}
...

tinygo build -o wasm_fault_injection.go.wasm -scheduler=none -target=wasi ./main.go

apisix:
        ...
wasm:
  plugins:
    - name: wasm_fault_injection
      priority: 7997
      file: wasm_fault_injection.go.wasm

curl  http://127.0.0.1:9180/apisix/admin/routes/1 \
-H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '{
    "uri":"/*",
    "upstream":{
        "type":"roundrobin",
        "timeout":{
            "connect":1,
            "read":1,
            "send":1
        },
        "nodes":{
            "httpbin.org:80":1
        }
    },
    "plugins":{
        "wasm_fault_injection":{
            "conf":"{\"http_status\":200, \"body\":\"Hello WebAssembly!\n\"}"
        }
    },
    "name":"wasm_fault_injection"
}'

curl 127.0.0.1:9080/get -v
*   Trying 127.0.0.1:9080...
* Connected to 127.0.0.1 (127.0.0.1) port 9080 (#0)
> GET /get HTTP/1.1
> Host: 127.0.0.1:9080
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Thu, 09 Feb 2023 07:46:50 GMT
< Content-Type: text/plain; charset=utf-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Server: APISIX/3.1.0
<
Hello WebAssembly!

-- apisix/wasm.lua
...
local ok, err = wasm.on_http_request_headers(plugin_ctx)
   if not ok then
       core.log.error(name, ": failed to run wasm plugin: ", err)
       return 503
   end
end
...

ngx_int_t
ngx_http_wasm_on_http(ngx_http_wasm_plugin_ctx_t *hwp_ctx, ngx_http_request_t *r,
                      ngx_http_wasm_phase_t type, const u_char *body, size_t size,
                      int end_of_body)
{
    ...

    ctx = ngx_http_wasm_get_module_ctx(r);

    if (type == HTTP_REQUEST_HEADERS) {
        cb_name = &proxy_on_request_headers;
    } else if (type == HTTP_REQUEST_BODY) {
        cb_name = &proxy_on_request_body;
    } else if (type == HTTP_RESPONSE_HEADERS) {
        cb_name = &proxy_on_response_headers;
    } else {
        cb_name = &proxy_on_response_body;
    }

    if (type == HTTP_REQUEST_HEADERS || type == HTTP_RESPONSE_HEADERS) {
        if (hwp_ctx->hw_plugin->abi_version == PROXY_WASM_ABI_VER_010) {
            rc = ngx_wasm_vm->call(hwp_ctx->hw_plugin->plugin,
                                   cb_name,
                                   true, NGX_WASM_PARAM_I32_I32, http_ctx->id, 0);
        } else {
            rc = ngx_wasm_vm->call(hwp_ctx->hw_plugin->plugin,
                                   cb_name,
                                   true, NGX_WASM_PARAM_I32_I32_I32, http_ctx->id,
                                   0, 1);
        }

    } else {
        rc = ngx_wasm_vm->call(hwp_ctx->hw_plugin->plugin,
                              cb_name,
                              true, NGX_WASM_PARAM_I32_I32_I32, http_ctx->id,
                              size, end_of_body);
    }
    ...
}