Environment variable of serverless computing

I am trying to test rust compiled wasm on 2 Chinese serverless computing platform, if the language is nodejs, I can get environment variable by

    var value = process.env.myKey

Same as Amazon lambda. According to Amazon rust lambda's doc, I should be able to get it by std::env::var("myKey"), so I tried the same on the 2 platform, both returned error of not exist. Then I tried to list all variables by:

    let mut varsOut:HashMap<String, String> = HashMap::new();
    for (key, value) in env::vars() {
        varsOut.insert(key, value);
    }

There is no problem to compile my code, just got error on console of the 2 platforms like this:
{"errorMessage":"unreachable","errorType":"RuntimeError","stackTrace":["at wasm-function[44]:273","at wasm-function[86]:39","at wasm-function[80]:40","at wasm-function[85]:41","at wasm-function[14]:882","at wasm-function[131]:5","at module.exports.hello (/var/task/wasm.js:184:20)","at Interface.emit (events.js:196:13)"]}

I think I can first get the variable by some nodejs code, then wrap the wasm, but is there any other way to get it by rust?

Thanks.