Node packages should not be fetched

[arichiardi]

Hello all!

I am trying the following in my script:

import * as fs from "fs"
...

but I receive:

ERRO[0000] GoError: Get https://fs?_k6=1: dial tcp: lookup fs on 127.0.0.11:53: no such host

It seems to me that the feature (I was reading issue #167) that fetches dependencies should skip fetching node built-in modules, but I might be doing something wrong instead.

Thanks for this, it looks very nice!

[arichiardi]

I have also some debug logs, and it seems my theory is not that far from reality:

DEBU[0000] Loading...                                    name=/scripts/k6sendEvent.js pwd=/go/src/github.com/loadimpact/k6
DEBU[0000] Resolved...                                   name=/scripts/k6sendEvent.js
DEBU[0000] Babel: Transformed                            t=128.073014ms
DEBU[0000] Loading...                                    name=fs pwd=/scripts
DEBU[0000] Resolved...                                   name=fs
DEBU[0000] Fetching source...                            url="https://fs?_k6=1"
DEBU[0000] Fetching source...                            url="https://fs"
ERRO[0000] GoError: Get https://fs?_k6=1: dial tcp: lookup fs on 127.0.0.11:53: no such host

[arichiardi]

There is a node package package that seems to have a list of built-in modules.

[ppcano]

k6 cannot load NodeJS API, because it does not run in NodeJS. k6 is written in go and use a JS interpreter to execute JS code.

Although you cannot import NodeJS API, you may use npm modules as described in the k6 Modules documentation.

If you want to open a file, you can use the open method, which given a file or a URL will return its contents. You have to call open outside the default function to avoid opening the file for each VU iteration.

import http from "k6/http";

const data = JSON.parse(open("./data.json"));

export default function() {
  let formData = ...;
  let res = http.post("https://httpbin.org/post", formData);
}

[arichiardi]

Oh wow got it!

Where is open coming from? What if a dependency uses node calls?

May I ask you the why of mixing the two worlds? In terms of usability it does seem a bit confusing I have to say. Or maybe I did not read the docs properly and this was written all along. In any case thanks a lot for the prompt response!

[ppcano]

Where is open coming from?

Sorry for that, there is a documentation article pending of being published.

What if a dependency uses node calls?

The Modules documentation describes that you have to browserify the npm module. Browserify will take care of the node calls.

May I ask you the why of mixing the two worlds?

JS as the scripting language for user adoption and go to achieve a decent performance.
You could read about k6 performance in this Performance comparison of Load testing tools

In terms of usability it does seem a bit confusing

I think we have to improve our documentation/communication in this aspect.

Thanks for the feedback.

I am closing the issue, let us know if you have any other question here or in stackoverflow using k6 tag

[arichiardi]

@ppcano I tried open but still does not find the file, is it a wrapper or straight go?

const data = JSON.parse(open("./events.json"));

time="2017-11-14T20:33:13Z" level=error msg="GoError: Get htt: lookup events.json on *my-ip-address:port:* no such host"