Options will be passed as ENV_variables from command line

[openmohan]

Fixes: 613
The options sent from cli flags will also be saved as environment variables .

So they can be easily accessed as __ENV.XXXX

eg:
Running
./k6 run --vus 1 --iterations 1 --blacklist-ip 192.168.1.2/8,192.178.12.1/16 --duration 1s --summary-trend-stats "avg,p(95)" --system-tags check,group --tag test=p,l=0 --stage 5s:10,5m:20,10s:5 /media/sf_MCMP/Code/src/github.com/loadimpact/k6/test.js

test.js

export default function() {
    console.log("---START---")
    console.log("VUS" + __ENV.vus)
    console.log("duration" + __ENV.duration)
    console.log("stages" + __ENV.stages)
    console.log("throw" + __ENV.throw)
    console.log("systemTags" + __ENV.systemTags)
    console.log("blackListIPS" + __ENV.blacklistIPs)
    console.log("tags" + __ENV.tags)
    console.log("---END---")
}

Output:

INFO[0002] Setup done
INFO[0004] ---START---
INFO[0004] VUS1
INFO[0004] duration1s
INFO[0004] stages[{"duration":"5s","target":10},{"duration":"5m0s","target":20},{"duration":"10s","target":5}]
INFO[0004] throwfalse
INFO[0004] systemTags{"check":true,"group":true}
INFO[0004] blackListIPS["192.0.0.0/8","192.178.0.0/16"]
INFO[0004] tags{"l":"0","test":"p"}
INFO[0004] ---END---
INFO[0004] tear down done

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[codecov-io]

Codecov Report

Merging #681 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #681      +/-   ##
==========================================
+ Coverage   64.38%   64.38%   +<.01%     
==========================================
  Files         101      101              
  Lines        8274     8275       +1     
==========================================
+ Hits         5327     5328       +1     
  Misses       2598     2598              
  Partials      349      349

Impacted Files	Coverage Δ
lib/options.go	84.5% <ø> (ø)	⬆️
js/runner.go	78.92% <100%> (+0.1%)	⬆️

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[na--]

Thank you for trying to fix this issue, unfortunately I don't think this approach is the best way to go about it. I think that instead of exposing the final consolidated options as environment variables, we would be better off if we reuse the exported options variable and just update the final values there.

Also, in your code you're just parsing the CLI flags, while options can also be set via a config file, the exported script options and via environment variables. We already have a single struct in the Go code that has the consolidated option values from all of those possible sources and we just have to export it back to the scripts.

[openmohan]

Thanks for helping @na-- .
I have doubt here.
I understand the options variable has to be exported back to scripts but how they should be exposed in scripts. ie: how the real values can be read .
is that via module.exports or
any new export key like rt.Set("__OPTIONS", OPTIONS)
or any other better way

[na--]

I'm not completely sure, because goja (the JS runtime k6 uses) is a bit complex, but I think we can safely reuse/overwrite the original options variable, i.e. something like rt.Set("options", runner.GetOptions()). This seems like a good place to inject back the consolidated options.

[openmohan]

@na-- I have updated my commit , Please check it

[na--]

Looks much better, thanks!

As noted in the inline comment, I'm not sure that the purpose of the js struct tags in lib.Options is, I don't think that they are used by anything.

Also, it would be very useful if you write a unit test that checks this change before we merge it. Something like the tests here that checks if the javascript code would receive the options that were set by r.SetOptions(). For example, you can have setupTimeout: "1s" in the exported in-script settings and overwrite it with 3s from the outside and throw an exception if the script if the time setup timeout is still 1 second or something like that.

[na--]

What are the js: struct tags used for?

[openmohan]

here
when a struct is exported in to goja runtime, the property names are converted to snake_cased if "js" tag is missing in the struct
ie: VUs -> v_us , VUsMax -> v_us_max

[na--]

Ah, I see, makes total sense.

[na--]

Thanks for the test and for squashing the code! I'm merging this and later I'll probably expand the test slightly to also verify that the JS code sees the new options as well