Add in documentation that Node.js global vars may be kept between deployments

[paulbatum]

From @yvele on February 24, 2017 20:20

Specially usefull information when using Webpack to drastically reduce Azure Function cold start.

I understand the global vars sharing when I tried to use babel-polyfill and got this error:

Error: only one instance of babel-polyfill is allowed

Babel polyfill is using global vars and although I was importing it only once (in my webpack.config), I constantly get this error, and I finally had to make a little wrapper around my Azure Function handle to make sure babel-polyfill is not already loaded in global vars before requiring it.

I suggest adding a global vars warning in the documentation (especially with all Node.js developers going to make a webpack bundle to reduce Azure Function cold start.

This issue is kind of related to Azure/azure-functions-host#298 (comment) and attempts to make Azure Function work with Webpack.

Copied from original issue: Azure/azure-functions-host#1234

[paulbatum]

From @lindydonna on March 14, 2017 0:14

@christopheranderson @yochay Shouldn't this be moved to the Functions repo, since it's about documentation?

[paulbatum]

From @christopheranderson on April 3, 2017 17:17

@lindydonna - yes this should be moved

[paulbatum]

From @lindydonna on April 3, 2017 19:35

@christopheranderson Could you file a new issue in the docs repo to track this? You have more context on the doc requirement.

[nevercast]

@yvele What was your workaround for this?
Edit: I went with this in the end, should anyone else stumble here: https://gist.github.com/nevercast/e62157ccf385a9f22d1f68ec04274a5b

[ColbyTresness]

@mhoeger thoughts here?

[mhoeger]

I'm a bit confused, I'm suspicious that this is a functions issue? babel/babel-loader#401

I think it would be good though to add that global state is global for the function app (not per function), but there are no guarantees about preserved state of a global var (alluded to here)

[ColbyTresness]

I'm comfortable closing then. Please repoen if the doc Marie referenced is insufficient.