Add build-local.json check for local development

[mbarlow12]

We've hardcoded the address of a local development. @zepumph noted in #12 that this should be configurable for different environments. To allow for this, we'll add a check in ~/.phet/build-local.json for the following keys:

{
    "localHostURL": "http://localhost",
    "localHostPort": "8080"
}

Since node's http-server runs the server configured above, those will be the defaults.

• Add build-local.json check and defaults for setting the local dev server URL in getFromSimInMaster.js.
• Add config options to README

[zepumph]

This would be so very nice. I would also recommending loud asserts if those keys are not present when running.

[mbarlow12]

All that's left for this is to update the documentation. To generate the docs, binder looks in build-local.json for the following:

{
  "localhostURL": "https://someUrl",    // REQUIRED with asserts
  "localhostPort": "42"   // optional
}

It uses https://github.com/phetsims/perennial/blob/master/js/common/buildLocal.js to access the local configuration, so the getters have been added.

[samreid]

I don't mind adding localhostPort to my config, but I thought it would be nice to poll the development team to see how many people are using each port. Let's use this comment as the voting comment, with 👍 as 8080, 😆 as 80 and ❤️ as something else.

[jonathanolson]

I'm not sure why the URL and port are separated, since the port could be part of the URL. How do you plan to handle http://localhost:8080/something/? It seems like it would be easier (and fixes this issue) to have it be part of one URL.

[mbarlow12]

@jonathanolson That's true—I think that'd be a worthwhile change. It's just been a habit for a long time to separate the port.

[pixelzoom]

FYI, I'm using port 80 because it's the default for Apache on macOS. It can be configured in /etc/apache2/httpd.conf.

[mbarlow12]

@pixelzoom do you see problems arising from using a single key in build-local.json for both the host and port?

[pixelzoom]

I've been out of the loop wrt binder, so much so that I have no idea why a host and port are even needed. Try it and see?

[mbarlow12]

README updated. Closing.