support PORT environment variable

[cheslip]

This enables the use of a PORT environment variable that is commonly used with PaaS services such as Heroku and Cloud Foundry. Still defaults to 3000 if the env var is not set.

[albinekb]

Add it to the readme too? @cheslip 🎉

[timneutkens]

@leo @rauchg This one can be merged after the proposed change. Will this have any negative effect? I can imagine people having PORT defined and using micro index.js. Though that might be an edge case 🤔

[timneutkens]

Looks good 👍

[timneutkens]

I would turn PORT into PORT (wrap it in '`')

[rauchg]

Why not micro -p $PORT? Not being explicit about it is somewhat strange

[cheslip]

If done that way it won't default back to 3000 if $PORT isn't set which is useful for testing locally. On the other hand you could just do PORT=<port> micro -p $PORT so just a matter of preference.

[timneutkens]

@rauchg @cheslip Ah, I thought it was related to Heroku and Cloud Foundry not being able to do -p 😅 micro -p $PORT avoids weird bugs 👍

[rauchg]

@cheslip in that case we should make sure we default to 3000 if -p is supplied with no arguments or empty ones?

[timneutkens]

@rauchg I'll have a look into that 👍

[cheslip]

yes that should achieve similar behavior, thanks for looking into it