Change env stringified so it doesn't overwrite process.env

[tgriesser]

I believe this is part of the confusion around env vars and #528

With the current code, webpack's DefinePlugin sees the process.env variable as predefined entirely, 'process.env': .... If the env value doesn't exist webpack then inlines the entire stringified value object in the generated code.

With this change, we define each process.env.$VAR individually, which means that unknown variables will be left alone at build time.

If you add this in server.js:

console.log(process.env.ITEMS)
console.log(process.env.NODE_ENV)

Current behavior:

console.log(Object({"NODE_ENV":"development","PORT":"3000","VERBOSE":false,"HOST":"localhost","RAZZLE_ASSETS_MANIFEST":"/home/razzle-example/build/assets.json","BUILD_TARGET":"server","PUBLIC_PATH":"/","RAZZLE_PUBLIC_DIR":"/home/razzle-example/public"}).ITEMS);
console.log("development")

With this change:

console.log(process.env.ITEMS)
console.log("development")

[jaredpalmer]

Awesome! This looks very very promising. I need to run some tests on our infrastructure to check this out.

[jaredpalmer]

Testing this out right meow.

[jaredpalmer]

LGTM

[tgriesser]

Awesome! Thanks!

[s123121]

Any idea when we can have this pull request as a stable release? I really need this now to configure CI