Simplify our "advanced" proxy

I think we made a mistake when we added advanced proxy configuration in 1.x.

It’s poor DX imo, and has caused numerous issues (I’m too lazy to search for them 😝). I mean look at this monstrosity. Yuck!

Note: this is not an attack against the contributor of this change. We are very grateful for the contribution and it has served us well. 😄

I propose we support the simplest of configurations:

1. Our default, simple behavior which works for many cases:

     "proxy": "http://localhost:4000",
   

2. An advanced case, which uses globs and proxies in 100% of cases (no heuristic):

     "proxy": [
       { "match": ["api/**/*", "!api/ws/*"], "target": "http://localhost:4000" },
       { "match": "api/ws/*", "target": "ws://localhost:4000" },
       { "match": "api2/**/*", "target": "http://localhost:4001" }
     ]
   

   or

     "proxy": [
       [["api/**/*", "!api/ws/*"], "http://localhost:4000"],
       ["api/ws/*", "ws://localhost:4000"],
       ["api2/**/*", "http://localhost:4001"]
     ]
   

In the “advanced” case, we don’t need to set ssl – check for https:// over http://. We don’t need to set ws, check for ws://; etc. Other features (e.g. url rewrites) should never happen at the client layer because this doesn’t translate to production (it’s leaky domain logic).

Thoughts?

We can add some code to auto-migrate old usage and remove it in v3.

[snardone]

@Timer, the new approach looks good but I have one request based on issues we’ve run into with our team. It would be helpful if the target value could be configurable outside of package.json.

In our environment, developers can test against the back-end running locally, or against a VM, or against a cloud server. So they modify their package.json accordingly, which gets accidentally checked it, which leads to conflicts, etc.

One solution might be to support environment variables in the target, for example:

"proxy": [
    { "match": ["api/**/*", "!api/ws/*"], "target": "http://${PROXY_HOST}" },
    { "match": "api/ws/*", "target": "ws://${PROXY_HOST}" },
    { "match": "api2/**/*", "target": "http://${PROXY2_HOST}" }
  ]

Thanks!

[maxhallinan]

@gaearon asked me to continue #3204 on this issue. To summarize:

• Proxy configuration is part of package.json.
• package.json is usually (maybe always) under source control.
• The location of a proxy target can vary with the environment.
• Because the proxy configuration is under source control, the location of the proxy target must be aligned across environments.
• Thus, it would be nice to move proxy configuration to the environment.