Merge rewrite rules from multiple .local-web-server.json files

[djKianoosh]

If we have two .local-web-server.json files, say in the current directory and in the user's $HOME, configurations like port get merged properly, but if both files have rewrite rules, then only the rules in the current directory show up with ws --config.

Maybe it needs a deep merge?

[75lb]

hi @djKianoosh .. yes, a deep merge would fix this issue in your case but this behaviour would sometimes be undesirable..

typically, a user puts their default config in $HOME.. later, if they decide to add some config within the project folder they typically want this config to override the $HOME config, not extend it..

leaving ticket open for further suggestions.. ideally, we could choose whether project config merges with or overrides $HOME config.

[djKianoosh]

Yeah, maybe a separate config that controls whether to override completely or merge would help there.

For our use case, which is sort of a custom microservice environment, we could have several projects that would like to extend a base config (port, and a base rewrite rule to our dev server). Then, depending on what project a developer is working on, that project would override the the rewrite rule to hit a local api server for that particular api they are working on. Make sense?

[djKianoosh]

@75lb let me know how I can help, if you need a PR or example configs. I tried to find where in the code to make this change but got lost in the weeds a little bit. If you can point me in the right direction I may be able to help.

[djKianoosh]

Mainly looking at https://github.com/75lb/local-web-server/blob/master/bin/cli.js#L133 Where you're using Object.assign http://www.2ality.com/2014/01/object-assign.html

The question is what deep merge function would you prefer to use? Lodash's or a custom one like in http://stackoverflow.com/questions/27936772/deep-object-merging-in-es6-es7

And then what do you want to call the option to bypass the normal extend vs doing the deep merge?

[djKianoosh]

I think I see the loading up of configs is actually done in your config-master lib: https://github.com/75lb/config-master/blob/master/lib/config-master.js#L29

[djKianoosh]

I made a pr in that repo to add a deep merge option: https://github.com/75lb/config-master/pull/2

[75lb]

hi, thanks for the PR - i will take a look tonight after work and Parent's Evening 👍

[75lb]

i have released this feature on a tag as it needs testing.. please install and let me know your thoughts:

$ npm install -g local-web-server@deep

then run it with this flag:

$ ws --deep-merge-config

see the config master deep branch to see the changes.

[djKianoosh]

So I did a super quick dirty example to see it in action with that flag. It's here: https://github.com/djKianoosh/local-web-server-deep-merge-example

When I run it inside the subdir I get the following rules:

  "rewrite": [
    {
      "from": "one",
      "to": "two"
    },
    {
      "from": "two",
      "to": "three"
    }

Are those valid rewrite rules? Shouldn't it be something like:

  "rewrite": [
    {
      "from": "two",
      "to": "three"
    }

For reference, the .local-web-server.json in the parent dir looks like:

{
  "port": 8888,
  "rewrite": [
     { "from": "one", "to": "two" }
  ]
}

and the one in the subdir looks like:

{
  "rewrite": [
    { "from": "two", "to": "three" }
  ]
}

[djKianoosh]

I see what you mean. You have it right. I had to look again at the example you provided in https://runkit.com/75lb/58066f28868d5c0014804c73

[75lb]

so is it working correctly now in your real life case?

[djKianoosh]

Actually the order of precedence matters. So we want the rewrite rules in the local directory to be more important/specific than the ones in the parent directories. I'm thinking you can either reverse the order that you're doing them now, or add some numeric precedence in the rewrite rule object to sort by (more complicated, granted).

[75lb]

i avoid deep merging in all my tools (it's an opinionated area with different strategies to suit different scenarios) but in the specific case of rewrite rules, i think the behaviour you described would be the appropriate default..

i will look into reversing the order of precedence tonight, to make your local settings higher priority..

[djKianoosh]

thanks @75lb you're the man

[75lb]

this is resolved in v2 which is in progress and available for preview. Config files are now plain javascipt, giving you freedom to share and merge options however you like.

The config file (lws.config.js by default) should look something like this:

module.exports = {
  rewrite: [
    {
      from: '/resources/*',
      to: 'http://remote-api.org:8080/resources/$1'
    }
  ],
  directory: 'src',
  'log.format': 'none'
}

An example of how you might share and merge options:

/* pull options from the env */
const remoteAPI = process.env.REMOTE_API

/* .. or an installed package */
const sharedOptions = require('shared-options')

/* merge them to taste */
const options = Object.assign({}, sharedOptions, {
  rewrite: [
    {
      from: '/resources/*',
      to: `http://${remoteAPI}/resources/$1`
    }
  ]
})

module.exports = options

[75lb]

fixed and released in v2.0.0

[djKianoosh]

Thanks and congrats on the release!

Here's another way to do what I was trying to do, which is have a default config in user home, with local rewrite rules (in a given project for example) taking precedence:

In ~/project/lws.config.js :

const options = require(require('os').homedir() + '/lws.config.js');

options.rewrite.unshift({
    from: '/base/higher/precedence/*',
    to: 'http://localhost:8080/base/higher/precedence/$1'
});

module.exports = options;

Using .unshift() just to put the item to the front of the array as opposed to .concat().

And in ~/lws.config.js:

module.exports = {
  port: 80,
  rewrite: [
    {
      from: "/base/*",
      to: "https://internal/base/$1"
    }
  ]
}

Results in the following with version 2.0.1:

$ ws --config
{ port: 80,
  stack:
   Stack [
     BodyParser,
     RequestMonitor,
     Log,
     Cors,
     Json,
     Rewrite,
     Blacklist,
     ConditionalGet,
     Mime,
     Compress,
     MockResponse,
     SPA,
     Static,
     Index ],
  rewrite:
   [ { from: '/base/higher/precedence/*',
       to: 'http://localhost:8080/base/higher/precedence/$1' },
     { from: '/base/*', to: 'https://internal/base/$1' } ],
  config: true }

[75lb]

looks good, thanks for confirming you got it working! i will write a tutorial on how to share rewrite rules at some point 👍