support YAML for app declaration

[rlidwka]

I'm looking at this, and just realizing that is not a meteor issue. It's pm2 issue. JSON just doesn't work quite right when used for config files.

If we add yaml support, @dandv 's example could be rewritten like this:

name: frontend
script: main.js

env:
  NODE_ENV: production
  METEOR_SETTINGS: |
    {
      "Kadira": {
         "appId": "...",
         "appSecret": "..."
      },
      "public": {
        "analytics_api_key": "xxx",
        ...
      }
    }

... solving all issues with escaping quotes.

I don't even mention that in production environments those files need to be commented out (which json doesn't support), or a handy feature of yaml that allows to define constants and reuse it anywhere in the same file (say, define "max_restarts" once and use that value for every app).

This would also remove the need for single quotes in "args" (and therefore eval(), see #568, which one could see as a possible security issue), replacing that with double quotes and a regular JSON.parse().

[dandv]

JSON is surprisingly bad for config files, yet it continues to be used.

[soyuka]

js is for me a better alternative than yaml but that's an endless debate.

I don't understand why this won't work:

"env": {
    "NODE_ENV": "production",
    "METEOR_SETTINGS": {
      "Kadira": {
         "appId": "...",
         "appSecret": "..."
      },
      "public": {
        "analytics_api_key": "xxx",
        ...
      }
    }

[rlidwka]

js is for me a better alternative than yaml

Since json is a subset of yaml, you can use json even inside yaml config. So it isn't really about an alternative, it is about opening a possibility for better config files for other people.

An alternative would be to use json5, it's basically a javascript syntax with json-only data. But what I like in yaml is something like this:

[{
  "name"      : "api",
  "script"    : "./api.js",
  "instances" : &instances 4,
  "env": &my_env {
    "NODE_ENV": "production",
    "AWESOME_SERVICE_API_TOKEN": "xxx",
  }
},{
  "name"      : "frontend",
  "script"    : "./frontend.js",
  "instances" : *instances,
  "max_restarts": &restarts 15,
  "env"       : *my_env,
},{
  "name"      : "backend",
  "script"    : "./backend.js",
  "max_restarts": *restarts,
  "instances" : *instances,
  "env"       : *my_env,
}]

This is a valid yaml document. Do you see what I've done here?

If you have multiple applications in your services.json file, a lot of information would be duplicated. Say, instances or max_restarts could be different from the default, but the same for some of your apps.

With yaml one could create a constant somewhere in the file, and reuse it later in the same file. If we need to change a constant (say, API tokens are changed frequently), in JSON you would have to replace it in dozen places, but with this configuration you can do it just once.

YAML ain't ideal, but in the case of pm2 it seems like the best fit.

[soyuka]

#248

Also we should require() instead of readFileSync here: https://github.com/Unitech/pm2/blob/master/lib/CLI.js#L230

So we might use pure js.

[rlidwka]

Pure js is a script format, not a data format, current "configuration" syntax won't work so nicely there.

If you want to use js, maybe add high-level syntax. Instead of:

{
  "name"      : "api",
  "script"    : "./examples/child.js",
  "instances" : "4",
  "error_file" : "./examples/child-err.log",
  "out_file" : "./examples/child-out.log"
}

Write something like:

require('pm2').create_app('api')
  .script('./examples/child.js')
  .instances(4)
  .error_file('./examples/child-err.log')
  .out_file('./examples/child-out.log')

Maybe it's already possible somehow.

[soyuka]

Nope it's only that you can require json files and so, you would be able to do a configuration like this:

module.exports = {
    scripts: 'test.js',
    instances: 4
}

[Unitech]

JSON5 support has been added, try the #development branch

[naggie]

Yaml support would still be nice. May I add it?

[jshkurti]

Sure :)

[Unitech]

Yes would be nice, @naggie do you know any lightweight yaml library for node? (without too many dependencies)

[soyuka]

@Unitech @naggie I'm using https://www.npmjs.com/package/yamljs

[michaelBenin]

I would like to +1000 this. I like having comments in my configuration file.

[naggie]

Great, I'll do it this evening. @michaelBenin BTW I think you can put in comments anyway with the current JSON5 support: http://json5.org/. Nonetheless, YAML files are nicer for humans to read/write; also allowing anchors & references.

[naggie]

I have 2 options:

1. Drop JSON5 support in favour of YAML and risk the PR not being accepted. Bear in mind that JSON is a subset of YAML so we can still use JSON files; even commented JSON files
2. Change parser by file extension. This might not be straightforward as files are loaded into strings and passed around in CLI.js sometimes.

I would prefer option (1)

N.B. I noticed a few instances that might not work with the JSON5 parser -- a filename is given instead of the string

[soyuka]

You can also test the first character of the string that's not a space or a
new line. If it's { or [ it's json if not it's yaml. Solution one, will
indeed bring a compatibility issue and therefore won't be merged...
If a file is sent as an argument testing the file extension seem fair to me.
Le mar. 31 mars 2015 à 10:20, Callan Bryant notifications@github.com a
écrit :

I have 2 options:

1. Drop JSON5 support in favour of YAML and risk the PR not being
   accepted. Bear in mind that JSON is a subset of YAML so we can still use
   JSON files; even commented JSON files
2. Change parser by file extension. This might not be straightforward
   as files are loaded into strings and passed around in CLI.js sometimes.

I would prefer option (1)

N.B. I noticed a few instances that might not work with the JSON5 parser
-- a filename is given instead of the string

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Reply to this email directly or view it on GitHub
#578 (comment).

[felixfbecker]

I also think PM2 should accept multiple file types for app declarations. _It currently supports embedding JS inside JSON!_ If you write Javascript inside a "JavaScript Object Notation" file you might as well just put in a JS file with module.exports =. PM2 should accept .yaml, .json and .js.
JSON really is bad without official support for comments and all the quoting going on.

[Unitech]

Feature landed in development branch, thanks to the lightweight YAML parsing module https://www.npmjs.com/package/yamljs

[Unitech]

Update available (PM2@1.1.1 - latest stable):

$ npm install pm2@latest -g
$ pm2 update

Please re-open this issue if you notice any problem,