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oconf

Configuration

OConf

Load cjson (JSON + c-style) commentaries, with inheritance-sugar on top:

> var oconf = require('oconf');
> oconf.load('config/my-config.cjson');
{
     "some-setting": "default-value",
     "value": 50
}

Anywhere in your cjson file, you can #include another cjson file. The file containing the #include directive overrides any values from the file being included, in case of conflicts.

The basic idea is to experiment with applying #include-directives recusively inside JSON/cJSON documents:

// default-settings.cjson 
{
    "some-setting": "default value",
    "value": 100
}
// my-config.cjson 
{
    "#include": "./default-settings.json",
    "value": 50
}

Will result in a config with:

{
    "some-setting": "default-value",
    "value": 50
}

The extension of objects also work recursively, so setting a single sub-key somewhere doesn't override the entire thing.

There are no restrictions in how includes work (except no loops). Usually a structure like this is used:

  • project/config/default.cjson has project-wide defaults.
  • project/config/{dev,test,staging,production}.cjson inherits the default and set keys relevant to respective environments
  • project/config/$HOSTNAME.cjson (optinal) machine-specifics that inherit from the relevant environment-file.
  • /etc/$WORKNAME/$PROJECTNAME-secrets.cjson inherits the machine-specific things and typically adds production secrets.

With this directive, you can generate a json blob that can be safely exposed to client-side code. This is useful when some properties on the same object are safe to expose to client code, while others are not.

In case of conflicts between a #public and a non-public key on the same object, an error is thrown - it is usually a sign that a new key needs to be introduced if the same key contains different values for client and server code.

The #include directives are processed before #public.

Anywhere in your cjson file, you can add a #public property to an object, denoting some keys on that property you want grouped together on the #public property of the root of your config.

// some-public-settings.cjson 
{
  "some-setting": "default value",
  "value": 100,
  "fancy-list": {
    "expose-foo": true,
    "#public": {
      "scroll-timeout": 100
    }
  }
}

Will result in a config with:

{
  "some-setting": "default-value",
  "value": 100,
  "fancy-list": {
    "expose-foo": true,
    "scroll-timeout": 100
  },
  "#public": {
    "fancy-list": {
      "scroll-timeout": 100
    }
  }
}

You can instruct oconf.load to only return configuration properties marked with #public:

> var oconf = require('oconf');
> oconf.load('config/some-public-settings.cjson', { public: true });
{
    "fancy-list": {
        "scroll-timeout": 100
    }
}

Of course you can also just grab the #public property from the result of oconf.load:

> var oconf = require('oconf');
> oconf.load('config/some-public-settings.cjson')['#public'];
{
    "fancy-list": {
        "scroll-timeout": 100
    }
}

To help resolve configuration on the command line oconf exports a CLI tool called oconf. It takes a path to an cjson file, and outputs the resolved JSON object.

 $ oconf config.cjson
{
  "someConfig": "someValue",
  "obj": {
    "foo": "bar"
  }
}

You can lint your configuration files by using the --lint flag. It will not output any of the resolved configuration, but only exit with an error in case of any formatting errors in the files.

 $ oconf --lint config.cjson

By using the --extract-option flag you can supply a path to a value as well:

 $ oconf --extract-option obj.foo config.cjson
bar

The output from the above is the raw data. That is useful when you need to pass the configuration to other CLI tools. If you need the JSON formatted data, you can pass the --option-as-json option.

 $ oconf --extract-option obj.foo --json config.cjson
"bar"

If the key is missing oconf --extract-option will exit with status code 1. If you need to overwrite that behaviour you can pass the --allow-missing-option flag to oconf which will make it exit with status code 0 if no value is found at the given path.

You can also filter out values in the #public blob with the --public flag.

 $ oconf --public some-public-settings.cjson
{
  "fancy-list": {
    "scroll-timeout": 100
  }
}

Download/clone, run npm install and then npm test.

The software is provided under the Modified BSD License; See LICENSE for further details.