Configuring Gasket

All configuration of the Gasket plugins is centralized in a gasket.js file in the root of your application.

Presets and Plugins

To configure plugins in an app, update the plugins array in gasket.js with imported gasket plugin packages.

import pluginName from '@gasket/plugin-name';

export default makeGasket({
  plugins: [
    pluginName
    /* Plugins to add */ 
  ],
  // ...
});

Environments

The configuration system supports the concept of environments. An application will have certain configuration values that are not environment-specific and some, like service URLs, which are. Additionally, an environment may be subdivided further in other ways, for example distributed in multiple data centers, needing to use specific URLs for DC-local deployments of dependencies.

To augment the base gasket.js with environment-specific config, add an "environments" property to the config object, set to an object. Each key in this object should be an environment identifier, and each value is a configuration structure to deep merge into the base config. Use . in these keys to specify sub-environments. For example, here's a theoretical gasket.js:

export default makeGasket({
  someService: {
    enableSomeFeature: false
  },
  environments: {
    dev: {
      someService: {
        url: 'https://your-dev-service-endpoint.com'
      }
    },
    test: {
      someService: {
        url: 'https://your-test-service-endpoint.com'
      }
    },
    prod: {
      someService: {
        enableSomeFeature: true
      }
    },
    'prod.datacenter1': {
      someService: {
        url: 'https://your-datacenter1-prod-service-endpoint.com'
      }
    },
    'prod.datacenter2': {
      someService: {
        url: 'https://your-datacenter2-prod-service-endpoint.com'
      }
    }
  }
});

When accessing configuration in the prod.datacenter1 environment, the base configuration is augmented with the prod environment settings, then the prod.datacenter1 settings, resulting in:

{
  "someService": {
    "enableSomeFeature": true,
    "url": "https://your-datacenter1-prod-service-endpoint.com"
  }
}

The last step is making sure that Gasket is told which environment it is running in when starting up. To do so, set the GASKET_ENV environment variable. Alternatively, you can programmatically set an env property at the top level of your configuration, enabling you to use any arbitrary environment derivation logic.

Accessing Gasket configuration in your application

You can access the Gasket configuration in your application by importing the gasket object or through plugin hooks.

// example-plugin.js
export const name = 'example-plugin';

export const hooks = {
  express: async function (gasket, express) {
    console.log(gasket.config)
  }
};

export default { name, hooks };

// app-code.js

import gasket from './gasket.js';

console.log(gasket.config);

External configuration

Authoring a config plugin

If a config plugin does not yet exist for your configuration platform, writing one is straightforward. For Gasket-level configuration, hook the configure event. Your hook will be passed a config object, and you'll return an augmented config object.

// theoretical.js plugin
export default {
  name: 'theoretical',
  hooks: {
    configure(gasket, baseConfig) {
      const additionalConfig = addAdditionalConfig();
      return {
        ...baseConfig,
        ...additionalConfig
      };
    }
  }
}