Dynamically-loadable drivers

[GochoMugo]

Since there may be numerous drivers in the wild, and the average user may not use most of the drivers, we need a way to only install and load the drivers the user is only interested in.

[GochoMugo]

Dynamic-loadable drivers can be installed using npm. For example,

$ npm install fpush-ssh-driver

Then to use the newly-installed driver, we can pass the CLI flag --dynamic-driver <driver>. For example,

$ fpush --dynamic-driver fpush-ssh-driver

The value passed (through dynamicDriver option in the API), is passed to require(), with the return value expected to be an object, with Driver property assigned to the Driver's class. For example,

// ... snip ...

try {
    const dynamicDriver = require('fpush-ssh-driver');
    typeof dynamicDriver === "object"; // true
    typeof dynamicDriver.Driver === "function"; // true; the class constructor
} catch (ex) {
    // ... snip ...
}

Note: we are using an object, instead of returning the constructor from require(), to allow future additions to the drivers, without breaking the API.

[GochoMugo]

As agreed above (... future additions ...), we can add properties to the driver interface.

A driver must export .protocol property key, purposefully for accessing configurations for the driver. Examples include "ftp", "sftp", etc.