Slack Appender for log4js-node

Sends log events to a slack channel. This is an optional appender for use with log4js.
``bash
npm install @log4js-node/slack
`

Configuration

* type - @log4js-node/slack
* token - string - your Slack API token (see the slack and slack-node docs)
* channel_id - string - the channel to send log messages
* icon_url - string (optional) - the icon to use for the message
* username - string - the username to display with the message
* layout - object (optional, defaults to basicLayout) - the layout to use for the message (see layouts).

Example

`javascript
log4js.configure({
appenders: {
alerts: {
type: '@log4js-node/slack',
token: 'abc123def',
channel_id: 'prod-alerts',
username: 'our_application'
}
},
categories: {
default: { appenders: ['alerts'], level: 'error' }
}
});
`
This configuration will send all error (and above) messages to the prod-alerts slack channel, with the username our_application`.