@modus/gimbal-plugin-last-value

Gimbal last-value Plugin

The last-value plugin adds past value retrieval and saving to Gimbal audits. This plugin adds a new column to the output to show the last value and whether the current value has changed over a threshold.

Installation

First, you need to install the plugin to your project:

# with npm
npm install --save-dev @modus/gimbal-plugin-last-value

# or with yarn
yarn add --dev @modus/gimbal-plugin-last-value

Next, you need to add the plugin to your Gimbal configuration file:

YAML

plugins:
  - '@modus/gimbal-plugin-last-value'

JSON

{
  "plugins": ["@modus/gimbal-plugin-last-value"]
}

JavaScript

modules.exports = {
  plugins: ['@modus/gimbal-plugin-last-value'],
};

Configuration

There are three configs that you can change:

• failOnBreach - Defaults to false to allow the plugin to warn of a size change instead of failing on the change. Set to true to fail the Gimbal audit run when the current value breaches the threshold of the last value.
• saveOnlyOnSuccess - Defaults to true to only save the current value to the storage (e.g. MySQL) on a successful Gimbal audit run. Set to false to always save the current value to the storage.
• threshold - This is the object of thresholds. Each module has a different type of value: number, percentage, or size.

Threshold

As mentioned, thresholds can be described for the three different types of module values:

• The number type is the simplest where the number is just a number or a score. The lighthouse module uses numbers as scores.
• The percentage type is percentage based being from 0% to 100%. The unused-source module uses percentages to show how much of a file is unused.
• The size type is for file and directory sizes in bytes. The threshold can describe thresholds for each type. The heap-snapshot and size modules show file and directory sizes.

There may be times where the difference of the last value and the current value is within the threshold that may still need to be fail. For this, there is a diffPercentage value. This allows the difference to be checked against the last value to see if the difference is more than a percentage of the last value. So if the last value is 100, the difference was 2 this means the diff percentage is 2% and while that 2 may be under the threshold, it may be more than you want to allow through without some sort of warning or even a failure.

Default Configuration

plugins:
  - plugin: "@modus/gimbal-plugin-last-value"
  failOnBreak: false
  saveOnlyOnSuccess: true
  threshold:
    diffPercentage: 2
    number: 1
    percentage: 1
    size: 1000

Storage

This plugin only does calculation on the Gimbal audit run, the data for the last value needs to come from another plugin. Gimbal has some plugins available but you can provide your own as well.

• mysql
• sqlite

This plugin expects an array of rows in this format:

[
  {
    "command": "audit",
    "date": "2019-01-01 01:00:00",
    "audit": "{...}"
  }
]

The date field isn't needed by this plugin but is a good way for the storage plugin to be able to get the last run. The command field allows for some segregation of reports in case you run different commands. This would be like audit or size and is the same as if you executed gimbal audit on the command line. The audit field is a JSON blob that is the raw Gimbal audit report. If the audit field is a string, this plugin will attempt to JSON.parse() the value to get the JavaScript object.

This plugin will fire two events to get and save last value reports. The plugin would need to listen to them to support this plugin:

module.exports = async ({ bus }, pluginConfig) => {
  const event = await bus('event');

  event.on('plugin/last-value/report/get', (eventName, { command }) => getLastValue(command));

  event.on('plugin/last-value/report/save', (eventName, { command, report }) => saveLastValue(command, report));
};