prefab-cloud-nodejs

Prefab Node.js client

Install the client

npm install @prefab-cloud/prefab-cloud-node or yarn add @prefab-cloud/prefab-cloud-node

Set up a Prefab client.

import { Prefab } from "@prefab-cloud/prefab-cloud-node";

if (!process.env.PREFAB_API_KEY) {
  throw new Error("PREFAB_API_KEY is not set");
}

const prefab = new Prefab({
  apiKey: process.env.PREFAB_API_KEY,
  enableSSE: true,
  enablePolling: true,
});

await prefab.init();

After the init completes you can use

• prefab.get('some.config.name') returns a raw value
• prefab.isFeatureEnabled('some.feature.name') returns true or false
• prefab.shouldLog({loggerName, desiredLevel, defaultLevel, contexts}) returns true or false

Prefab supports context for intelligent rule-based evaluation of get and isFeatureEnabled based on the current request/device/user/etc.

Given

const context = new Map([
  [
    "user",
    new Map([
      ["key", "some-unique-identifier"],
      ["country", "US"],
    ]),
  ],

  [
    "subscription",
    new Map([
      ["key", "pro-sub"],
      ["plan", "pro"],
    ]),
  ],
]);

You can pass this in to each call

• prefab.get('some.config.name', context, defaultValue)
• prefab.isFeatureEnabled('some.feature.name', context, false)

Or you can set the context in a block (perhaps surrounding evaluation of a web request)

prefab.inContext(context, (pf) => {
  const optionalJustInTimeContext = { ... }

  console.log(pf.get("some.config.name", optionalJustInTimeContext, defaultValue))
  console.log(pf.isEnabled("some.config.name", optionalJustInTimeContext, false))
})

Note that you can also provide Context as an object instead of a Map, e.g.:

{
  user: {
    key: "some-unique-identifier",
    country: "US"
  },
  subscription: {
    key: "pro-sub",
    plan: "pro"
  }
}

Option Definitions

Besides apiKey, you can initialize new Prefab(...) with the following options

| Name | Description | Default | | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------- | ----------------- | | collectEvaluationSummaries | Send counts of config/flag evaluation results back to Prefab to view in web app | true | | collectLoggerCounts | Send counts of logger usage back to Prefab to power log-levels configuration screen | true | | contextUploadMode | Upload either context "shapes" (the names and data types your app uses in prefab contexts) or periodically send full example contexts | "periodicExample" | | defaultLevel | Level to be used as the min-verbosity for a loggerPath if no value is configured in Prefab | "warn" | | enableSSE | Whether or not we should listen for live changes from Prefab | true | | enablePolling | Whether or not we should poll for changes from Prefab | false |