Quickstart: Node, Bun and Deno

This quickstart creates an environment, a flag and a server key, then evaluates the flag from a script with OpenFeature and EZGH’s server provider.

Before you start

• Node.js 20 or later, Bun or Deno.
• The ezgh CLI (install it), logged in, with a project selected (--project or EZGH_PROJECT), and FlagsFullAccess on it (or the root user).

1. Create an environment, a flag and a key

ezgh flags envs create production
ezgh flags create new-checkout --name "New checkout"
ezgh flags toggle new-checkout --env production --on
export EZGH_FLAGS_SDK_KEY=$(ezgh flags keys create --env production --kind server --name quickstart)

The flag is a boolean: on, with no rules, it serves true to everyone (its default rule). The key is printed once.

2. Install

The provider isn’t published to npm yet: install it from GitHub by tag, with OpenFeature’s server SDK.

npm install @openfeature/server-sdk github:ezgamehost/flags-provider-ts#v0.1.0

3. Evaluate

import { OpenFeature } from "@openfeature/server-sdk"
import { EzghProvider } from "@ezgh/flags-openfeature/server"

await OpenFeature.setProviderAndWait(new EzghProvider({ sdkKey: process.env.EZGH_FLAGS_SDK_KEY! }))
const flags = OpenFeature.getClient()

const details = await flags.getBooleanDetails("new-checkout", false, { targetingKey: "user-1842", plan: "free" })
console.log(details.value, details.reason)

Run it with node flags.ts (Node 22.18 or later), bun flags.ts or deno run -A flags.ts. It prints true STATIC.

4. Change the targeting

Keep the new checkout from the free plan, then evaluate again:

ezgh flags config get new-checkout --env production > checkout.json

Add a rule to checkout.json’s rules:

{ "id": "0199a3c2-7a10-7c11-9b01-1f2e3d4c5b6a", "description": "Free plan", "clauses": [{ "attribute": "plan", "operator": "in", "values": ["free"] }], "serve": { "variation": "false" } }

ezgh flags config set new-checkout --env production --file checkout.json

The script now prints false TARGETING_MATCH; a context with another plan still gets true (reason DEFAULT). A long-running process gets the change within seconds, without restarting.

How the server provider works

• It downloads the environment’s flags when it starts, and is ready once they’re loaded. Then it follows a stream of changes; if the stream fails it reads the flags every 30 seconds while it reconnects.
• Evaluation is local: no network call per evaluation.
• On a change it emits PROVIDER_CONFIGURATION_CHANGED with the keys of the flags that changed. While it’s disconnected it keeps evaluating the last flags it had and emits PROVIDER_STALE.
• endpoint overrides https://flags.ezghcloud.com. bootstrapPath starts it from a file written by ezgh flags export; with offline: true it uses only that file (tests, CI).

new EzghProvider({ sdkKey, bootstrapPath: "flags.json", offline: true })