Merge pull request #14 from launchdarkly/lc/update-based-on-spec

fix: Update hello app and README according to new spec. Add CODEOWNERS

Author: louis-launchdarkly

CODEOWNERS

@@ -0,0 +1,2 @@
+# Repository Maintainers
+* @launchdarkly/team-sdk-js

README.md

@@ -1,23 +1,24 @@
 # LaunchDarkly sample Node.js (server-side) application
 
-We've built a simple console application that demonstrates how LaunchDarkly's SDK works. 
Below, you'll find the build procedure. For more comprehensive instructions, you can visit your [Quickstart page](https://app.launchdarkly.com/quickstart#/) or the [Node.js (server-side) reference guide](https://docs.launchdarkly.com/sdk/server-side/node-js).
+We've built a simple console application that demonstrates how LaunchDarkly's SDK works.
+
+Below, you'll find the build procedure. For more comprehensive instructions, you can visit your [Quickstart page](https://app.launchdarkly.com/quickstart#/) or the [Node.js (server-side) reference guide](https://docs.launchdarkly.com/sdk/server-side/node-js).
 
 The LaunchDarkly server-side SDK for Node.js is designed primarily for use in multi-user systems such as web servers and applications. It follows the server-side LaunchDarkly model for multi-user contexts. It is not intended for use in desktop and embedded systems applications.
 
 For a sample application demonstrating how to use LaunchDarkly in *client-side* Node.js applications, refer to our [Client-side Node.js SDK sample application](https://github.com/launchdarkly/hello-node-client).
 
 ## Build instructions
 
-1. Install the LaunchDarkly Node.js SDK by running `npm install`
-
-2. Edit `index.js` and set the value of `sdkKey` to your LaunchDarkly SDK key. If there is an existing boolean feature flag in your LaunchDarkly project that you want to evaluate, set `featureFlagKey` to the flag key.
+1. Set the environment variable `LAUNCHDARKLY_SERVER_KEY` to your LaunchDarkly SDK key. If there is an existing boolean feature flag in your LaunchDarkly project that you want to evaluate, set `LAUNCHDARKLY_FLAG_KEY` to the flag key; otherwise, a boolean flag of `sample-feature` will be assumed.
 
-```js
- const sdkKey = "1234567890abcdef";
+ ```bash
+ export LAUNCHDARKLY_SERVER_KEY="1234567890abcdef"
+ export LAUNCHDARKLY_FLAG_KEY="my-boolean-flag"
+ ```
 
- const featureFlagKey = "my-flag";
-```
+2. Install the LaunchDarkly Node.js SDK by running `npm install`
 
 3. Run `node index.js`
 
-You should receive the message `"Feature flag '<flag key>' is <true/false> for this user"`.
+You should receive the message "The <flagKey> feature flag evaluates to <flagValue>.". The application will run continuously and react to the flag changes in LaunchDarkly.

index.js

@@ -1,18 +1,34 @@
-var LaunchDarkly = require('@launchdarkly/node-server-sdk');
+const LaunchDarkly = require('@launchdarkly/node-server-sdk');
 
 // Set sdkKey to your LaunchDarkly SDK key.
-const sdkKey = "";
+const sdkKey = process.env.LAUNCHDARKLY_SDK_KEY ?? 'your-sdk-key';
 
 // Set featureFlagKey to the feature flag key you want to evaluate.
-const featureFlagKey = "my-boolean-flag";
+const featureFlagKey = process.env.LAUNCHDARKLY_FLAG_KEY ?? 'sample-feature';
 
-function showMessage(s) {
- console.log("*** " + s);
- console.log("");
+function showBanner() {
+ console.log(
+ ` ██
+ ██
+ ████████
+ ███████
+██ LAUNCHDARKLY █
+ ███████
+ ████████
+ ██
+ ██
+`,
+ );
 }
 
-if (sdkKey == "") {
- showMessage("Please edit index.js to set sdkKey to your LaunchDarkly SDK key first");
+function printValueAndBanner(flagValue) {
+ console.log(`*** The '${featureFlagKey}' feature flag evaluates to ${flagValue}.`);
+
+ if (flagValue) showBanner();
+}
+
+if (!sdkKey) {
+ console.log('*** Please edit index.js to set sdkKey to your LaunchDarkly SDK key first.');
  process.exit(1);
 }
 
@@ -21,26 +37,30 @@ const ldClient = LaunchDarkly.init(sdkKey);
 // Set up the context properties. This context should appear on your LaunchDarkly contexts dashboard
 // soon after you run the demo.
 const context = {
- kind: "user",
- key: "example-context-key",
- name: "Sandy"
+ kind: 'user',
+ key: 'example-user-key',
+ name: 'Sandy',
 };
 
-ldClient.waitForInitialization().then(function () {
- showMessage("SDK successfully initialized!");
- ldClient.variation(featureFlagKey, context, false, function (err, flagValue) {
- showMessage("Feature flag '" + featureFlagKey + "' is " + flagValue + " for this context");
-
- // Here we ensure that the SDK shuts down cleanly and has a chance to deliver analytics
- // events to LaunchDarkly before the program exits. If analytics events are not delivered,
- // the context properties and flag usage statistics will not appear on your dashboard. In a
- // normal long-running application, the SDK would continue running and events would be
- // delivered automatically in the background.
- ldClient.flush(function () {
- ldClient.close();
+ldClient
+ .waitForInitialization()
+ .then(() => {
+ console.log('*** SDK successfully initialized!');
+
+ const eventKey = `update:${featureFlagKey}`;
+ ldClient.on(eventKey, () => {
+ ldClient.variation(featureFlagKey, context, false).then(printValueAndBanner);
  });
+
+ ldClient.variation(featureFlagKey, context, false).then((flagValue) => {
+ printValueAndBanner(flagValue);
+
+ if(typeof process.env.CI !== "undefined") {
+ process.exit(0);
+ }
+ });
+ })
+ .catch((error) => {
+ console.log(`*** SDK failed to initialize: ${error}`);
+ process.exit(1);
  });
-}).catch(function (error) {
- showMessage("SDK failed to initialize: " + error);
- process.exit(1);
-});