Overview

This simple Node.JS app comes with built-in "feature" behaviors - meaning - if you launch the app and tell it to run as feature 1, 2, 3 to show slightly different behavior. The web UI will change colors based on the enabled feature.

Feature	Behavior	Color
1	Everything good	Green
2	50% Failure Rate of /api/invoke	Red
3	Higher response times all requests	Yellow

Dynatrace

The demo app will put into the response a header called FeatureNumber. With this, a Dynatrace request attribute

Shown below is the setup for Dynatrace request attributes.

Dynatrace request attributes then allow the Custom multidimensional analysis.

Features

The application uses a default image of img/banner.png. This can be overwritten by setting the BANNER_IMAGE environment variable to a file in the img folder or using a URL.

Development

1. You must have node installed locally.

2. Once you clone the repo, you need to run npm install to download the required modules. I used npm: '8.x', node: '16.x'

   # set environment variables, for example
   export BANNER_IMAGE=img/banner.png
   
   # only set if using LaunchDarkly
   export FEATURE_FLAG_PROVIDER=launchdarkly
   export FEATURE_FLAG_SDK_KEY=[your key]
   
   # update packages
   npm update
   
   # start app
   npm start
   

   Access the application @ http://localhost:8080/

Build and Run

1. You must have Docker and Docker compose installed

2. Edit the environment variables values in the docker-compose.yaml file

3. If using feature flags, then export the SDK Key read by the docker-compose.yaml file

   export FEATURE_FLAG_SDK_KEY=[your sdk key]
   

4. Build and run Docker image manually. Run the buildrun.sh and buildpush.sh scripts.

LaunchDarkly Setup

To use LaunchDarkly, then the following are required:

1. Under LaunchDarkly settings, add project and save the SDK Key
2. Add a Feature flag called demoapp-feature as shown below
3. Add environment variables locally or in docker-compose.yaml file set

   export FEATURE_FLAG_PROVIDER=launchdarkly
   export FEATURE_FLAG_SDK_KEY=[your sdk key]