LaunchDarkly Homework - Osborn

LD sample project to demonstrate some capabilities, complete the assignment, and have some fun.

Table of Contents

• Framework Description
• Olympic Results App
  • User Accounts
• Using the App
  • Local Configuration
  • Run the Application
  • Notes
• Technical Exercises
  • Part 1: Release and Remediate
  • Part 2: Target
  • Extra Credit: Experimentation
  • Extra Credit: Integrations

Framework Description

I chose the following framework and tools for this application primarily because they can get you started in just a few minutes.

• I did the work on a mac and using brew to install java 21 and gradle
• I used IntelliJ as an IDE but, of course, you can use whatever you like
• Spring Boot Initalizr is so great to just download and go so that's what I did
• I pickedvue.js as the front end because it can be run directly in the browser (without transpiler) and is enough to get this work done
• The data and authentication are both in-memory implementations for simplicity
• The default output from the ldcli is a string and I use iTerm2 so I pipe the results through jq to format the output
• I apologize ahead of time for the keys and passwords pushed to git (gulp)

Olympic Results App

I built a simple application that displays Olympic Medal data. Since the Olympics are super relevant at the moment, customers are clicking more and more on the table. We've heard complaints of slowness. We believe the slowness is due to the size of the table so server side pagination will help.

We used LaunchDarkly to enable a new table that is paginated. We hope to improve the user experience and reduce load on the database.

User Accounts

The application is secured using a very basic framework. These are the users that are configured for each scenario. When using the application, use the logins below when evaluating different scenarios.

Login Name	Password	Groups	Senario
jojo	gold	USER	Part 1
samone	gold	USER,QA_TESTER	Part 2
skeet	gold	USER	Part 2
surfer	gold	USER,QA_TESTER	Part 2
slater	gold	USER	Experiment
lee	gold	USER	Experiment

Using the App

The application should be started from a command line prompt. The following will detail how to get setup and start the app.

Configuration

These are the configuration steps required to get the application working.

I'm assuming you have access to a modern shell. I used zsh which is the default on a mac. Make sure java and gradle are installed. I'm also assuming you know the basics of gradle.

brew update && brew upgrade
brew install java@21
brew install gradle
brew install jq
brew tap launchdarkly/homebrew-tap
brew install ldcli

Clone the repo and change directories to it. I'll assume you know what you are doing, so I'll ignore directory names, etc.

git clone https://github.com/jonnio/launchdarkly-homework.git
cd launchdarkly-homework

The application needs at least Java 21 so make sure you either have it setup by running

./gradlew --version

and verifying that the output is similar to this with at least Java 21.

------------------------------------------------------------
Gradle 8.8
------------------------------------------------------------

Build time:   2024-05-31 21:46:56 UTC
Revision:     4bd1b3d3fc3f31db5a26eecb416a165b8cc36082

Kotlin:       1.9.22
Groovy:       3.0.21
Ant:          Apache Ant(TM) version 1.10.13 compiled on January 4 2023
JVM:          21.0.4 (Homebrew 21.0.4)
OS:           Mac OS X 14.5 x86_64

If you have the incorrect version of java, you've installed the correct version using brew, and have created the symlink (per brew instructions), export JAVA_HOME=`/usr/libexec/java_home -v 21` will usually get you to the right place. Gradle will respect your JAVA_HOME environment variable.

Run the application

Build and start the application from the command line. It is a Spring Boot app so we can easily start it using the gradle plugin that is already configured.

./gradlew clean bootRun

Login and Logout

Navigate to http://localhost:8080/ to login.

Click the Logout link in the upper right of the menu to logout of the application and change users.

Environment Notes

• I used only the proudction environment per the instructions
• I did the configuration manually on the webpage but did experiment with doing it from a shell script
• Testing automation should be enabled
• I did not have time to set up a cypress test suite for testing automation

Technical Exercises

The technical exercises will require logging in as different users. It will also require the use of the ldcli to turn a flag on and off. Configure the ldcli using the command line:

ldcli config --set access-token api-c66f6280-cda1-4149-9c44-6db333b9ac15

The token presented here will be removed after the evaluation period.

The feature flag used here can be queried with the CLI (pipe to jq for formatting in iTerm2):

ldcli flags get --project default --env production --flag feature-olympic-pagination | jq

Part 1: Release and Remediate

• Make sure the flag feature-olympic-pagination is disabled
• Login to the application using the user samone. The user will be presented with a table of medals that has scrolling but no pagination. A user can simply sort by a column and scroll.
• Enable the pagination feature and note that the screen updates with a pageable table interface.

ldcli flags --project default --environment production --flag feature-olympic-pagination toggle-on |jq -r '{name, kind, key, on: .environments.production.on}'

• Disable pagination by turning the flag off

ldcli flags --project default --environment production --flag feature-olympic-pagination toggle-off |jq -r '{name, kind, key, on: .environments.production.on}'

• Checkout the code for the client listener on line 185 in index.html
• Checkout the code for the server listener on line 30 in LaunchDarklyConfiguration.java. The server listener simply logs the event.

Part 2: Target

Utilize the individual and rule based targeting by logging in as individual people. Make sure the flag is enabled:

ldcli flags --project default --environment production --flag feature-olympic-pagination toggle-on |jq -r '{name, kind, key, on: .environments.production.on}'

Individual Targeting

The user jojo will not have pagination. A target is configured so the user skeet does have pagination.

• Login as jojo and see that the pagination is not available
• Login as skeet and see that pagination is enabled

Rule Targeting

A rule is configured such that any user with the role QA_TESTER will have pagination enabled.

• Login as surfer or samone to see the pagination (logout)
• Login as jojo to see that pagination is not enabled (logout)

Extra Credit: Experimentation

I've added an experiment that tracks the clicks on the pagination buttons. The experiment uses a css filter to track clicks on the buttons. Some sample results are in this screen shot:

Extra Credit: Integrations

I created an integration between LaunchDarkly and my GCP account via pub/sub to store the events for future analytics and reporting. (screenshot pending enablement of integrations)