feature-flag-demo

Feature flags do not just support DevOps/operations' use cases, but can support development, product management and other roles within an organization. This project exists to exercise these use cases across multiple roles within an organization.

This is a project to demonstrate some common and not so common feature flag use cases. A single web page shows 20 concurrently connected web users and how feature flag can alter each user's experience.

Disclaimer: This projects is to explain the concept of feature flags and their use cases. By no means, is this project designed to show how to implement feature flags, especially Unleash. Unleash was used, since it was an open source feature flag system. However, to complete some of our feature flag use cases, we exploit the userID and variations with Unleash. In a production system, we would have implemented our own Unleash strategies.

Required Software to Run

• Docker 19.03.5 or higher
• Node 10.15.1 or higher

Commands to Run

Run all the commands below from the project root folder.

1. npm run start:feature-flags, this starts the DB and Unleash. This will remain running, so you will need another terminal for the other commands.
2. npm run load-flags, this loads the required data into the DB. This command is idempotent, so it can be run over an over with no issues.
3. npm run start:web, starts the web app simulating 20 different users concurrently using an app.

Now you can access Unleash and the web app.

• Unleash will be available at http://localhost:4242
• Web app is available at http://localhost:3000

Toggling the Flags

When toggling the flags, give it up to 20 seconds for an effect. It takes awhile for the change to happen.

Demo Sequence

1. All users have the same active web experience
2. All users experience site maintenance
3. Admins and test users can access the site, while others remain in maintenance mode
4. All users have the same active web experience
5. Show a better experience, by announcing upcoming maintenance before going into maintenance mode
6. Admins and test users can access the site, while others remain in maintenance mode
7. All users have the same active web experience
8. Kill a specific user
9. All users have the same active web experience
10. Incremental rollout v2
11. All users have the same v2 active web experience
12. Some users get A and others get B UI designs
13. All users have the same v2 with A applied active web experience
14. Calendar release v3 to all users
15. All users have the same v3 with A applied active web experience
16. Some users get freemium and other get paid access
17. Turn on debug logging for one user having troubles

Possible Use Cases

Feature flags have mature and have merged with other capabilities like remote configuration and user analytics. Combined together, feature flags today can support several different use cases across several functional roles. These functional roles include, project management, DevOps/Operations, development, technical support and much more. Here is a further breakdown of these roles into the use cases.

DevOps/Operations

• Maintenance mode (X)
  • Does not allow the user to user the app while in this mode
• Banner notification (X)
  • User gets a notify of crucial info in a very obvious and visible manner, so they do not miss it
• Kill switch
  • Target specific users and remove their ability to use the application
• Incremental roll outs/canary launch
  • Slowly roll out a release to a small number to ensure smooth running before expanding to the whole user base

Product Management

• Block/allow users
  • Block and allow users based on any relevant factor like, location, type of credit card used or anything the business deems correct
• Early access/beta access
  • Allow access to people who are early access/beta users
• A/B testing
  • Randomly provide different experiences from UI design to user flows in the app, so you can find what works best for your app
• Calendar driven launches
  • With feature flags, deployment does not equal release. This allows the product team to deploy at a specific date an time for that new relase!

Development

• Subscriptions
  • Instead of building out a subscription system in your app, use feature flags
• Newbie vs. power user
  • Restrict power in the app to people who have been trained to use it
• Single trunk branching
  • Features flags work great with single trunk branching, which allows for short lived branches and incomplete work to go to production
• Test in production
  • "Does it work in production?" is a bad question to ask, so go test it before you release it using feature flags

Support

• User targeted debug/verbose logging
  • Wouldn't it be great to get detailed logs about a user's problem without having to turn debug logging on for everyone? Well, now your support staff can do it to help troubleshoot user issues sooner.