[GoLang] Adding FeatureFlags using github repo

What is feature flag?

There is a post by Martin Fowler on feature flag, and can be found here.

By 200degrees

In our last post: Self-Updating binaries for Go, we utilized the github platform to add a functionality in our go application for self update, and today, we will add one more tool in our arsenal of using powerful feature-flags by storing a file in github-repo.

Problem statement: Now, we have developed an application with rich of features, however, we want to test new features for a specific set of users before rolling out for everyone.

Premium services: There are paid services that provide this feature out of the box, like the configcat, launchdarkly, etc.

Opensource solution: gofeatureflag, sourcecode: github

go-feature-flag

How to use the go-feature-flag?

1. Let’s start with an empty project. Source code for the project

GitHub - sarvsav/golang-tag-example at go_feature_flag_example

2. Initialize the go-feature-flag module using the below command:

go get github.com/thomaspoignant/go-feature-flag

3. Now, we need a github repo to host the flag file, which sets the feature values to enable or disable for the set of users. Below is an example of the sample flag YAML file

new-admin-access:
  variations:
    default_var: false
    false_var: false
    true_var: true
  defaultRule:
    percentage:
      false_var: 20
      true_var: 80

flag-only-for-admin:
  variations:
    default_var: false
    false_var: false
    true_var: true
  targeting:
    - query: admin eq true
      percentage:
        false_var: 0
        true_var: 100
  defaultRule:
    variation: Default

The code for whole repository can be download from here: