📣 Notify flag changes
Overview
In GO Feature Flag, if you want to be informed when a flag has changed, you can configure a notifier.
A notifier will send one notification to the targeted system to inform them that a new flag configuration has been loaded.
About notifiers
Notifiers are useful for a variety of purposes, such as:
- Information: Notifiers can send to your team chat a notification that a feature flag has changed.
- Reacting to flag changes: Using the webhook notifier, you can trigger any action you want in your system to react to flag changes.
When the GO Feature Flag client detects a change in the configuration through the retriever's polling mechanism, it triggers the configured notifiers.
GO Feature Flag can handle more than one notifier at a time.
By nature, GO Feature Flag is 100% stateless, so if you run multiple instance of GO Feature Flag, you will receive notification for changes from each instance.
In each notification you will have the hostname of the instance, it can be useful if you have multiple GO Feature Flag running.
You have 2 different ways to specify a notifier depending on if you are using the GO Module or the Relay Proxy. In all the details pages of the retrievers bellow you will have an example for both examples.
Available Notifiers
Bellow is the full list of notifiers that are available in GO Feature Flag.
Custom notifier
If you have a specific use case that is not covered by the built-in notifiers, you can create your own custom exporter.
To create a custom notifier you must have a struct that implements the notifier.Notifier interface.
In param you will receive a notifier.DiffCache struct that will tell you what has changed in your flag configuration.
import (
ffclient "github.com/thomaspoignant/go-feature-flag"
"github.com/thomaspoignant/go-feature-flag/notifier/notifier"
"sync"
)
type Notifier struct{}
func (c *Notifier) Notify(diff notifier.DiffCache) error {
// ...
// do whatever you want here
}
If you think your custom notifier could be useful for others, feel free to open a pull request to add it to the list of available notifiers.
If you are using a custom exporter, it is easy to use it for the GO Module, but if you want to use it in the relay proxy you will have to recompile it yourself.