examples/retriever_configmap/main.go

package main

import (
	"context"
	"fmt"
	"github.com/thomaspoignant/go-feature-flag/ffcontext"
	"log"
	"log/slog"
	"net/http"
	"time"

	"github.com/thomaspoignant/go-feature-flag/retriever/k8sretriever"
	"k8s.io/client-go/rest"

	ffclient "github.com/thomaspoignant/go-feature-flag"
)

func main() {
	// Init ffclient with a kubernetes configmap retriever.
	config, err := rest.InClusterConfig()
	if err != nil {
		panic(err.Error())
	}

	err = ffclient.Init(ffclient.Config{
		PollingInterval: 10 * time.Second,
		LeveledLogger:   slog.Default(),
		Context:         context.Background(),
		Retriever: &k8sretriever.Retriever{
			Namespace:     "default",
			ConfigMapName: "goff",
			Key:           "flags.goff.yaml",
			ClientConfig:  *config,
		},
	})

	// Check init errors.
	if err != nil {
		log.Fatal(err)
	}
	// defer closing ffclient
	defer ffclient.Close()

	http.HandleFunc("/", handler)
	http.ListenAndServe(":8080", nil)
}

func handler(w http.ResponseWriter, req *http.Request) {
	user1 := ffcontext.
		NewEvaluationContextBuilder("aea2fdc1-b9a0-417a-b707-0c9083de68e3").
		AddCustom("anonymous", true).
		Build()
	user2 := ffcontext.NewEvaluationContext("332460b9-a8aa-4f7a-bc5d-9cc33632df9a")
	user3 := ffcontext.NewEvaluationContextBuilder("785a14bf-d2c5-4caa-9c70-2bbc4e3732a5").
		AddCustom("email", "user2@email.com").
		AddCustom("firstname", "John").
		AddCustom("lastname", "Doe").
		AddCustom("admin", true).
		Build()

	// --- test flag with no rule
	// user1
	user1HasAccessToNewAdmin, err := ffclient.BoolVariation("new-admin-access", user1, false)
	if err != nil {
		// we log the error, but we still have a meaningful value in user1HasAccessToNewAdmin (the default value).
		log.Printf("something went wrong when getting the flag: %v", err)
	}
	if user1HasAccessToNewAdmin {
		fmt.Fprintf(w, "user1 has access to the new admin\n")
	}

	// user2
	user2HasAccessToNewAdmin, err := ffclient.BoolVariation("new-admin-access", user2, false)
	if err != nil {
		// we log the error, but we still have a meaningful value in hasAccessToNewAdmin (the default value).
		fmt.Fprintf(w, "something went wrong when getting the flag: %v\n", err)
	}
	if !user2HasAccessToNewAdmin {
		fmt.Fprintf(w, "user2 has not access to the new admin\n")
	}

	// --- test flag with rule only for admins
	// user 1 is not admin so should not access to the flag
	user1HasAccess, _ := ffclient.BoolVariation("flag-only-for-admin", user1, false)
	if !user1HasAccess {
		fmt.Fprintf(w, "user1 is not admin so no access to the flag\n")
	}

	// user 3 is admin and the flag apply to this key.
	if user3HasAccess, _ := ffclient.BoolVariation("flag-only-for-admin", user3, false); user3HasAccess {
		fmt.Fprintf(w, "user 3 is admin and the flag apply to this key.\n")
	}
}