on-update functionality in example

Makefile

@@ -13,8 +13,18 @@ dependencies_up: dependencies_down
 tests:
 	go test -v ./...
 
-.PHONY: example
+.PHONY: build-example
 ## example: runs an http-server locally
-example:
+build-example:
 	go build -o bin/server github.com/rbroggi/streamingconfig/example/server
-	./bin/server
+	go build -o bin/app github.com/rbroggi/streamingconfig/example/app
+
+.PHONY: run-example-server
+## run-example-server: runs an http-server locally
+run-example-server: build-example
+	./bin/server
+
+.PHONY: run-example-app
+## run-example-app: runs an http-server locally
+run-example-app: build-example
+	./bin/app

README.md

@@ -109,17 +109,17 @@ make dependencies_up
 make tests
 ```
 
-### Run example server
+### Run example 
 
+Start by starting the dependencies (mongo), and run the example-server which is a simple HTTP server to receive GET,POST requests for reading/updating configurations.
 ```shell
 make dependencies_up
-make example
+make run-example-server
 ```
-
-Optionally, you can also start a second server to check that the changes happening in one server will be reflected in the other:
+on a different shell, run the sample APP, which is an app that receives changes upon changes that happen in the configuration through the server API endpoints.
 
 ```shell
-HTTP_PORT=8081 make example
+make run-example-app
 ```
 
 #### Getting latest configuration request

example/app/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"log/slog"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	config "github.com/rbroggi/streamingconfig"
+	appcfg "github.com/rbroggi/streamingconfig/example/config"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+func main() {
+	runnableCtx, cancelRunnables := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer cancelRunnables()
+	_, done := initRepo(runnableCtx)
+	// until shutdown signal is sent
+	<-runnableCtx.Done()
+	<-done
+}
+
+func initRepo(ctx context.Context) (*config.WatchedRepo[*appcfg.Conf], <-chan struct{}) {
+	lgr := slog.Default()
+	db := getDb()
+	repo, err := config.NewWatchedRepo[*appcfg.Conf](
+		config.Args{
+			Logger: lgr,
+			DB:     db,
+		}, config.WithOnUpdate[*appcfg.Conf](func(conf *appcfg.Conf) {
+			lgr.With("cfg", conf).Debug("config updated")
+			slog.SetLogLoggerLevel(conf.LogLevel)
+		}))
+	if err != nil {
+		log.Fatal(err)
+	}
+	done, err := repo.Start(ctx)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return repo, done
+}
+
+func getDb() *mongo.Database {
+	ctx, cnl := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cnl()
+	// use test name as db name to parallel tests.
+	opts := options.Client()
+	opts.ApplyURI("mongodb://localhost:27017/?connect=direct")
+	client, err := mongo.Connect(ctx, opts)
+	if err != nil {
+		panic(fmt.Errorf("run `make dependencies_up` before, error: %w", err))
+	}
+	err = client.Ping(ctx, nil)
+	if err != nil {
+		panic(fmt.Errorf("error %v\nrun `make dependencies_up` before running main\n", err))
+	}
+	return client.Database("test")
+}

example/config/config.go

@@ -0,0 +1,27 @@
+package config
+
+import (
+	"errors"
+	"log/slog"
+
+	config "github.com/rbroggi/streamingconfig"
+)
+
+type Conf struct {
+	LogLevel slog.Level `json:"logLevel" default:"\"DEBUG\""`
+	Name     string     `json:"name" default:"john"`
+	Age      int        `json:"age"`
+	Friends  []string   `json:"friends" default:"[\"mark\",\"tom\",\"jack\"]"`
+}
+
+func (c *Conf) Update(new config.Config) error {
+	newCfg, ok := new.(*Conf)
+	if !ok {
+		return errors.New("wrong configuration")
+	}
+	c.Name = newCfg.Name
+	c.Age = newCfg.Age
+	c.Friends = newCfg.Friends
+	c.LogLevel = newCfg.LogLevel
+	return nil
+}

example/server/configs.http

@@ -7,9 +7,10 @@ PUT http://localhost:8080/configs/latest
 user-id: pippo
 
 {
-  "name": "gloria",
-  "age": 38,
-  "friends": ["joe", "mark"]
+  "name": "john",
+  "logLevel": "DEBUG",
+  "age": 40,
+  "friends": ["jack", "doug"]
 }
 
 ### List config versions

example/server/main.go

@@ -13,28 +13,12 @@ import (
 	"time"
 
 	config "github.com/rbroggi/streamingconfig"
+	appcfg "github.com/rbroggi/streamingconfig/example/config"
 
 	"go.mongodb.org/mongo-driver/mongo"
 	"go.mongodb.org/mongo-driver/mongo/options"
 )
 
-type conf struct {
-	Name    string   `json:"name" default:"john"`
-	Age     int      `json:"age"`
-	Friends []string `json:"friends" default:"[\"mark\",\"tom\",\"jack\"]"`
-}
-
-func (c *conf) Update(new config.Config) error {
-	newCfg, ok := new.(*conf)
-	if !ok {
-		return errors.New("wrong configuration")
-	}
-	c.Name = newCfg.Name
-	c.Age = newCfg.Age
-	c.Friends = newCfg.Friends
-	return nil
-}
-
 func main() {
 	port := os.Getenv("HTTP_PORT")
 	if port == "" {
@@ -75,10 +59,10 @@ func main() {
 	<-done
 }
 
-func initRepo(ctx context.Context) (*config.WatchedRepo[*conf], <-chan struct{}) {
+func initRepo(ctx context.Context) (*config.WatchedRepo[*appcfg.Conf], <-chan struct{}) {
 	lgr := slog.Default()
 	db := getDb()
-	repo, err := config.NewWatchedRepo[*conf](
+	repo, err := config.NewWatchedRepo[*appcfg.Conf](
 		config.Args{
 			Logger: lgr,
 			DB:     db,

example/server/server.go

@@ -9,11 +9,12 @@ import (
 	"strconv"
 
 	config "github.com/rbroggi/streamingconfig"
+	appcfg "github.com/rbroggi/streamingconfig/example/config"
 )
 
 type server struct {
 	lgr  *slog.Logger
-	repo *config.WatchedRepo[*conf]
+	repo *config.WatchedRepo[*appcfg.Conf]
 }
 
 // latestConfigHandler returns the latest configuration
@@ -50,7 +51,7 @@ func (s *server) putConfigHandler(w http.ResponseWriter, r *http.Request) {
 	// Close the body to avoid leaks
 	defer r.Body.Close()
 
-	cfg := new(conf)
+	cfg := new(appcfg.Conf)
 	err = json.Unmarshal(body, cfg)
 	if err != nil {
 		s.lgr.With("error", err).ErrorContext(r.Context(), "unmarshalling request into configuration")
@@ -59,7 +60,7 @@ func (s *server) putConfigHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	updated, err := s.repo.UpdateConfig(r.Context(), config.UpdateConfigCmd[*conf]{
+	updated, err := s.repo.UpdateConfig(r.Context(), config.UpdateConfigCmd[*appcfg.Conf]{
 		By:     userID,
 		Config: cfg,
 	})