feat(example): Allow configuring some parameters with env variables (#663)

Co-authored-by: Andrey Rusakov <andrey.rusakov@camptocamp.com>

example/server/config/config.go

@@ -0,0 +1,40 @@
+package config
+
+import (
+	"os"
+	"strings"
+)
+
+const (
+	// default port for the http server to run
+	DefaultIssuerPort = "9998"
+)
+
+type Config struct {
+	Port        string
+	RedirectURI []string
+	UsersFile   string
+}
+
+// FromEnvVars loads configuration parameters from environment variables.
+// If there is no such variable defined, then use default values.
+func FromEnvVars(defaults *Config) *Config {
+	if defaults == nil {
+		defaults = &Config{}
+	}
+	cfg := &Config{
+		Port:        defaults.Port,
+		RedirectURI: defaults.RedirectURI,
+		UsersFile:   defaults.UsersFile,
+	}
+	if value, ok := os.LookupEnv("PORT"); ok {
+		cfg.Port = value
+	}
+	if value, ok := os.LookupEnv("USERS_FILE"); ok {
+		cfg.UsersFile = value
+	}
+	if value, ok := os.LookupEnv("REDIRECT_URI"); ok {
+		cfg.RedirectURI = strings.Split(value, ",")
+	}
+	return cfg
+}

example/server/config/config_test.go

@@ -0,0 +1,77 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+func TestFromEnvVars(t *testing.T) {
+
+	for _, tc := range []struct {
+		name     string
+		env      map[string]string
+		defaults *Config
+		want     *Config
+	}{
+		{
+			name: "no vars, no default values",
+			env:  map[string]string{},
+			want: &Config{},
+		},
+		{
+			name: "no vars, only defaults",
+			env:  map[string]string{},
+			defaults: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+			want: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+		},
+		{
+			name: "overriding default values",
+			env: map[string]string{
+				"PORT":         "1234",
+				"USERS_FILE":   "/path/to/users",
+				"REDIRECT_URI": "http://redirect/redirect",
+			},
+			defaults: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+			want: &Config{
+				Port:        "1234",
+				UsersFile:   "/path/to/users",
+				RedirectURI: []string{"http://redirect/redirect"},
+			},
+		},
+		{
+			name: "multiple redirect uris",
+			env: map[string]string{
+				"REDIRECT_URI": "http://host_1,http://host_2,http://host_3",
+			},
+			want: &Config{
+				RedirectURI: []string{
+					"http://host_1", "http://host_2", "http://host_3",
+				},
+			},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			os.Clearenv()
+			for k, v := range tc.env {
+				os.Setenv(k, v)
+			}
+			cfg := FromEnvVars(tc.defaults)
+			if fmt.Sprint(cfg) != fmt.Sprint(tc.want) {
+				t.Errorf("Expected FromEnvVars()=%q, but got %q", tc.want, cfg)
+			}
+		})
+	}
+}

example/server/main.go

@@ -5,20 +5,33 @@ import (
 	"log/slog"
 	"net/http"
 	"os"
-	"strings"
 
+	"github.com/zitadel/oidc/v3/example/server/config"
 	"github.com/zitadel/oidc/v3/example/server/exampleop"
 	"github.com/zitadel/oidc/v3/example/server/storage"
 )
 
+func getUserStore(cfg *config.Config) (storage.UserStore, error) {
+	if cfg.UsersFile == "" {
+		return storage.NewUserStore(fmt.Sprintf("http://localhost:%s/", cfg.Port)), nil
+	}
+	return storage.StoreFromFile(cfg.UsersFile)
+}
+
 func main() {
-	//we will run on :9998
-	port := "9998"
+	cfg := config.FromEnvVars(&config.Config{Port: "9998"})
+	logger := slog.New(
+		slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
+			AddSource: true,
+			Level:     slog.LevelDebug,
+		}),
+	)
+
 	//which gives us the issuer: http://localhost:9998/
-	issuer := fmt.Sprintf("http://localhost:%s/", port)
+	issuer := fmt.Sprintf("http://localhost:%s/", cfg.Port)
 
 	storage.RegisterClients(
-		storage.NativeClient("native", strings.Split(os.Getenv("REDIRECT_URI"), ",")...),
+		storage.NativeClient("native", cfg.RedirectURI...),
 		storage.WebClient("web", "secret"),
 		storage.WebClient("api", "secret"),
 	)
@@ -26,23 +39,20 @@ func main() {
 	// the OpenIDProvider interface needs a Storage interface handling various checks and state manipulations
 	// this might be the layer for accessing your database
 	// in this example it will be handled in-memory
-	storage := storage.NewStorage(storage.NewUserStore(issuer))
-
-	logger := slog.New(
-		slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
-			AddSource: true,
-			Level:     slog.LevelDebug,
-		}),
-	)
+	store, err := getUserStore(cfg)
+	if err != nil {
+		logger.Error("cannot create UserStore", "error", err)
+		os.Exit(1)
+	}
+	storage := storage.NewStorage(store)
 	router := exampleop.SetupServer(issuer, storage, logger, false)
 
 	server := &http.Server{
-		Addr:    ":" + port,
+		Addr:    ":" + cfg.Port,
 		Handler: router,
 	}
-	logger.Info("server listening, press ctrl+c to stop", "addr", fmt.Sprintf("http://localhost:%s/", port))
-	err := server.ListenAndServe()
-	if err != http.ErrServerClosed {
+	logger.Info("server listening, press ctrl+c to stop", "addr", issuer)
+	if server.ListenAndServe() != http.ErrServerClosed {
 		logger.Error("server terminated", "error", err)
 		os.Exit(1)
 	}

example/server/storage/user.go

@@ -2,6 +2,8 @@ package storage
 
 import (
 	"crypto/rsa"
+	"encoding/json"
+	"os"
 	"strings"
 
 	"golang.org/x/text/language"
@@ -35,6 +37,18 @@ type userStore struct {
 	users map[string]*User
 }
 
+func StoreFromFile(path string) (UserStore, error) {
+	users := map[string]*User{}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(data, &users); err != nil {
+		return nil, err
+	}
+	return userStore{users}, nil
+}
+
 func NewUserStore(issuer string) UserStore {
 	hostname := strings.Split(strings.Split(issuer, "://")[1], ":")[0]
 	return userStore{

example/server/storage/user_test.go

@@ -0,0 +1,70 @@
+package storage
+
+import (
+	"os"
+	"path"
+	"reflect"
+	"testing"
+
+	"golang.org/x/text/language"
+)
+
+func TestStoreFromFile(t *testing.T) {
+	for _, tc := range []struct {
+		name       string
+		pathToFile string
+		content    string
+		want       UserStore
+		wantErr    bool
+	}{
+		{
+			name:       "normal user file",
+			pathToFile: "userfile.json",
+			content: `{
+				"id1": {
+					"ID":                "id1",
+					"EmailVerified":     true,
+					"PreferredLanguage": "DE"
+				}
+			}`,
+			want: userStore{map[string]*User{
+				"id1": {
+					ID:                "id1",
+					EmailVerified:     true,
+					PreferredLanguage: language.German,
+				},
+			}},
+		},
+		{
+			name:       "malformed file",
+			pathToFile: "whatever",
+			content:    "not a json just a text",
+			wantErr:    true,
+		},
+		{
+			name:       "not existing file",
+			pathToFile: "what/ever/file",
+			wantErr:    true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			actualPath := path.Join(t.TempDir(), tc.pathToFile)
+
+			if tc.content != "" && tc.pathToFile != "" {
+				if err := os.WriteFile(actualPath, []byte(tc.content), 0666); err != nil {
+					t.Fatalf("cannot create file with test content: %q", tc.content)
+				}
+			}
+			result, err := StoreFromFile(actualPath)
+			if err != nil && !tc.wantErr {
+				t.Errorf("StoreFromFile(%q) returned unexpected error %q", tc.pathToFile, err)
+			} else if err == nil && tc.wantErr {
+				t.Errorf("StoreFromFile(%q) did not return an expected error", tc.pathToFile)
+			}
+			if !tc.wantErr && !reflect.DeepEqual(tc.want, result.(userStore)) {
+				t.Errorf("expected StoreFromFile(%q) = %v, but got %v",
+					tc.pathToFile, tc.want, result)
+			}
+		})
+	}
+}