Replace config object with option pattern (#23)

* Replace config objects with option pattern

correlation_id/config.go

@@ -11,11 +11,37 @@ type Config struct {
 	IdGenerator func(*http.Request) string
 }
 
-func NewConfig() *Config {
-	return &Config{
+func (c *Config) apply(options ...Option) *Config {
+	for _, option := range options {
+		option(c)
+	}
+	return c
+}
+
+// GetConfig returns a new correlation configuration with all options applied
+func GetConfig(options ...Option) *Config {
+	config := &Config{
 		HeaderName: HeaderName,
 		IdGenerator: func(_ *http.Request) string {
 			return DefaultIdGenerator.Generate(10)
 		},
 	}
+	return config.apply(options...)
+}
+
+// Option defines a correlationId middleware/tripperware configuration option
+type Option func(*Config)
+
+// WithHeaderName will configure HeaderName correlation option
+func WithHeaderName(headerName string) Option {
+	return func(config *Config) {
+		config.HeaderName = headerName
+	}
+}
+
+// WithIdGenerator will configure IdGenerator correlation option
+func WithIdGenerator(idGenerator func(*http.Request) string) Option {
+	return func(config *Config) {
+		config.IdGenerator = idGenerator
+	}
 }

correlation_id/config_test.go

@@ -2,6 +2,7 @@ package correlation_id_test
 
 import (
 	"math/rand"
+	"net/http"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -14,6 +15,17 @@ func TestNewConfig(t *testing.T) {
 	correlation_id.DefaultIdGenerator = correlation_id.NewRandomIdGenerator(defaultRand)
 
 	for _, expectedId := range []string{"p1LGIehp1s", "uqtCDMLxiD"} {
-		assert.Equal(t, expectedId, correlation_id.NewConfig().IdGenerator(nil))
+		assert.Equal(t, expectedId, correlation_id.GetConfig().IdGenerator(nil))
 	}
 }
+
+func TestConfig_Options(t *testing.T) {
+	config := correlation_id.GetConfig(
+		correlation_id.WithHeaderName("my-personal-header-name"),
+		correlation_id.WithIdGenerator(func(request *http.Request) string {
+			return "toto"
+		}),
+	)
+	assert.Equal(t, "my-personal-header-name", config.HeaderName)
+	assert.Equal(t, "toto", config.IdGenerator(nil))
+}

metrics/config.go

@@ -3,22 +3,30 @@ package metrics
 import "net/http"
 
 type Config struct {
-	Recorder                Recorder
+	Recorder Recorder
 	// func that allows you to provide a strategy to identify/group metrics
 	// you can group metrics by request host/url/... or app name ...
 	// by default, we group metrics by request url
-	IdentifierProvider      func(req *http.Request) string
+	IdentifierProvider func(req *http.Request) string
 	// if set to true, each response status will be represented by a metrics
 	// if set to false, response status codes will be grouped by first digit (204/201/200/... -> 2xx; 404/403/... -> 4xx)
-	SplitStatus             bool
+	SplitStatus bool
 	// if set to true, recorder will add a responseSize metric
-	ObserveResponseSize     bool
+	ObserveResponseSize bool
 	// if set to true, recorder will add a metric representing the number of inflight requests
 	MeasureInflightRequests bool
 }
 
-func NewConfig(recorder Recorder) *Config {
-	return &Config{
+func (c *Config) apply(options ...Option) *Config {
+	for _, option := range options {
+		option(c)
+	}
+	return c
+}
+
+// NewConfig returns a new metrics configuration with all options applied
+func NewConfig(recorder Recorder, options ...Option) *Config {
+	config := &Config{
 		Recorder:                recorder,
 		SplitStatus:             false,
 		ObserveResponseSize:     true,
@@ -27,4 +35,36 @@ func NewConfig(recorder Recorder) *Config {
 			return req.URL.String()
 		},
 	}
+	return config.apply(options...)
+}
+
+// Option defines a metrics middleware/tripperware configuration option
+type Option func(*Config)
+
+// WithSplitStatus will configure SplitStatus metrics option
+func WithSplitStatus(splitStatus bool) Option {
+	return func(config *Config) {
+		config.SplitStatus = splitStatus
+	}
+}
+
+// WithObserveResponseSize will configure ObserveResponseSize metrics option
+func WithObserveResponseSize(observeResponseSize bool) Option {
+	return func(config *Config) {
+		config.ObserveResponseSize = observeResponseSize
+	}
+}
+
+// WithMeasureInflightRequests will configure MeasureInflightRequests metrics option
+func WithMeasureInflightRequests(measureInflightRequests bool) Option {
+	return func(config *Config) {
+		config.MeasureInflightRequests = measureInflightRequests
+	}
+}
+
+// WithIdentifierProvider will configure IdentifierProvider metrics option
+func WithIdentifierProvider(identifierProvider func(req *http.Request) string) Option {
+	return func(config *Config) {
+		config.IdentifierProvider = identifierProvider
+	}
 }

metrics/config_test.go

@@ -0,0 +1,27 @@
+package metrics_test
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/gol4ng/httpware/metrics"
+)
+
+func TestConfig_Options(t *testing.T) {
+	var recorder metrics.Recorder
+	config := metrics.NewConfig(
+		recorder,
+		metrics.WithSplitStatus(true),
+		metrics.WithObserveResponseSize(false),
+		metrics.WithMeasureInflightRequests(false),
+		metrics.WithIdentifierProvider(func(req *http.Request) string {
+			return "my-personal-identifier"
+		}),
+	)
+	assert.Equal(t, true, config.SplitStatus)
+	assert.Equal(t, false, config.ObserveResponseSize)
+	assert.Equal(t, false, config.MeasureInflightRequests)
+	assert.Equal(t, "my-personal-identifier", config.IdentifierProvider(nil))
+}

middleware/correlation_id.go

@@ -10,7 +10,8 @@ import (
 
 // CorrelationId middleware get request id header if provided or generate a request id
 // It will add the request ID to request context and add it to response header to
-func CorrelationId(config *correlation_id.Config) httpware.Middleware {
+func CorrelationId(options ...correlation_id.Option) httpware.Middleware {
+	config := correlation_id.GetConfig(options...)
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(writer http.ResponseWriter, req *http.Request) {
 			id := req.Header.Get(config.HeaderName)

middleware/correlation_id_test.go

@@ -30,7 +30,7 @@ func TestCorrelationId(t *testing.T) {
 		handlerReq = r
 	})
 
-	middleware.CorrelationId(correlation_id.NewConfig())(handler).ServeHTTP(responseWriter, req)
+	middleware.CorrelationId()(handler).ServeHTTP(responseWriter, req)
 	respHeaderValue := responseWriter.Header().Get(correlation_id.HeaderName)
 	reqContextValue := handlerReq.Context().Value(correlation_id.HeaderName).(string)
 	assert.Equal(t, "p1LGIehp1s", req.Header.Get(correlation_id.HeaderName))
@@ -45,19 +45,15 @@ func TestCorrelationId(t *testing.T) {
 
 func ExampleCorrelationId() {
 	port := ":5001"
-
-	config := correlation_id.NewConfig()
-	// you can override default header name
-	config.HeaderName = "my-personal-header-name"
-	// you can override default id generator
-	config.IdGenerator = func(request *http.Request) string {
-		return "my-fixed-request-id"
-	}
-
 	// we recommend to use MiddlewareStack to simplify managing all wanted middlewares
 	// caution middleware order matters
 	stack := httpware.MiddlewareStack(
-		middleware.CorrelationId(config),
+		middleware.CorrelationId(
+			correlation_id.WithHeaderName("my-personal-header-name"),
+			correlation_id.WithIdGenerator(func(request *http.Request) string {
+				return "my-fixed-request-id"
+			}),
+		),
 	)
 
 	srv := http.NewServeMux()
@@ -68,7 +64,7 @@ func ExampleCorrelationId() {
 	}()
 
 	resp, err := http.Get("http://localhost" + port)
-	fmt.Printf("%s: %v %v\n", config.HeaderName, resp.Header.Get(config.HeaderName), err)
+	fmt.Printf("%s: %v %v\n", "my-personal-header-name", resp.Header.Get("my-personal-header-name"), err)
 
 	//Output: my-personal-header-name: my-fixed-request-id <nil>
 }

middleware/metrics.go

@@ -10,7 +10,8 @@ import (
 	"github.com/gol4ng/httpware/metrics"
 )
 
-func Metrics(config *metrics.Config) httpware.Middleware {
+func Metrics(recorder metrics.Recorder, options ... metrics.Option) httpware.Middleware {
+	config := metrics.NewConfig(recorder, options...)
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(writer http.ResponseWriter, req *http.Request) {
 			writerInterceptor := NewResponseWriterInterceptor(writer)

middleware/metrics_test.go

@@ -36,7 +36,7 @@ func TestMetrics(t *testing.T) {
 	}
 	// create metrics httpClient middleware
 	stack := httpware.MiddlewareStack(
-		middleware.Metrics(metrics.NewConfig(recorderMock)),
+		middleware.Metrics(recorderMock),
 	)
 
 	// assert recorder calls
@@ -65,16 +65,12 @@ func ExampleMetrics() {
 
 	recorder := prom.NewRecorder(prom.Config{}).RegisterOn(nil)
 
-	metricsConfig := metrics.NewConfig(recorder)
-	// you can override default identifier provider
-	metricsConfig.IdentifierProvider = func(req *http.Request) string {
-		return req.URL.Host + " -> " + req.URL.Path
-	}
-
 	// we recommend to use MiddlewareStack to simplify managing all wanted middleware
 	// caution middleware order matter
 	stack := httpware.MiddlewareStack(
-		middleware.Metrics(metricsConfig),
+		middleware.Metrics(recorder, metrics.WithIdentifierProvider(func(req *http.Request) string {
+			return req.URL.Host + " -> " + req.URL.Path
+		})),
 	)
 
 	srv := http.NewServeMux()

middleware_test.go

@@ -2,6 +2,7 @@ package httpware_test
 
 import (
 	"fmt"
+	"github.com/gol4ng/httpware/correlation_id"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -207,6 +208,11 @@ func ExampleMiddlewareStack() {
 	)
 	// create a server
 	srv := http.NewServeMux()
+	srv.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
+		request.Header.Get(correlation_id.HeaderName)
+		writer.WriteHeader(http.StatusOK)
+	})
+
 	// apply the middlewares on the server
 	// note: this part is normally done on `http.ListenAndServe(":<serverPort>", stack.DecorateHandler(srv))`
 	h := stack.DecorateHandler(srv)

tripperware/correlation_id.go

@@ -10,7 +10,8 @@ import (
 
 // CorrelationId tripperware gets request id header if provided or generates a request id
 // It will add the request ID to request context
-func CorrelationId(config *correlation_id.Config) httpware.Tripperware {
+func CorrelationId(options ...correlation_id.Option) httpware.Tripperware {
+	config := correlation_id.GetConfig(options...)
 	return func(next http.RoundTripper) http.RoundTripper {
 		return httpware.RoundTripFunc(func(req *http.Request) (resp *http.Response, err error) {
 			if v, ok := req.Context().Value(config.HeaderName).(string); ok {