Refactor with dependency inversion of the logger

Author: aperezg

cmd/gopherapi/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 	"net/http"
 	"os"
 	"strconv"
@@ -11,8 +12,7 @@ import (
 	gopher "github.com/friendsofgo/gopherapi/pkg"
 	"github.com/friendsofgo/gopherapi/pkg/adding"
 	"github.com/friendsofgo/gopherapi/pkg/fetching"
-	"github.com/friendsofgo/gopherapi/pkg/log"
-	"github.com/friendsofgo/gopherapi/pkg/log/hooks"
+	"github.com/friendsofgo/gopherapi/pkg/log/logrus"
 	"github.com/friendsofgo/gopherapi/pkg/modifying"
 	"github.com/friendsofgo/gopherapi/pkg/removing"
 	"github.com/friendsofgo/gopherapi/pkg/server"
@@ -41,7 +41,7 @@ func main() {
 		gophers = sample.Gophers
 	}
 
-	logger := log.NewLogger(hooks.NewServerInformationHook())
+	logger := logrus.NewLogger()
 
 	repo := inmem.NewRepository(gophers)
 	fetchingService := fetching.NewService(repo, logger)
@@ -61,5 +61,5 @@ func main() {
 	)
 
 	fmt.Println("The gopher server is on tap now:", httpAddr)
-	logger.Fatal(http.ListenAndServe(httpAddr, s.Router()))
+	log.Fatal(http.ListenAndServe(httpAddr, s.Router()))
 }

pkg/fetching/service.go

@@ -15,11 +15,11 @@ type Service interface {
 
 type service struct {
 	repository gopher.Repository
-	logger     *log.Logger
+	logger     log.Logger
 }
 
 // NewService creates a fetching service with the necessary dependencies
-func NewService(repository gopher.Repository, logger *log.Logger) Service {
+func NewService(repository gopher.Repository, logger log.Logger) Service {
 	return &service{repository, logger}
 }
 

pkg/log/hooks/server.go

@@ -2,39 +2,10 @@ package log
 
 import (
 	"context"
-
-	"github.com/sirupsen/logrus"
-)
-
-// Event stores messages to log later, from our standard interface
-type Event struct {
-	id      string
-	message string
-}
-
-// Logger centralize log messages format
-type Logger struct {
-	*logrus.Logger
-}
-
-// NewLogger initializes the standard logger
-func NewLogger(hooks ...logrus.Hook) *Logger {
-	logger := logrus.New()
-
-	for _, hook := range hooks {
-		logger.AddHook(hook)
-	}
-
-	return &Logger{logger}
-}
-
-// Declare variables to store log messages as new Events
-var (
-	unexpectedErrorMessage = Event{"01DK2XFX9PQ85ZPZ5CP68P108Y", "Unexpected error: %v"}
 )
 
-// ElementNotFound is a standard error message for elements not found
-func (l *Logger) UnexpectedError(ctx context.Context, err error) {
-	l.WithContext(ctx).WithField("logid", unexpectedErrorMessage.id).
-		Errorf(unexpectedErrorMessage.message, err)
+// Logger determine the way to centralize log messages format
+type Logger interface {
+	// UnexpectedError is a standard error message for unexpected errors
+	UnexpectedError(ctx context.Context, err error)
 }

pkg/log/logger.go

@@ -0,0 +1,47 @@
+package logrus
+
+import (
+	"context"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/friendsofgo/gopherapi/pkg/log"
+	"github.com/friendsofgo/gopherapi/pkg/server"
+)
+
+// Event stores messages to log later, from our standard interface
+type Event struct {
+	id      string
+	message string
+}
+
+// Logger centralize log messages format
+type logger struct {
+	*logrus.Logger
+}
+
+// NewLogger initializes the standard logger
+func NewLogger(hooks ...logrus.Hook) log.Logger {
+	return &logger{logrus.New()}
+}
+
+// Declare variables to store log messages as new Events
+var (
+	unexpectedErrorMessage = Event{"01DK2XFX9PQ85ZPZ5CP68P108Y", "Unexpected error: %v"}
+)
+
+func (l *logger) UnexpectedError(ctx context.Context, err error) {
+	l.WithDefaultFields(ctx).WithField("logid", unexpectedErrorMessage.id).
+		Errorf(unexpectedErrorMessage.message, err)
+}
+
+func (l *logger) WithDefaultFields(ctx context.Context) *logrus.Entry {
+	hostname, _ := server.Name(ctx)
+	httpAddr, _ := server.HttpAddr(ctx)
+
+	return l.WithFields(logrus.Fields{
+		"hostname": hostname,
+		"httpAddr": httpAddr,
+	})
+
+}