Add context information to logger with logrus

Author: aperezg

cmd/gopherapi/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"log"
 	"net/http"
 	"os"
 	"strconv"
@@ -12,6 +11,8 @@ 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/modifying"
 	"github.com/friendsofgo/gopherapi/pkg/removing"
 	"github.com/friendsofgo/gopherapi/pkg/server"
@@ -40,8 +41,10 @@ func main() {
 		gophers = sample.Gophers
 	}
 
+	logger := log.NewLogger(hooks.NewServerInformationHook())
+
 	repo := inmem.NewRepository(gophers)
-	fetchingService := fetching.NewService(repo)
+	fetchingService := fetching.NewService(repo, logger)
 	addingService := adding.NewService(repo)
 	modifyingService := modifying.NewService(repo)
 	removingService := removing.NewService(repo)
@@ -58,5 +61,5 @@ func main() {
 	)
 
 	fmt.Println("The gopher server is on tap now:", httpAddr)
-	log.Fatal(http.ListenAndServe(httpAddr, s.Router()))
+	logger.Fatal(http.ListenAndServe(httpAddr, s.Router()))
 }

go.mod

@@ -3,4 +3,5 @@ module github.com/friendsofgo/gopherapi
 require (
 	github.com/gorilla/mux v1.7.0
 	github.com/joho/godotenv v1.3.0
+	github.com/sirupsen/logrus v1.4.2
 )

go.sum

@@ -1,4 +1,13 @@
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gorilla/mux v1.7.0 h1:tOSd0UKHQd6urX6ApfOn4XdBMY6Sh1MfxV3kmaazO+U=
 github.com/gorilla/mux v1.7.0/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
 github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
+github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

pkg/fetching/service.go

@@ -4,21 +4,23 @@ import (
 	"context"
 
 	gopher "github.com/friendsofgo/gopherapi/pkg"
+	"github.com/friendsofgo/gopherapi/pkg/log"
 )
 
 // Service provides fetching operations.
 type Service interface {
 	FetchGophers(ctx context.Context) ([]gopher.Gopher, error)
-	FetchGopherByID(ctx context.Context, ID string) (*gopher.Gopher, error)
+	FetchGopherByID(ctx context.Context, ID string) *gopher.Gopher
 }
 
 type service struct {
 	repository gopher.Repository
+	logger     *log.Logger
 }
 
 // NewService creates a fetching service with the necessary dependencies
-func NewService(repository gopher.Repository) Service {
-	return &service{repository}
+func NewService(repository gopher.Repository, logger *log.Logger) Service {
+	return &service{repository, logger}
 }
 
 // FetchGophers returns all gophers
@@ -27,6 +29,14 @@ func (s *service) FetchGophers(ctx context.Context) ([]gopher.Gopher, error) {
 }
 
 // FetchGopherByID returns a gopher
-func (s *service) FetchGopherByID(ctx context.Context, ID string) (*gopher.Gopher, error) {
-	return s.repository.FetchGopherByID(ctx, ID)
+func (s *service) FetchGopherByID(ctx context.Context, ID string) *gopher.Gopher {
+	g, err := s.repository.FetchGopherByID(ctx, ID)
+
+	// This error can be any error type of our repository
+	if err != nil {
+		s.logger.UnexpectedError(ctx, err)
+		return nil
+	}
+
+	return g
 }

pkg/log/hooks/server.go

@@ -0,0 +1,29 @@
+package hooks
+
+import (
+	"github.com/sirupsen/logrus"
+
+	"github.com/friendsofgo/gopherapi/pkg/server"
+)
+
+type serverHook struct{}
+
+func NewServerInformationHook() logrus.Hook {
+	return &serverHook{}
+}
+
+func (h *serverHook) Fire(entry *logrus.Entry) error {
+	ctx := entry.Context
+
+	hostname, _ := server.Name(ctx)
+	httpAddr, _ := server.HttpAddr(ctx)
+
+	entry.Data["hostname"] = hostname
+	entry.Data["httpAddr"] = httpAddr
+
+	return nil
+}
+
+func (h *serverHook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}

pkg/log/logger.go

@@ -0,0 +1,40 @@
+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)
+}

pkg/server/server.go

@@ -93,10 +93,10 @@ func (s *server) FetchGopher(w http.ResponseWriter, r *http.Request) {
 	ctx := s.createContext(r.Context())
 
 	vars := mux.Vars(r)
-	gopher, err := s.fetching.FetchGopherByID(ctx, vars["ID"])
+	gopher := s.fetching.FetchGopherByID(ctx, vars["ID"])
 	w.Header().Set("Content-Type", "application/json")
-	if err != nil {
-		w.WriteHeader(http.StatusNotFound) // We use not found for simplicity
+	if gopher == nil {
+		w.WriteHeader(http.StatusNotFound)
 		_ = json.NewEncoder(w).Encode("Gopher Not found")
 		return
 	}

pkg/storage/inmem/repository.go

@@ -69,7 +69,7 @@ func (r *gopherRepository) FetchGopherByID(ctx context.Context, ID string) (*gop
 		}
 	}
 
-	return nil, fmt.Errorf("The ID %s doesn't exist", ID)
+	return nil, fmt.Errorf("Error has ocurred while finding gopher %s", ID)
 }
 
 func (r *gopherRepository) checkIfExists(ctx context.Context, ID string) error {