basic logger

.gitignore

@@ -0,0 +1 @@
+vendor

Gopkg.toml

@@ -0,0 +1,34 @@
+# Gopkg.toml example
+#
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#   name = "github.com/x/y"
+#   version = "2.4.0"
+#
+# [prune]
+#   non-go = false
+#   go-tests = true
+#   unused-packages = true
+
+
+[[constraint]]
+  name = "github.com/satori/go.uuid"
+  version = "1.2.0"
+
+[prune]
+  go-tests = true
+  unused-packages = true

apicontext/context.go

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+package apicontext
+
+import (
+	"context"
+
+	uuid "github.com/satori/go.uuid"
+)
+
+type contextKey int
+
+const (
+	reqIDKey    contextKey = 0
+	clientIDKey contextKey = 1
+	userIDKey   contextKey = 2
+)
+
+// WithReqID returns a new Context that carries request ID
+func WithReqID(ctx context.Context) context.Context {
+	return context.WithValue(ctx, reqIDKey, uuid.NewV4().String())
+}
+
+// WithClientID returns a new Context that carries client ID
+func WithClientID(ctx context.Context, clientID uint) context.Context {
+	return context.WithValue(ctx, clientIDKey, clientID)
+}
+
+// WithUserID returns a new Context that carries user ID
+func WithUserID(ctx context.Context, userID uint) context.Context {
+	return context.WithValue(ctx, userIDKey, userID)
+}
+
+//ReqID returns the requestID from context.
+//Returns 0 if requestID is not set in context
+func ReqID(ctx context.Context) string {
+	reqID := ctx.Value(reqIDKey)
+	if reqID != nil {
+		return reqID.(string)
+	}
+	return ""
+}
+
+//ClientID returns the client_id of authorized client from context.
+//Returns 0 if client_id is not set in context
+func ClientID(ctx context.Context) uint {
+	clientID := ctx.Value(clientIDKey)
+	if clientID != nil {
+		return clientID.(uint)
+	}
+	return 0
+}
+
+//UserID returns user_id of authenticated user of a client from context.
+//Returns 0 if user_id is not set in context
+func UserID(ctx context.Context) uint {
+	userID := ctx.Value(userIDKey)
+	if userID != nil {
+		return userID.(uint)
+	}
+	return 0
+}

logger/logging.go

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+package logger
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"log-context/apicontext"
+	"runtime"
+)
+
+//Info logs with context
+func Info(ctx context.Context, msg string, v ...interface{}) {
+	ctxString := fmt.Sprintf("[%v:%v:%v] %v", apicontext.ReqID(ctx), apicontext.ClientID(ctx), apicontext.UserID(ctx), caller())
+	log.Printf("%v INFO: %v", ctxString, fmt.Sprintf(msg, v...))
+}
+
+//Error logs with context
+func Error(ctx context.Context, msg string, v ...interface{}) {
+	ctxString := fmt.Sprintf("[%v:%v:%v] %v", apicontext.ReqID(ctx), apicontext.ClientID(ctx), apicontext.UserID(ctx), caller())
+	log.Printf("%v ERROR: %v", ctxString, fmt.Sprintf(msg, v...))
+}
+
+//Debug logs with context
+func Debug(ctx context.Context, msg string, v ...interface{}) {
+	ctxString := fmt.Sprintf("[%v:%v:%v] %v", apicontext.ReqID(ctx), apicontext.ClientID(ctx), apicontext.UserID(ctx), caller())
+	log.Printf("%v DEBUG: %v", ctxString, fmt.Sprintf(msg, v...))
+}
+
+//to give you name of the file and line number from where logs are emitted
+func caller() string {
+	_, file, no, ok := runtime.Caller(2)
+	if ok {
+		short := file
+		for i := len(file) - 1; i > 0; i-- {
+			if file[i] == '/' {
+				short = file[i+1:]
+				break
+			}
+		}
+		file = short
+		return fmt.Sprintf("%v:%v ", file, no)
+	}
+	return "???:0 "
+}

server/main.go

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+package main
+
+import (
+	"context"
+	"log-context/apicontext"
+	"log-context/logger"
+)
+
+func main() {
+	ctx := apicontext.WithReqID(context.Background())
+	logger.Info(ctx, "test info log formatted with var %v, var %v ", 1, "two")
+	logger.Error(ctx, "test error log formatted with var %v, var %v ", 1, "two")
+	logger.Debug(ctx, "test debug log formatted with var %v, var %v ", 1, "two")
+}