Feature/log mdc (#24)

* feat: adds custom logger package
* feat: adds request headers as logging fields in slog
* feat: replaces log with slog in api request flow

---------

Signed-off-by: Amit Singh <[email protected]>

.golangci.yml

@@ -1,3 +1,8 @@
 issues:
   exclude:
-    - (.*)_test\.go$
+    - (.*)_test\.go$
+
+linters-settings:
+  errcheck:
+    exclude-functions:
+    - (*Logger).Sync

acceptance/acceptance_suite_test.go

@@ -31,14 +31,14 @@ func TestSourceScore(t *testing.T) {
 		log.Fatalf("application not running on port: %s", serverPort)
 	}
 
-	baseUrl = "http://" + helpers.LOCALHOST + ":" + serverPort
+	baseUrl = "http://" + helpers.Localhost + ":" + serverPort
 
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "SourceScore Acceptance Test Suite")
 }
 
 func isLocalPortOpen(port string) bool {
-	address := net.JoinHostPort(helpers.LOCALHOST, port)
+	address := net.JoinHostPort(helpers.Localhost, port)
 	conn, err := net.DialTimeout("tcp", address, 2*time.Second)
 	if err != nil {
 		return false

main.go

@@ -2,23 +2,48 @@ package main
 
 import (
 	"log"
+	"log/slog"
+	"os"
 
 	"github.com/gin-gonic/gin"
 
 	"source-score/pkg/api"
 	"source-score/pkg/conf"
+	"source-score/pkg/helpers"
+	"source-score/pkg/logger"
 )
 
 func main() {
+	// initialize the config
 	conf.LoadConfig()
 
+	// initialize the logger
+	slog.SetDefault(
+		slog.New(&logger.ContextHandler{
+			Handler: slog.NewJSONHandler(os.Stdout, nil),
+		}),
+	)
+
+	// initialize the server
+	loggerOpts := api.GinServerOptions{
+		Middlewares: []api.MiddlewareFunc{
+			// function to add request headers to log fields
+			func(c *gin.Context) {
+				for _, fieldKey := range helpers.ApiReqLogFields {
+					fieldVal := c.Request.Header.Get(fieldKey)
+					logger.AppendGinCtx(c, slog.String(fieldKey, fieldVal))
+				}
+			},
+		},
+	}
+
 	server := gin.Default()
-	api.RegisterHandlers(server, api.NewRouter())
+	api.RegisterHandlersWithOptions(server, api.NewRouter(), loggerOpts)
 
 	err := server.Run()
 	if err != nil {
-		log.Fatalf("failed to start the server: %s\n", err)
+		log.Fatalf("failed to start the server : %s\n", err.Error())
 	} else {
 		log.Println("Server is up and running!")
 	}
-}
+}

pkg/api/router.go

@@ -1,7 +1,7 @@
 package api
 
 import (
-	"log"
+	"log/slog"
 	"net/http"
 	"source-score/pkg/handlers"
 
@@ -26,23 +26,23 @@ func (r *router) CreateSource(ctx *gin.Context) {
 		_ = ctx.AbortWithError(http.StatusBadRequest, err)
 		return
 	}
-	log.Println("unimplemented")
+	slog.InfoContext(ctx, "unimplemented")
 }
 
 func (r *router) DeleteSource(ctx *gin.Context, uriDigest string) {
-	log.Println("unimplemented")
+	slog.InfoContext(ctx, "unimplemented")
 }
 
 func (r *router) GetSource(ctx *gin.Context, uriDigest string) {
-	log.Println("unimplemented")
+	slog.InfoContext(ctx, "unimplemented")
 }
 
 func (r *router) UpdateSource(ctx *gin.Context, uriDigest string) {
-	log.Println("unimplemented")
+	slog.InfoContext(ctx, "unimplemented")
 }
 
 func (r *router) GetPing(ctx *gin.Context) {
-	message := r.pingHandler.GetPing()
+	message := r.pingHandler.GetPing(ctx)
 
 	ctx.JSON(http.StatusOK, gin.H{"data": message})
 }

pkg/domain/source/source_repository.go

@@ -4,7 +4,8 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
-	"log"
+	"fmt"
+	"log/slog"
 
 	"source-score/pkg/api"
 	"source-score/pkg/db/cnpg"
@@ -22,7 +23,10 @@ func NewSourceRepository(ctx context.Context, client *cnpg.Client) *SourceReposi
 
 func (sr *SourceRepository) DeleteSourceByUriDigest(ctx context.Context, source *api.Source) error {
 	result := sr.client.Delete(ctx, source)
-	log.Printf("%d rows affected\n", result.RowsAffected)
+	slog.InfoContext(
+		ctx,
+		fmt.Sprintf("%d rows affected\n", result.RowsAffected),
+	)
 
 	return result.Error
 }
@@ -56,7 +60,10 @@ func (sr *SourceRepository) PutSource(ctx context.Context, sourceInput *api.Sour
 	}
 
 	result := sr.client.Create(ctx, source)
-	log.Printf("%d rows affected\n", result.RowsAffected)
+	slog.InfoContext(
+		ctx,
+		fmt.Sprintf("%d rows affected\n", result.RowsAffected),
+	)
 
 	return result.Error
 }
@@ -76,7 +83,10 @@ func (sr *SourceRepository) UpdateSourceByUriDigest(ctx context.Context, sourceI
 	source.Tags = sourceInput.Tags
 
 	result = sr.client.Update(ctx, source)
-	log.Printf("%d rows affected\n", result.RowsAffected)
+	slog.InfoContext(
+		ctx,
+		fmt.Sprintf("%d rows affected\n", result.RowsAffected),
+	)
 
 	return result.Error
 }

pkg/handlers/ping.go

@@ -1,5 +1,9 @@
 package handlers
 
+import (
+	"context"
+)
+
 type PingHandler struct {
 	message string
 }
@@ -10,6 +14,6 @@ func NewPingHandler() *PingHandler {
 	}
 }
 
-func (ph PingHandler) GetPing() string {
+func (ph PingHandler) GetPing(ctx context.Context) string {
 	return ph.message
 }

pkg/helpers/constants.go

@@ -1,5 +1,12 @@
 package helpers
 
 const (
-	LOCALHOST = "127.0.0.1"
+	Localhost       = "127.0.0.1"
+	RequestIdHeader = "X-Request-ID"
 )
+
+var (
+	ApiReqLogFields = []string {
+		RequestIdHeader,
+	}
+)

pkg/logger/logger.go

@@ -0,0 +1,40 @@
+package logger
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/gin-gonic/gin"
+)
+
+const (
+	slogFields = "slog_fields"
+)
+
+type ContextHandler struct {
+	slog.Handler
+}
+
+// Handle adds contextual attributes to the Record before calling the underlying handler
+func (h ContextHandler) Handle(ctx context.Context, r slog.Record) error {
+	if attrs, ok := ctx.Value(slogFields).([]slog.Attr); ok {
+		for _, v := range attrs {
+			r.AddAttrs(v)
+		}
+	}
+
+	return h.Handler.Handle(ctx, r)
+}
+
+// AppendGinCtx adds an slog attribute to the provided context so that it will be included
+// in any Record created with such context
+func AppendGinCtx(parent *gin.Context, attr slog.Attr) {
+	if v, ok := parent.Value(slogFields).([]slog.Attr); ok {
+		v = append(v, attr)
+		parent.Set(slogFields, v)
+	}
+
+	v := []slog.Attr{}
+	v = append(v, attr)
+	parent.Set(slogFields, v)
+}