improve logging for containers

Author: pfandzelter

cmd/manager/main.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
 	"os"
@@ -293,7 +294,7 @@ func (s *server) logsHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// parse request
-	var logs string
+	var logs io.Reader
 	name := r.URL.Query().Get("name")
 
 	if name == "" {
@@ -318,7 +319,13 @@ func (s *server) logsHandler(w http.ResponseWriter, r *http.Request) {
 
 	// return success
 	w.WriteHeader(http.StatusOK)
-	fmt.Fprint(w, logs)
+	// w.Header().Set("Content-Type", "text/plain")
+	_, err := io.Copy(w, logs)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		log.Println(err)
+		return
+	}
 }
 
 func (s *server) urlUploadHandler(w http.ResponseWriter, r *http.Request) {

pkg/docker/handler.go

@@ -2,6 +2,7 @@ package docker
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"fmt"
 	"io"
@@ -18,6 +19,7 @@ import (
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/client"
 	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/docker/pkg/stdcopy"
 	"github.com/google/uuid"
 )
 
@@ -359,33 +361,47 @@ func (dh *dockerHandler) Destroy() error {
 	return nil
 }
 
-func (dh *dockerHandler) Logs() (string, error) {
+func (dh *dockerHandler) Logs() (io.Reader, error) {
 	// get container logs
 	// docker logs <container>
-	var logs string
+	var logs bytes.Buffer
 	for _, container := range dh.containers {
 		l, err := dh.client.ContainerLogs(
 			context.Background(),
 			container,
 			types.ContainerLogsOptions{
 				ShowStdout: true,
 				ShowStderr: true,
+				Timestamps: true,
 			},
 		)
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
-		lstr, err := io.ReadAll(l)
+		var lstdout bytes.Buffer
+		var lstderr bytes.Buffer
+
+		_, err = stdcopy.StdCopy(&lstdout, &lstderr, l)
+
 		l.Close()
 
 		if err != nil {
-			return "", err
+			return nil, err
 		}
 
-		logs += string(lstr)
-		logs += "\n"
+		// add a prefix to each line
+		// function=<function> handler=<handler> <line>
+		scanner := bufio.NewScanner(&lstdout)
+
+		for scanner.Scan() {
+			logs.WriteString(fmt.Sprintf("function=%s handler=%s %s\n", dh.name, container, scanner.Text()))
+		}
+
+		if err := scanner.Err(); err != nil {
+			return nil, err
+		}
 	}
 
-	return logs, nil
+	return &logs, nil
 }

pkg/manager/manager.go

@@ -40,7 +40,7 @@ type Handler interface {
 	IPs() []string
 	Start() error
 	Destroy() error
-	Logs() (string, error)
+	Logs() (io.Reader, error)
 }
 
 func New(id string, rproxyListenAddress string, rproxyPort map[string]int, rproxyConfigPort int, tfBackend Backend) *ManagementService {
@@ -183,28 +183,32 @@ func (ms *ManagementService) createFunction(name string, env string, threads int
 	return name, nil
 }
 
-func (ms *ManagementService) Logs() (string, error) {
+func (ms *ManagementService) Logs() (io.Reader, error) {
 
-	var logs string
+	var logs bytes.Buffer
 
 	for name := range ms.functionHandlers {
 		l, err := ms.LogsFunction(name)
 		if err != nil {
-			return "", err
+			return nil, err
+		}
+
+		_, err = io.Copy(&logs, l)
+		if err != nil {
+			return nil, err
 		}
 
-		logs += l
-		logs += "\n"
+		logs.WriteString("\n")
 	}
 
-	return logs, nil
+	return &logs, nil
 }
 
-func (ms *ManagementService) LogsFunction(name string) (string, error) {
+func (ms *ManagementService) LogsFunction(name string) (io.Reader, error) {
 
 	fh, ok := ms.functionHandlers[name]
 	if !ok {
-		return "", fmt.Errorf("function %s not found", name)
+		return nil, fmt.Errorf("function %s not found", name)
 	}
 
 	return fh.Logs()