Add simple log viewer in web frontend

internal/api/log.go

@@ -0,0 +1,167 @@
+// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
+// All rights reserved. This file is part of cc-backend.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+package api
+
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os/exec"
+	"regexp"
+	"strconv"
+
+	"github.com/ClusterCockpit/cc-backend/internal/config"
+	"github.com/ClusterCockpit/cc-backend/internal/repository"
+	cclog "github.com/ClusterCockpit/cc-lib/v2/ccLogger"
+	"github.com/ClusterCockpit/cc-lib/v2/schema"
+	"github.com/gorilla/mux"
+)
+
+type LogEntry struct {
+	Timestamp string `json:"timestamp"`
+	Priority  int    `json:"priority"`
+	Message   string `json:"message"`
+	Unit      string `json:"unit"`
+}
+
+var safePattern = regexp.MustCompile(`^[a-zA-Z0-9 :\-\.]+$`)
+
+func (api *RestAPI) getJournalLog(rw http.ResponseWriter, r *http.Request) {
+	user := repository.GetUserFromContext(r.Context())
+	if !user.HasRole(schema.RoleAdmin) {
+		handleError(fmt.Errorf("only admins are allowed to view logs"), http.StatusForbidden, rw)
+		return
+	}
+
+	since := r.URL.Query().Get("since")
+	if since == "" {
+		since = "1 hour ago"
+	}
+	if !safePattern.MatchString(since) {
+		handleError(fmt.Errorf("invalid 'since' parameter"), http.StatusBadRequest, rw)
+		return
+	}
+
+	lines := 200
+	if l := r.URL.Query().Get("lines"); l != "" {
+		n, err := strconv.Atoi(l)
+		if err != nil || n < 1 {
+			handleError(fmt.Errorf("invalid 'lines' parameter"), http.StatusBadRequest, rw)
+			return
+		}
+		if n > 1000 {
+			n = 1000
+		}
+		lines = n
+	}
+
+	unit := config.Keys.SystemdUnit
+	if unit == "" {
+		unit = "clustercockpit"
+	}
+
+	args := []string{
+		"--output=json",
+		"--no-pager",
+		fmt.Sprintf("-n %d", lines),
+		fmt.Sprintf("--since=%s", since),
+		fmt.Sprintf("-u %s", unit),
+	}
+
+	if level := r.URL.Query().Get("level"); level != "" {
+		n, err := strconv.Atoi(level)
+		if err != nil || n < 0 || n > 7 {
+			handleError(fmt.Errorf("invalid 'level' parameter (must be 0-7)"), http.StatusBadRequest, rw)
+			return
+		}
+		args = append(args, fmt.Sprintf("--priority=%d", n))
+	}
+
+	if search := r.URL.Query().Get("search"); search != "" {
+		if !safePattern.MatchString(search) {
+			handleError(fmt.Errorf("invalid 'search' parameter"), http.StatusBadRequest, rw)
+			return
+		}
+		args = append(args, fmt.Sprintf("--grep=%s", search))
+	}
+
+	cmd := exec.CommandContext(r.Context(), "journalctl", args...)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		handleError(fmt.Errorf("failed to create pipe: %w", err), http.StatusInternalServerError, rw)
+		return
+	}
+
+	if err := cmd.Start(); err != nil {
+		handleError(fmt.Errorf("failed to start journalctl: %w", err), http.StatusInternalServerError, rw)
+		return
+	}
+
+	entries := make([]LogEntry, 0, lines)
+	scanner := bufio.NewScanner(stdout)
+	for scanner.Scan() {
+		var raw map[string]any
+		if err := json.Unmarshal(scanner.Bytes(), &raw); err != nil {
+			continue
+		}
+
+		priority := 6 // default info
+		if p, ok := raw["PRIORITY"]; ok {
+			switch v := p.(type) {
+			case string:
+				if n, err := strconv.Atoi(v); err == nil {
+					priority = n
+				}
+			case float64:
+				priority = int(v)
+			}
+		}
+
+		msg := ""
+		if m, ok := raw["MESSAGE"]; ok {
+			if s, ok := m.(string); ok {
+				msg = s
+			}
+		}
+
+		ts := ""
+		if t, ok := raw["__REALTIME_TIMESTAMP"]; ok {
+			if s, ok := t.(string); ok {
+				ts = s
+			}
+		}
+
+		unitName := ""
+		if u, ok := raw["_SYSTEMD_UNIT"]; ok {
+			if s, ok := u.(string); ok {
+				unitName = s
+			}
+		}
+
+		entries = append(entries, LogEntry{
+			Timestamp: ts,
+			Priority:  priority,
+			Message:   msg,
+			Unit:      unitName,
+		})
+	}
+
+	if err := cmd.Wait(); err != nil {
+		// journalctl returns exit code 1 when --grep matches nothing
+		if len(entries) == 0 {
+			cclog.Debugf("journalctl exited with: %v", err)
+		}
+	}
+
+	rw.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(rw).Encode(entries); err != nil {
+		cclog.Errorf("Failed to encode log entries: %v", err)
+	}
+}
+
+func (api *RestAPI) MountLogAPIRoutes(r *mux.Router) {
+	r.HandleFunc("/logs/", api.getJournalLog).Methods(http.MethodGet)
+}

internal/config/config.go

@@ -71,6 +71,9 @@ type ProgramConfig struct {
 
 	// If exists, will enable dynamic zoom in frontend metric plots using the configured values
 	EnableResampling *ResampleConfig `json:"resampling"`
+
+	// Systemd unit name for log viewer (default: "clustercockpit")
+	SystemdUnit string `json:"systemd-unit"`
 }
 
 type ResampleConfig struct {

internal/routerConfig/routes.go

@@ -50,6 +50,7 @@ var routes []Route = []Route{
 	{"/monitoring/status/{cluster}", "monitoring/status.tmpl", "<ID> Dashboard - ClusterCockpit", false, setupClusterStatusRoute},
 	{"/monitoring/status/detail/{cluster}", "monitoring/status.tmpl", "Status of <ID> - ClusterCockpit", false, setupClusterDetailRoute},
 	{"/monitoring/dashboard/{cluster}", "monitoring/dashboard.tmpl", "<ID> Dashboard - ClusterCockpit", false, setupDashboardRoute},
+	{"/monitoring/logs", "monitoring/logs.tmpl", "Logs - ClusterCockpit", false, func(i InfoType, r *http.Request) InfoType { return i }},
 }
 
 func setupHomeRoute(i InfoType, r *http.Request) InfoType {