TUN-8735: add managed/local log collection

## Summary
Adds a log collector for the managed/local runtimes.


Closes TUN-8735 TUN-8736

diagnostic/log_collector_host.go

@@ -0,0 +1,73 @@
+package diagnostic
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+const (
+	linuxManagedLogsPath  = "/var/log/cloudflared.err"
+	darwinManagedLogsPath = "/Library/Logs/com.cloudflare.cloudflared.err.log"
+)
+
+type HostLogCollector struct {
+	client HTTPClient
+}
+
+func NewHostLogCollector(client HTTPClient) *HostLogCollector {
+	return &HostLogCollector{
+		client,
+	}
+}
+
+func getServiceLogPath() (string, error) {
+	switch runtime.GOOS {
+	case "darwin":
+		{
+			path := darwinManagedLogsPath
+			if _, err := os.Stat(path); err == nil {
+				return path, nil
+			}
+
+			userHomeDir, err := os.UserHomeDir()
+			if err != nil {
+				return "", fmt.Errorf("error getting user home: %w", err)
+			}
+
+			return filepath.Join(userHomeDir, darwinManagedLogsPath), nil
+		}
+	case "linux":
+		{
+			return linuxManagedLogsPath, nil
+		}
+	default:
+		return "", ErrManagedLogNotFound
+	}
+}
+
+func (collector *HostLogCollector) Collect(ctx context.Context) (*LogInformation, error) {
+	logConfiguration, err := collector.client.GetLogConfiguration(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("error getting log configuration: %w", err)
+	}
+
+	if logConfiguration.uid == 0 {
+		path, err := getServiceLogPath()
+		if err != nil {
+			return nil, err
+		}
+
+		return NewLogInformation(path, false, false), nil
+	}
+
+	if logConfiguration.logFile != "" {
+		return NewLogInformation(logConfiguration.logFile, false, false), nil
+	} else if logConfiguration.logDirectory != "" {
+		return NewLogInformation(logConfiguration.logDirectory, false, true), nil
+	}
+
+	return nil, ErrMustNotBeEmpty
+}