runtime_vm: Implement the ReopenContainerLog function

littlejawa · littlejawa · commit 7b5b07cb3e19 · 2025-09-04T09:44:28.000+02:00
This commit implements the ReopenContainerLog function.
This fixes an issue where kata container logs could not be rotated.

This required duplicating part of the createContainerIO function, so I am moving
this in its own subfunction for reuse.

Signed-off-by: Julien Ropé &lt;jrope@redhat.com&gt;
diff --git a/internal/oci/runtime_vm.go b/internal/oci/runtime_vm.go
@@ -942,16 +942,35 @@ func (r *runtimeVM) createContainerIO(ctx context.Context, c *Container, cioOpts
 		}
 	}()
 
-	f, err := os.OpenFile(c.LogPath(), os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o600)
+	stdout, stderr, err := r.createContainerLoggers(ctx, c.LogPath())
 	if err != nil {
 		return nil, err
 	}
 
+	containerIO.AddOutput(c.LogPath(), stdout, stderr)
+	containerIO.Pipe()
+
+	r.Lock()
+	r.ctrs[c.ID()] = containerInfo{
+		cio: containerIO,
+	}
+	r.Unlock()
+
+	return containerIO, nil
+}
+
+// createContainerLoggers creates container loggers and return write closer for stdout and stderr.
+func (r *runtimeVM) createContainerLoggers(ctx context.Context, logPath string) (stdout, stderr io.WriteCloser, err error) {
+	f, err := os.OpenFile(logPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o600)
+	if err != nil {
+		return nil, nil, err
+	}
+
 	var stdoutCh, stderrCh <-chan struct{}
 
 	wc := cioutil.NewSerialWriteCloser(f)
-	stdout, stdoutCh := cio.NewCRILogger(c.LogPath(), wc, cio.Stdout, -1)
-	stderr, stderrCh := cio.NewCRILogger(c.LogPath(), wc, cio.Stderr, -1)
+	stdout, stdoutCh = cio.NewCRILogger(logPath, wc, cio.Stdout, -1)
+	stderr, stderrCh = cio.NewCRILogger(logPath, wc, cio.Stderr, -1)
 
 	go func() {
 		if stdoutCh != nil {
@@ -962,20 +981,11 @@ func (r *runtimeVM) createContainerIO(ctx context.Context, c *Container, cioOpts
 			<-stderrCh
 		}
 
-		log.Debugf(ctx, "Finish redirecting log file %q, closing it", c.LogPath())
+		log.Debugf(ctx, "Finish redirecting log file %q, closing it", logPath)
 		f.Close()
 	}()
 
-	containerIO.AddOutput(c.LogPath(), stdout, stderr)
-	containerIO.Pipe()
-
-	r.Lock()
-	r.ctrs[c.ID()] = containerInfo{
-		cio: containerIO,
-	}
-	r.Unlock()
-
-	return containerIO, nil
+	return stdout, stderr, nil
 }
 
 // PauseContainer pauses a container.
@@ -1228,6 +1238,29 @@ func (r *runtimeVM) ReopenContainerLog(ctx context.Context, c *Container) error
 	log.Debugf(ctx, "RuntimeVM.ReopenContainerLog() start")
 	defer log.Debugf(ctx, "RuntimeVM.ReopenContainerLog() end")
 
+	r.Lock()
+	cInfo, ok := r.ctrs[c.ID()]
+	r.Unlock()
+
+	if !ok {
+		return errors.New("could not retrieve container information")
+	}
+
+	// Create new container logger and replace the existing ones.
+	stdoutWC, stderrWC, err := r.createContainerLoggers(ctx, c.LogPath())
+	if err != nil {
+		return err
+	}
+
+	oldStdoutWC, oldStderrWC := cInfo.cio.AddOutput(c.LogPath(), stdoutWC, stderrWC)
+	if oldStdoutWC != nil {
+		oldStdoutWC.Close()
+	}
+
+	if oldStderrWC != nil {
+		oldStderrWC.Close()
+	}
+
 	return nil
 }
 
