Add logging to /var/log for onboot containers

Signed-off-by: Avi Deitcher <avi@deitcher.net>

pkg/init/cmd/service/main.go

@@ -83,9 +83,9 @@ func main() {
 		command := os.Args[0]
 		switch {
 		case strings.Contains(command, "onboot"):
-			os.Exit(runcInit(onbootPath))
+			os.Exit(runcInit(onbootPath, "onboot"))
 		case strings.Contains(command, "onshutdown"):
-			os.Exit(runcInit(shutdownPath))
+			os.Exit(runcInit(shutdownPath, "shutdown"))
 		case strings.Contains(command, "containerd"):
 			systemInitCmd(ctx, []string{})
 			os.Exit(0)

pkg/init/cmd/service/runc.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"path"
 	"path/filepath"
 	"strconv"
 
@@ -13,9 +15,23 @@ import (
 
 const (
 	runcBinary = "/usr/bin/runc"
+	logDirBase = "/run/log/"
+	varLogDir  = "/var/log"
 )
 
-func runcInit(rootPath string) int {
+func dumpFile(w io.Writer, filePath string) error {
+	f, err := os.OpenFile(filePath, os.O_RDONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = io.Copy(w, f)
+
+	return err
+}
+
+func runcInit(rootPath, serviceType string) int {
 	// do nothing if the path does not exist
 	if _, err := os.Stat(rootPath); err != nil && os.IsNotExist(err) {
 		return 0
@@ -39,6 +55,13 @@ func runcInit(rootPath string) int {
 
 	status := 0
 
+	logDir := path.Join(logDirBase, serviceType)
+	varLogLink := path.Join(varLogDir, serviceType)
+
+	if err := os.MkdirAll(logDir, 0755); err != nil {
+		log.Fatalf("Cannot create log directory %s: %v", logDir, err)
+	}
+
 	for _, file := range files {
 		name := file.Name()
 		path := filepath.Join(rootPath, name)
@@ -52,8 +75,32 @@ func runcInit(rootPath string) int {
 		}
 		pidfile := filepath.Join(tmpdir, name)
 		cmd := exec.Command(runcBinary, "create", "--bundle", path, "--pid-file", pidfile, name)
-		cmd.Stdout = os.Stdout
+
-		cmd.Stderr = os.Stderr
+		// stream stdout and stderr to respective files
+		// ideally we want to use io.MultiWriter here, sending one stream to stdout/stderr, another to the files
+		// however, this hangs if we do, due to a runc bug, see https://github.com/opencontainers/runc/issues/1721#issuecomment-366315563
+		// once that is fixed, this can be cleaned up
+		stdoutFile := filepath.Join(logDir, serviceType+"."+name+".out.log")
+		stdout, err := os.OpenFile(stdoutFile, os.O_WRONLY|os.O_CREATE, 0644)
+		if err != nil {
+			log.Printf("Error opening stdout log file: %v", err)
+			status = 1
+			continue
+		}
+		defer stdout.Close()
+
+		stderrFile := filepath.Join(logDir, serviceType+"."+name+".err.log")
+		stderr, err := os.OpenFile(stderrFile, os.O_WRONLY|os.O_CREATE, 0644)
+		if err != nil {
+			log.Printf("Error opening stderr log file: %v", err)
+			status = 1
+			continue
+		}
+		defer stderr.Close()
+
+		cmd.Stdout = stdout
+		cmd.Stderr = stderr
+
 		if err := cmd.Run(); err != nil {
 			log.Printf("Error creating %s: %v", name, err)
 			status = 1
@@ -91,8 +138,9 @@ func runcInit(rootPath string) int {
 		}()
 
 		cmd = exec.Command(runcBinary, "start", name)
-		cmd.Stdout = os.Stdout
+		cmd.Stdout = stdout
-		cmd.Stderr = os.Stderr
+		cmd.Stderr = stderr
+
 		if err := cmd.Run(); err != nil {
 			log.Printf("Error starting %s: %v", name, err)
 			status = 1
@@ -103,9 +151,24 @@ func runcInit(rootPath string) int {
 
 		cleanup(path)
 		_ = os.Remove(pidfile)
+
+		// dump the log file outputs to os.Stdout/os.Stderr
+		if err = dumpFile(os.Stdout, stdoutFile); err != nil {
+			log.Printf("Error writing stdout of onboot service %s to console: %v", name, err)
+		}
+		if err = dumpFile(os.Stderr, stderrFile); err != nil {
+			log.Printf("Error writing stderr of onboot service %s to console: %v", name, err)
+		}
 	}
 
 	_ = os.RemoveAll(tmpdir)
 
+	// make sure the link exists from /var/log/onboot -> /run/log/onboot
+	if err := os.MkdirAll(varLogDir, 0755); err != nil {
+		log.Printf("Error creating secondary log directory %s: %v", varLogDir, err)
+	} else if err := os.Symlink(logDir, varLogLink); err != nil && !os.IsExist(err) {
+		log.Printf("Error creating symlink from %s to %s: %v", varLogLink, logDir, err)
+	}
+
 	return status
 }