Make debug log file name configurable

This is a breaking change if you're using --debug-log-dir.
The fix is to replace it with --debug-log and add a '/' at
the end:
  --debug-log-dir=/tmp/runsc ==> --debug-log=/tmp/runsc/

PiperOrigin-RevId: 216761212
Change-Id: I244270a0a522298c48115719fa08dad55e34ade1

6 files changed, 35 insertions, 26 deletions

diff --git a/README.md b/README.md
index d85948ce5..a4fca1f62 100644
--- a/README.md
+++ b/README.md
@@ -297,7 +297,7 @@ Docker configuration (`/etc/docker/daemon.json`):
         "runsc": {
             "path": "/usr/local/bin/runsc",
             "runtimeArgs": [
-                "--debug-log-dir=/tmp/runsc",
+                "--debug-log=/tmp/runsc/",
                 "--debug",
                 "--strace"
             ]
diff --git a/runsc/boot/config.go b/runsc/boot/config.go
index cd977c8a5..41af084b9 100644
--- a/runsc/boot/config.go
+++ b/runsc/boot/config.go
@@ -160,9 +160,8 @@ type Config struct {
 	// LogFormat is the log format, "text" or "json".
 	LogFormat string
 
-	// DebugLogDir is the directory to log debug information to, if not
-	// empty.
-	DebugLogDir string
+	// DebugLog is the path to log debug information to, if not empty.
+	DebugLog string
 
 	// FileAccess indicates how the filesystem is accessed.
 	FileAccess FileAccessType
@@ -217,7 +216,7 @@ func (c *Config) ToFlags() []string {
 		"--debug=" + strconv.FormatBool(c.Debug),
 		"--log=" + c.LogFilename,
 		"--log-format=" + c.LogFormat,
-		"--debug-log-dir=" + c.DebugLogDir,
+		"--debug-log=" + c.DebugLog,
 		"--file-access=" + c.FileAccess.String(),
 		"--overlay=" + strconv.FormatBool(c.Overlay),
 		"--network=" + c.Network.String(),
diff --git a/runsc/main.go b/runsc/main.go
index 16d30f7a0..27aec1cd9 100644
--- a/runsc/main.go
+++ b/runsc/main.go
@@ -45,10 +45,10 @@ var (
 	// system that are not covered by the runtime spec.
 
 	// Debugging flags.
-	debugLogDir = flag.String("debug-log-dir", "", "additional location for logs. It creates individual log files per command")
-	logPackets  = flag.Bool("log-packets", false, "enable network packet logging")
-	logFD       = flag.Int("log-fd", -1, "file descriptor to log to.  If set, the 'log' flag is ignored.")
-	debugLogFD  = flag.Int("debug-log-fd", -1, "file descriptor to write debug logs to.  If set, the 'debug-log-dir' flag is ignored.")
+	debugLog   = flag.String("debug-log", "", "additional location for logs. If it ends with '/', log files are created inside the directory with default names. The following variables are available: %TIMESTAMP%, %COMMAND%.")
+	logPackets = flag.Bool("log-packets", false, "enable network packet logging")
+	logFD      = flag.Int("log-fd", -1, "file descriptor to log to.  If set, the 'log' flag is ignored.")
+	debugLogFD = flag.Int("debug-log-fd", -1, "file descriptor to write debug logs to.  If set, the 'debug-log-dir' flag is ignored.")
 
 	// Debugging flags: strace related
 	strace         = flag.Bool("strace", false, "enable strace")
@@ -131,7 +131,7 @@ func main() {
 		Debug:          *debug,
 		LogFilename:    *logFilename,
 		LogFormat:      *logFormat,
-		DebugLogDir:    *debugLogDir,
+		DebugLog:       *debugLog,
 		FileAccess:     fsAccess,
 		Overlay:        *overlay,
 		Network:        netType,
@@ -195,13 +195,10 @@ func main() {
 		}
 
 		e = log.MultiEmitter{e, log.GoogleEmitter{&log.Writer{Next: f}}}
-	} else if *debugLogDir != "" {
-		if err := os.MkdirAll(*debugLogDir, 0775); err != nil {
-			cmd.Fatalf("error creating dir %q: %v", *debugLogDir, err)
-		}
-		f, err := specutils.DebugLogFile(*debugLogDir, subcommand)
+	} else if *debugLog != "" {
+		f, err := specutils.DebugLogFile(*debugLog, subcommand)
 		if err != nil {
-			cmd.Fatalf("error opening debug log file in %q: %v", *debugLogDir, err)
+			cmd.Fatalf("error opening debug log file in %q: %v", *debugLog, err)
 		}
 		e = log.MultiEmitter{e, log.GoogleEmitter{&log.Writer{Next: f}}}
 	}
diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go
index 37a3efd09..a0de4a175 100644
--- a/runsc/sandbox/sandbox.go
+++ b/runsc/sandbox/sandbox.go
@@ -291,10 +291,10 @@ func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bund
 		cmd.Args = append(cmd.Args, "--log-fd="+strconv.Itoa(nextFD))
 		nextFD++
 	}
-	if conf.DebugLogDir != "" {
-		debugLogFile, err := specutils.DebugLogFile(conf.DebugLogDir, "boot")
+	if conf.DebugLog != "" {
+		debugLogFile, err := specutils.DebugLogFile(conf.DebugLog, "boot")
 		if err != nil {
-			return fmt.Errorf("error opening debug log file in %q: %v", conf.DebugLogDir, err)
+			return fmt.Errorf("error opening debug log file in %q: %v", conf.DebugLog, err)
 		}
 		defer debugLogFile.Close()
 		cmd.ExtraFiles = append(cmd.ExtraFiles, debugLogFile)
diff --git a/runsc/specutils/specutils.go b/runsc/specutils/specutils.go
index ac017ba2d..6b3e52021 100644
--- a/runsc/specutils/specutils.go
+++ b/runsc/specutils/specutils.go
@@ -351,12 +351,25 @@ func WaitForReady(pid int, timeout time.Duration, ready func() (bool, error)) er
 	return backoff.Retry(op, b)
 }
 
-// DebugLogFile opens a file in logDir based on the timestamp and subcommand
-// for writing.
-func DebugLogFile(logDir, subcommand string) (*os.File, error) {
-	// Format: <debug-log-dir>/runsc.log.<yyyymmdd-hhmmss.uuuuuu>.<command>
-	filename := fmt.Sprintf("runsc.log.%s.%s", time.Now().Format("20060102-150405.000000"), subcommand)
-	return os.OpenFile(filepath.Join(logDir, filename), os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0664)
+// DebugLogFile opens a log file using 'logPattern' as location. If 'logPattern'
+// ends with '/', it's used as a directory with default file name.
+// 'logPattern' can contain variables that are substitued:
+//   - %TIMESTAMP%: is replaced with a timestamp using the following format:
+//			<yyyymmdd-hhmmss.uuuuuu>
+//	 - %COMMAND%: is replaced with 'command'
+func DebugLogFile(logPattern, command string) (*os.File, error) {
+	if strings.HasSuffix(logPattern, "/") {
+		// Default format: <debug-log>/runsc.log.<yyyymmdd-hhmmss.uuuuuu>.<command>
+		logPattern += "runsc.log.%TIMESTAMP%.%COMMAND%"
+	}
+	logPattern = strings.Replace(logPattern, "%TIMESTAMP%", time.Now().Format("20060102-150405.000000"), -1)
+	logPattern = strings.Replace(logPattern, "%COMMAND%", command, -1)
+
+	dir := filepath.Dir(logPattern)
+	if err := os.MkdirAll(dir, 0775); err != nil {
+		return nil, fmt.Errorf("error creating dir %q: %v", dir, err)
+	}
+	return os.OpenFile(logPattern, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0664)
 }
 
 // Mount creates the mount point and calls Mount with the given flags.
diff --git a/runsc/test/install.sh b/runsc/test/install.sh
index c110d96f9..c239588d4 100755
--- a/runsc/test/install.sh
+++ b/runsc/test/install.sh
@@ -75,7 +75,7 @@ if [[ ${uninstall} == 0 ]]; then
   mkdir -p "${logdir}"
   sudo -n chmod a+wx "${logdir}"
 
-  declare -r args="--debug-log-dir "${logdir}" --debug --strace --log-packets"
+  declare -r args="--debug-log '${logdir}/' --debug --strace --log-packets"
   sudo -n "${dockercfg}" runtime-add "${runtime}" "${runsc}" ${args}
   sudo -n "${dockercfg}" runtime-add "${runtime}"-kvm "${runsc}" --platform=kvm ${args}
   sudo -n "${dockercfg}" runtime-add "${runtime}"-hostnet "${runsc}" --network=host ${args}