From 7c243a8e8bf610fefac70ec21329a4bc72ba018b Mon Sep 17 00:00:00 2001
From: David Scott <dave@recoil.org>
Date: Fri, 13 Jul 2018 11:43:48 +0100
Subject: [PATCH] pkg/init: only create /var/log/onboot symlink if not using
 memlogd

When logging directly to files (the not-using-memlogd case) the onboot
services must log to /run/log because /var/log might be overmounted
by a persistent disk. Therefore we create a symlink at the end of
the onboot section.

When logging via memlogd, all logs are buffered until a logwrite service
starts, so no symlink is needed.

Signed-off-by: David Scott <dave.scott@docker.com>
---
 pkg/init/cmd/service/logging.go | 16 ++++++++++++++++
 pkg/init/cmd/service/runc.go    |  6 +-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/pkg/init/cmd/service/logging.go b/pkg/init/cmd/service/logging.go
index 820465bc8..ad6c0bd12 100644
--- a/pkg/init/cmd/service/logging.go
+++ b/pkg/init/cmd/service/logging.go
@@ -29,6 +29,7 @@ type Log interface {
 	Path(string) string                  // Path of the log file (may be a FIFO)
 	Open(string) (io.WriteCloser, error) // Opens a log stream
 	Dump(string)                         // Copies logs to the console
+	Symlink(string)                      // Symlinks to the log directory (if there is one)
 }
 
 // GetLog returns the log destination we should use.
@@ -82,6 +83,16 @@ func (f *fileLog) Dump(n string) {
 	}
 }
 
+// Symlinks to the log directory. This is useful if we are logging directly to tmpfs and now need to symlink from a permanent disk.
+func (f *fileLog) Symlink(path string) {
+	parent := filepath.Dir(path)
+	if err := os.MkdirAll(parent, 0755); err != nil {
+		log.Printf("Error creating secondary log directory %s: %v", parent, err)
+	} else if err := os.Symlink(f.dir, path); err != nil && !os.IsExist(err) {
+		log.Printf("Error creating symlink from %s to %s: %v", path, f.dir, err)
+	}
+}
+
 type remoteLog struct {
 	fifoDir string
 }
@@ -164,6 +175,11 @@ func (r *remoteLog) Dump(n string) {
 	}
 }
 
+// Symlinks to the log directory. This is a no-op because there is no log directory.
+func (r *remoteLog) Symlink(path string) {
+	return
+}
+
 func sendToLogger(name string, fd int) error {
 	var ctlSocket int
 	var err error
diff --git a/pkg/init/cmd/service/runc.go b/pkg/init/cmd/service/runc.go
index 656912bfd..30e85c38d 100644
--- a/pkg/init/cmd/service/runc.go
+++ b/pkg/init/cmd/service/runc.go
@@ -160,11 +160,7 @@ func runcInit(rootPath, serviceType string) int {
 	_ = 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)
-	}
+	logger.Symlink(varLogLink)
 
 	return status
 }