lcow: fix debug in startServiceVMIfNotRunning()

When go-1.11beta1 is used for building, the following error is
reported:

> 14:56:20 daemon\graphdriver\lcow\lcow.go:236: Debugf format %s reads
> arg #2, but call has 1 arg

While fixing this, let's also fix a few other things in this
very function (startServiceVMIfNotRunning):

1. Do not use fmt.Printf when not required.
2. Use `title` whenever possible.
3. Don't add `id` to messages as `title` already has it.
4. Remove duplicated colons.
5. Try to unify style of messages.
6. s/startservicevmifnotrunning/startServiceVMIfNotRunning/
...

In general, logging/debugging here is a mess and requires much more
love than I can give it at the moment. Areas for improvement:

1. Add a global var logger = logrus.WithField("storage-driver", "lcow")
and use it everywhere else in the code.
2. Use logger.WithField("id", id) whenever possible (same for "context"
and other similar fields).
3. Revise all the errors returned to be uniform.
4. Make use of errors.Wrap[f] whenever possible.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

daemon/graphdriver/lcow/lcow.go

@@ -219,21 +219,21 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 	// Use the global ID if in global mode
 	id = d.getVMID(id)
 
-	title := fmt.Sprintf("lcowdriver: startservicevmifnotrunning %s:", id)
+	title := "lcowdriver: startServiceVMIfNotRunning " + id
 
 	// Attempt to add ID to the service vm map
-	logrus.Debugf("%s: Adding entry to service vm map", title)
+	logrus.Debugf("%s: adding entry to service vm map", title)
 	svm, exists, err := d.serviceVms.add(id)
 	if err != nil && err == errVMisTerminating {
 		// VM is in the process of terminating. Wait until it's done and and then try again
-		logrus.Debugf("%s: VM with current ID still in the process of terminating: %s", title, id)
+		logrus.Debugf("%s: VM with current ID still in the process of terminating", title)
 		if err := svm.getStopError(); err != nil {
-			logrus.Debugf("%s: VM %s did not stop successfully: %s", title, id, err)
+			logrus.Debugf("%s: VM did not stop successfully: %s", title, err)
 			return nil, err
 		}
 		return d.startServiceVMIfNotRunning(id, mvdToAdd, context)
 	} else if err != nil {
-		logrus.Debugf("%s: failed to add service vm to map: %s", err)
+		logrus.Debugf("%s: failed to add service vm to map: %s", title, err)
 		return nil, fmt.Errorf("%s: failed to add to service vm map: %s", title, err)
 	}
 
@@ -248,7 +248,7 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 	}
 
 	// We are the first service for this id, so we need to start it
-	logrus.Debugf("%s: service vm doesn't exist. Now starting it up: %s", title, id)
+	logrus.Debugf("%s: service vm doesn't exist. Now starting it up", title)
 
 	defer func() {
 		// Signal that start has finished, passing in the error if any.
@@ -261,7 +261,7 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 
 	// Generate a default configuration
 	if err := svm.config.GenerateDefault(d.options); err != nil {
-		return nil, fmt.Errorf("%s failed to generate default gogcs configuration for global svm (%s): %s", title, context, err)
+		return nil, fmt.Errorf("%s: failed to generate default gogcs configuration for global svm (%s): %s", title, context, err)
 	}
 
 	// For the name, we deliberately suffix if safe-mode to ensure that it doesn't
@@ -277,19 +277,19 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 	// and not in the process of being created by another thread.
 	scratchTargetFile := filepath.Join(d.dataRoot, scratchDirectory, fmt.Sprintf("%s.vhdx", id))
 
-	logrus.Debugf("%s locking cachedScratchMutex", title)
+	logrus.Debugf("%s: locking cachedScratchMutex", title)
 	d.cachedScratchMutex.Lock()
 	if _, err := os.Stat(d.cachedScratchFile); err == nil {
 		// Make a copy of cached scratch to the scratch directory
-		logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) cloning cached scratch for mvd", context)
+		logrus.Debugf("%s: (%s) cloning cached scratch for mvd", title, context)
 		if err := client.CopyFile(d.cachedScratchFile, scratchTargetFile, true); err != nil {
-			logrus.Debugf("%s releasing cachedScratchMutex on err: %s", title, err)
+			logrus.Debugf("%s: releasing cachedScratchMutex on err: %s", title, err)
 			d.cachedScratchMutex.Unlock()
 			return nil, err
 		}
 
 		// Add the cached clone as a mapped virtual disk
-		logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) adding cloned scratch as mvd", context)
+		logrus.Debugf("%s: (%s) adding cloned scratch as mvd", title, context)
 		mvd := hcsshim.MappedVirtualDisk{
 			HostPath:          scratchTargetFile,
 			ContainerPath:     toolsScratchPath,
@@ -299,7 +299,7 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 		svm.scratchAttached = true
 	}
 
-	logrus.Debugf("%s releasing cachedScratchMutex", title)
+	logrus.Debugf("%s: releasing cachedScratchMutex", title)
 	d.cachedScratchMutex.Unlock()
 
 	// If requested to start it with a mapped virtual disk, add it now.
@@ -309,39 +309,39 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 	}
 
 	// Start it.
-	logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) starting %s", context, svm.config.Name)
+	logrus.Debugf("%s: (%s) starting %s", title, context, svm.config.Name)
 	if err := svm.config.StartUtilityVM(); err != nil {
 		return nil, fmt.Errorf("failed to start service utility VM (%s): %s", context, err)
 	}
 
 	// defer function to terminate the VM if the next steps fail
 	defer func() {
 		if err != nil {
-			waitTerminate(svm, fmt.Sprintf("startServiceVmIfNotRunning: %s (%s)", id, context))
+			waitTerminate(svm, fmt.Sprintf("%s: (%s)", title, context))
 		}
 	}()
 
 	// Now we have a running service VM, we can create the cached scratch file if it doesn't exist.
-	logrus.Debugf("%s locking cachedScratchMutex", title)
+	logrus.Debugf("%s: locking cachedScratchMutex", title)
 	d.cachedScratchMutex.Lock()
 	if _, err := os.Stat(d.cachedScratchFile); err != nil {
-		logrus.Debugf("%s (%s): creating an SVM scratch", title, context)
+		logrus.Debugf("%s: (%s) creating an SVM scratch", title, context)
 
 		// Don't use svm.CreateExt4Vhdx since that only works when the service vm is setup,
 		// but we're still in that process right now.
 		if err := svm.config.CreateExt4Vhdx(scratchTargetFile, client.DefaultVhdxSizeGB, d.cachedScratchFile); err != nil {
-			logrus.Debugf("%s (%s): releasing cachedScratchMutex on error path", title, context)
+			logrus.Debugf("%s: (%s) releasing cachedScratchMutex on error path", title, context)
 			d.cachedScratchMutex.Unlock()
 			logrus.Debugf("%s: failed to create vm scratch %s: %s", title, scratchTargetFile, err)
 			return nil, fmt.Errorf("failed to create SVM scratch VHDX (%s): %s", context, err)
 		}
 	}
-	logrus.Debugf("%s (%s): releasing cachedScratchMutex", title, context)
+	logrus.Debugf("%s: (%s) releasing cachedScratchMutex", title, context)
 	d.cachedScratchMutex.Unlock()
 
 	// Hot-add the scratch-space if not already attached
 	if !svm.scratchAttached {
-		logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) hot-adding scratch %s", context, scratchTargetFile)
+		logrus.Debugf("%s: (%s) hot-adding scratch %s", title, context, scratchTargetFile)
 		if err := svm.hotAddVHDsAtStart(hcsshim.MappedVirtualDisk{
 			HostPath:          scratchTargetFile,
 			ContainerPath:     toolsScratchPath,
@@ -353,7 +353,7 @@ func (d *Driver) startServiceVMIfNotRunning(id string, mvdToAdd []hcsshim.Mapped
 		svm.scratchAttached = true
 	}
 
-	logrus.Debugf("lcowdriver: startServiceVmIfNotRunning: (%s) success", context)
+	logrus.Debugf("%s: (%s) success", title, context)
 	return svm, nil
 }