Merge pull request #2 from Azure/dev/vivekl/fixGetSequenceNumber

Fix Get sequence number from config folder

main/cmds.go

@@ -73,49 +73,11 @@ func install(ctx *log.Context, h HandlerEnvironment, report *RunCommandInstanceV
 		return "", "", errors.Wrap(err, "failed to create data dir")
 	}
 
-	// If the file mrseq does not exists
-	//  the extension has never been installed on this VMs before
-	// if _, err := os.Stat(mostRecentSequence); os.IsNotExist(err) {
-	// 	migrateToMostRecentSequence(ctx, h, seqNum)
-	// }
-
 	ctx.Log("event", "created data dir", "path", dataDir)
 	ctx.Log("event", "installed")
 	return "", "", nil
 }
 
-func migrateToMostRecentSequence(ctx *log.Context, h HandlerEnvironment, seqNum int) {
-	// The status folder is used instead of the settings because the settings file is written
-	// by the agent before install is called.  As a result, the extension cannot determine if this
-	// is a new install or an upgrade.
-	//
-	// If this is an upgrade there will be a status file. The agent will re-write the last status
-	// file to indicate that the upgrade happened successfully. The extension uses the last status
-	// sequence number to determine the last settings file that was executed.
-	//
-	// The agent helpfully copies mrseq every time an extension is upgraded thereby preserving the
-	// most recent executed sequence. If extensions use mrseq they benefit from this mechanism, and
-	// do not have invent another method.  The CustomScript extension should have been using this
-	// from the beginning, but it was not.
-	//
-	computedSeqNum, err := FindSeqNumStatus(h.HandlerEnvironment.StatusFolder)
-	if err != nil {
-		// If there was an error, the sequence number is zero.
-		ctx.Log("event", "migrate to mrseq", "error", err)
-		return
-	}
-
-	fout, err := os.Create(mostRecentSequence)
-	if err != nil {
-		ctx.Log("event", "migrate to mrseq", "error", err)
-		return
-	}
-	defer fout.Close()
-
-	ctx.Log("event", "migrate to mrseq", "message", fmt.Sprintf("migrated mrseq to %v", computedSeqNum))
-	fout.WriteString(fmt.Sprintf("%v", computedSeqNum))
-}
-
 func uninstall(ctx *log.Context, h HandlerEnvironment, report *RunCommandInstanceView, extName string, seqNum int) (string, string, error) {
 	{ // a new context scope with path
 		ctx = ctx.With("path", dataDir)

main/handlersettingscommon.go

@@ -23,16 +23,6 @@ type handlerSettingsCommon struct {
 	SettingsCertThumbprint  string                 `json:"protectedSettingsCertThumbprint"`
 }
 
-// settingsPath returns the full path to the .settings file with the
-// highest sequence number found in configFolder.
-func settingsPath(configFolder string) (string, error) {
-	seq, err := FindSeqNumConfig(configFolder)
-	if err != nil {
-		return "", fmt.Errorf("Cannot find seqnum: %v", err)
-	}
-	return filepath.Join(configFolder, fmt.Sprintf("%d%s", seq, ".settings")), nil
-}
-
 // ReadSettings locates the .settings file and returns public settings
 // JSON, and protected settings JSON (by decrypting it with the keys in
 // configFolder).

main/main.go

@@ -37,6 +37,8 @@ var (
 
 	// configExtensionName environment variable should be set by VMAgent to extension name
 	configExtensionName = "ConfigExtensionName"
+
+	configFileExtension = ".settings"
 )
 
 func main() {
@@ -64,23 +66,26 @@ func main() {
 			os.Exit(cmd.failExitCode)
 		}
 	}
+
+	extensionName := os.Getenv(configExtensionName)
+	if extensionName != "" {
+		ctx = ctx.With("extensionName", extensionName)
+		downloadDir = downloadDir + "/" + extensionName
+		mostRecentSequence = extensionName + "." + mostRecentSequence
+		pidFilePath = extensionName + "." + pidFilePath
+	}
+
 	// Read the seqNum from latest config file in case VMAgent did not set it as env variable
 	if seqNum == -1 {
-		seqNum, err = FindSeqNumConfig(hEnv.HandlerEnvironment.ConfigFolder)
+		seqNum, err = FindSequenceNumberFromConfig(hEnv.HandlerEnvironment.ConfigFolder, configFileExtension, extensionName)
 		if err != nil {
-			ctx.Log("messsage", "failed to find sequence number", "error", err)
+			ctx.Log("FindSequenceNumberFromConfig", "failed to find sequence number from config folder.", "error", err)
+		} else {
+			ctx.Log("FindSequenceNumberFromConfig", fmt.Sprintf("Sequence number determined from config folder: %d", seqNum))
 		}
 	}
 	ctx = ctx.With("seq", seqNum)
 
-	extName := os.Getenv(configExtensionName)
-	if extName != "" {
-		ctx = ctx.With("extensionName", extName)
-		downloadDir = downloadDir + "/" + extName
-		mostRecentSequence = extName + "." + mostRecentSequence
-		pidFilePath = extName + "." + pidFilePath
-	}
-
 	// check sub-command preconditions, if any, before executing
 	ctx.Log("event", "start")
 	if cmd.pre != nil {
@@ -100,15 +105,15 @@ func main() {
 		EndTime:          "",
 	}
 
-	reportInstanceView(ctx, hEnv, extName, seqNum, StatusTransitioning, cmd, &instanceView)
+	reportInstanceView(ctx, hEnv, extensionName, seqNum, StatusTransitioning, cmd, &instanceView)
 
 	// execute the subcommand
-	stdout, stderr, err := cmd.invoke(ctx, hEnv, &instanceView, extName, seqNum)
+	stdout, stderr, err := cmd.invoke(ctx, hEnv, &instanceView, extensionName, seqNum)
 	if err != nil {
 		ctx.Log("event", "failed to handle", "error", err)
 		instanceView.ExecutionMessage = "Execution failed: " + err.Error()
 		instanceView.EndTime = time.Now().UTC().Format(time.RFC3339)
-		reportInstanceView(ctx, hEnv, extName, seqNum, StatusSuccess, cmd, &instanceView)
+		reportInstanceView(ctx, hEnv, extensionName, seqNum, StatusSuccess, cmd, &instanceView)
 		os.Exit(cmd.failExitCode)
 	}
 	instanceView.ExecutionMessage = "Execution completed"
@@ -116,7 +121,7 @@ func main() {
 	instanceView.Output = stdout
 	instanceView.Error = stderr
 	instanceView.EndTime = time.Now().UTC().Format(time.RFC3339)
-	reportInstanceView(ctx, hEnv, extName, seqNum, StatusSuccess, cmd, &instanceView)
+	reportInstanceView(ctx, hEnv, extensionName, seqNum, StatusSuccess, cmd, &instanceView)
 	ctx.Log("event", "end")
 }
 

main/seqnum.go

@@ -17,29 +17,22 @@ const (
 	chmod = os.FileMode(0600)
 )
 
-// FindSeqNumConfig gets the laster seq no from config files
-func FindSeqNumConfig(path string) (int, error) {
-	return FindSeqNum(path, ".settings")
-}
-
-// FindSeqNumStatus gets the laster seq no from status files
-func FindSeqNumStatus(path string) (int, error) {
-	return FindSeqNum(path, ".status")
-}
-
-// FindSeqNum finds the file with the highest number under configFolder
-// named like 0.settings, 1.settings so on.
-func FindSeqNum(path, ext string) (int, error) {
-	g, err := filepath.Glob(filepath.Join(path, fmt.Sprintf("*%s", ext)))
+// FindSequenceNumberFromConfig finds the file with the highest sequence number for an extension under configFolder
+// named like <RunCommandName>.0.settings, <RunCommandName>.1.settings so on.
+func FindSequenceNumberFromConfig(path, fileExtension string, extensionName string) (int, error) {
+	g, err := filepath.Glob(filepath.Join(path, fmt.Sprintf("%s.*%s", extensionName, fileExtension)))
 	if err != nil {
 		return 0, err
 	}
 	seqs := make([]int, len(g))
 	for _, v := range g {
 		f := filepath.Base(v)
-		i, err := strconv.Atoi(strings.TrimSuffix(f, filepath.Ext(f)))
+		fileNameWithoutExtension := strings.TrimSuffix(f, filepath.Ext(f))
+		dotAndSequenceNumberString := filepath.Ext(fileNameWithoutExtension) // returns something like ".<sequenceNumber>"
+		sequenceNumberString := dotAndSequenceNumberString[1:]               // Remove '.' in the front
+		i, err := strconv.Atoi(sequenceNumberString)
 		if err != nil {
-			return 0, fmt.Errorf("Can't parse int from filename: %s", f)
+			continue // continue to the next filename if Atoi fails
 		}
 		seqs = append(seqs, i)
 	}