[Filebeat] fails to enroll to centralized management in OS Windows

[yuri-tceretian]

• Product: Filebeat
• Version: 7.2.0
• Operating System: Windows 2008 R2

Description of the bug

Enrolling to centralized management fails while creating a backup of the current configuration. Error message:

Error while enrolling: creating a backup copy of current settings: rename filebeat.yml filebeat.yml.2019-07-05T06:01:52-04:00.bak: The filename, directory name, or volume label syntax is incorrect.

The error is generated by this code (thanks to @adriansr for pointing)

beats/x-pack/libbeat/management/enroll.go

Lines 58 to 64 in 4cc4eee

	// backup current settings:
	backConfigFile := configFile + "." + ts.Format(time.RFC3339) + ".bak"
	fmt.Println("Saving a copy of current settings to " + backConfigFile)
	err = file.SafeFileRotate(backConfigFile, configFile)
	if err != nil {
	return errors.Wrap(err, "creating a backup copy of current settings")
	}

The name of the backup file is not valid in the Windows ecosystem.

Steps to reproduce

• Install filebeat using the official documentation
• Set up Elasticsearch and Kibana
• Get enrollment token in kibana
• Run filebeat.exe with the command enroll