NIFI-3696 - Initial commit of ConfigMigration and FileManager tools

[YolandaMDavis]

Usage information for this tool is below and is also included in the PR here:
https://github.com/YolandaMDavis/nifi/blob/f347869ceefd65d570fa5f9ab6d8daa6db2f4b57/nifi-docs/src/main/asciidoc/administration-guide.adoc

File Manager

The File Manager utility allows system administrators to take a backup of an existing NiFi installation, install a new version of NiFi
in a designated location (while migrating any previous configuration settings) or restore an installation from a previous backup.
File Manager supports NiFi version 1.0.0 and higher and is available in 'file-manager.bat' file for use on Windows machines.

To show help:

file-manager.sh -h

The following are available options:

• -o,--operation <arg> File operation (install | backup | restore)
• -b,--backupDir <arg> Backup NiFi Directory (used with backup or restore operation)
• -c,--nifiCurrentDir <arg> Current NiFi Installation Directory (used optionally with install or restore operation)
• -d,--nifiInstallDir <arg> NiFi Installation Directory (used with install or restore operation)
• -i,--installFile <arg> NiFi Install File (used with install operation)
• -r,--nifiRollbackDir <arg> NiFi Installation Directory (used with install or restore operation)
• -t,--bootstrapConf <arg> Current NiFi Bootstrap Configuration File (used optionally)
• -m,--moveRepositories Allow repositories to be moved to new/restored nifi directory from existing installation, if available (used optionally with install or restore operation)
• -x,--overwriteConfigs Overwrite existing configuration directory with upgrade changes (used optionally with install or restore operation)
• -v,--verbose Verbose messaging (optional)
• -h,--help Print help info (optional)

Example usage on Linux:

 ./file-manager.sh
 -o backup
 –b /tmp/nifi_bak
 –c /usr/nifi_old
 -v

• backup NiFi installation
• option -t may be provided to ensure backup of external boostrap.conf file

./file-manager.sh
 -o install
 –i nifi-1.3.0.tar.gz
 –d /usr/nifi
 –c /usr/nifi/nifi_old
 -t /usr/nifi/old_conf/bootstrap.conf
 -v
 -m

• install NiFi using compressed tar file into /usr/nifi directory (should install as /usr/nifi/nifi-1.3.0).
• migrate existing configurations with location determined by external bootstrap.conf and move over repositories from nifi_old
• options -t and -c should both be provided if migration of configurations, state and repositories are required

 ./file-manager.sh
 -o restore
 –b /tmp/nifi_bak
 –r /usr/nifi_old
 –c /usr/nifi
 -m
 -v

• restore NiFi installation from backup directory and move back repositories
• option -t may be provided to ensure bootstrap.conf is restored to the file path provided, otherwise it is placed in the
• default directory under the rollback path (e.g. /usr/nifi_old/conf)

Expected Behavior

Backup:

During the backup operation a backup directory is created in a designated location for an existing NiFi installation. Backups will capture all critical files
(including any internal or external configurations, libraries, scripts and documents) however it excludes backing up repositories and logs due to potential size.
If configuration/library files are external from the existing installation folder the backup operation will capture those as well.

Install:

During the install operation File Manager will perform installation using the designated NiFi binary file (either tar.gz or zip file)
to create a new installation or migrate an existing nifi installation to a new one. Installation can optionally move repositories (if located within the configuration
folder of the current installation) to the new installation as well as migrate configuration files to the newer installation.

Restore:

The restore operation allows an existing installation to revert back to a previous installation. Using an existing backup directory (created from the backup operation)
the FileManager utility will restore libraries, scripts and documents as well as revert to previous configurations.

Thank you for submitting a contribution to Apache NiFi.

In order to streamline the review of the contribution we ask you
to ensure the following steps have been taken:

For all changes:

• Is there a JIRA ticket associated with this PR? Is it referenced
  in the commit message?

• Does your PR title start with NIFI-XXXX where XXXX is the JIRA number you are trying to resolve? Pay particular attention to the hyphen "-" character.

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Note:

Please ensure that once the PR is submitted, you check travis-ci for build issues and submit an update to your PR as soon as possible.

[brosander]

We should notify the user that if they upgrade with -m to also move repositories, start nifi, then try to downgrade, it's likely that the older implementation will not be able to read the newer repos.

[YolandaMDavis]

@brosander agreed will update the admin guide and will also add verbose information during install execution.

[brosander]

+1 on condition that we document limitations of downgrade with respect to repos

[YolandaMDavis]

@brosander I've added updates to documentation as well as additional verbose information as recommended. please let me know if you see any additional issues