Configuration Management on

Overview

Mon, 17 Feb 2025 00:00:00 +0000

OpenNebula has tens of configuration files, where cloud administrators can fine-tune the behavior of their cloud environment. When carrying out an upgrade to a newer minor OpenNebula version (X.Y), unfortunately all custom changes in configuration files must be migrated to new configuration files. OpenNebula includes a dedicated tool (onecfg) which automates and simplifies the upgrade of configuration files.

This Chapter describes how to use the configuration management tool to:

Basic Usage

Mon, 17 Feb 2025 00:00:00 +0000

This section covers onecfg tool subcommands:

status - Version status
init - Initialize version management state
validate - Validate current configuration files
diff - Identify changes in configuration files
patch - Apply ad-hoc changes (from diff) in configuration files
upgrade - Upgrade configuration files to a new version

Important

This command must be always run under privileged user root directly or via sudo. For example:

Diff Formats

Mon, 17 Feb 2025 00:00:00 +0000

The configuration management tool onecfg allows us to compare the configuration files to identify user changes against the OpenNebula distributed files. The result of a comparison, the differential output, describes all the individual changes which were made and which can even be applied again later or on a different machine.

The following table shows supported formats by each subcommand:

Format	Description	`onecfg diff`	`onecfg patch`
`text`	Easy human-readable text	YES (default)	NO
`line`	Single line for one change	YES	YES (default)
`yaml`	Complete change structure	YES	YES

Only line format will be described here in detail, as it’s powerful in achieving even complex changes and easy enough to read or write manually.

Troubleshooting

Mon, 17 Feb 2025 00:00:00 +0000

The configuration files upgrade is a complex process during which many problems may arise. The root cause of all problems are users’ customizations made in the configuration files in places that also change in a newer version. Because the upgrade process tries to apply changes from newer versions to existing files, the tool can be confused when it reaches the incompatibly modified part.

In case of a problem, the upgrade process terminates and leaves the state of configuration files unchanged. There is no automatic mechanism preconfigured, but the user has to instruct the tool on how to resolve the problem. This is done by specifying patch modes globally for the whole process, for a particular file, or for a particular file and (intermediate) version the user is upgrading to.

Appendix - List of Configurations

Mon, 17 Feb 2025 00:00:00 +0000

The following table describes all configuration files and their type from the following directories:

/etc/one/
/var/lib/one/remotes/

These files can be managed using the onecfg tool, refer to the onecfg documentation for more details: