velero/docs/plugins.md

Plugins

Velero has a plugin architecture that allows users to add their own custom functionality to Velero backups & restores without having to modify/recompile the core Velero binary. To add custom functionality, users simply create their own binary containing implementations of Velero's plugin kinds (described below), plus a small amount of boilerplate code to expose the plugin implementations to Velero. This binary is added to a container image that serves as an init container for the Velero server pod and copies the binary into a shared emptyDir volume for the Velero server to access.

Multiple plugins, of any type, can be implemented in this binary.

A fully-functional sample plugin repository is provided to serve as a convenient starting point for plugin authors.

Plugin Naming

When naming your plugin, keep in mind that the name needs to conform to these rules:

• have two parts separated by '/'
• none of the above parts can be empty
• the prefix is a valid DNS subdomain name
• a plugin with the same name cannot not already exist

Some examples:

- example.io/azure
- 1.2.3.4/5678
- example-with-dash.io/azure

You will need to give your plugin(s) a name when registering them by calling the appropriate RegisterX function: https://github.com/heptio/velero/blob/0e0f357cef7cf15d4c1d291d3caafff2eeb69c1e/pkg/plugin/framework/server.go#L42-L60

Plugin Kinds

Velero currently supports the following kinds of plugins:

• Object Store - persists and retrieves backups, backup logs and restore logs
• Volume Snapshotter - creates volume snapshots (during backup) and restores volumes from snapshots (during restore)
• Backup Item Action - executes arbitrary logic for individual items prior to storing them in a backup file
• Restore Item Action - executes arbitrary logic for individual items prior to restoring them into a cluster

Plugin Logging

Velero provides a logger that can be used by plugins to log structured information to the main Velero server log or per-backup/restore logs. It also passes a --log-level flag to each plugin binary, whose value is the value of the same flag from the main Velero process. This means that if you turn on debug logging for the Velero server via --log-level=debug, plugins will also emit debug-level logs. See the sample repository for an example of how to use the logger within your plugin.