Plugins

Let’s have a look at plugins. Each of the six steps defined by Plans supports multiple methods. These methods are implemented by plugins which are dynamically loaded from the standard location under tmt/steps and from all directories provided in the TMT_PLUGINS environment variable.

Inheritance

The plugin is implemented by a class which inherits from the corresponding step class, for example ProvisionPodman inherits from the ProvisionPlugin class. See the Classes page for more details about the class structure. The plugin class defines a couple of essential methods:

options()
command line options specific for given plugin
wake()
additional plugin data processing after the wake-up
show()
give a concise overview of the step configuration
go()
the main implementation of the plugin functionality

There may be additional required methods which need to be implemented. See individual plugin examples for details.

Examples

Example plugin skeletons are located in the examples/plugins directory. Get some inspiration for writing plugins there. There is a lot of comments and you can use the examples as a skeleton for your new plugin.

The discover plugin example demonstrates a simple plugin functionality defining an additional tests() method which returns a list of discovered tests.

The provision step example is more complex and consists of two classes. In addition to the provisioning part itself it also implements the GuestExample class which inherits from Guest and overloads its methods to handle special guest features which cannot be covered by generic ssh implementation of the Guest class.