Extending pytest-mh for Your Needs

pytest-mh uses a yaml-formatted configuration file that contains the list of multihost domains, hosts and their roles that are required for the tests. These configuration entities are converted into their Python representations that can and should be extended to provide additional configuration and high level API for your project as well as the setup and teardown code.

Note

Do not confuse domains with DNS domains. The domains in the configuration file do not have to follow any DNS patterns. Their purpose is to identify a group of hosts.

As a general rule, hosts within the same domain that have the same role should be interchangeable – it should not matter to which of the host you talk, you always should get the same result, for example a database replicas or servers behind a load balancer.

The following snippet shows a minimal configuration file with one domain and one host.

Minimal configuration file

domains:
- id: example
  hosts:
  - hostname: client.test
    role: client

The file is parsed into:

MultihostConfig: top level object, container for the whole configuration
MultihostDomain: the domain object, container for all hosts within a domain, one for each domain. From the previous example this would be example
MultihostHost: individual hosts, one for each host. From the previous example the name would be client

Additionally, each host has a role assigned. This role creates a MultihostRole object, this object has a short lifespan and it exists only for a duration of one test. A new role object is created for each test. Further, MultihostUtility classes can be used to share code and functionality between roles and hosts.

Each test is assigned with a topology. A topology describes what domains and roles are required to run the test. If the current configuration does not satisfy this requirement, the test is silently skipped.

Read the following articles to get more information on how to define topologies and use and extend these classes.