pytest-multihost 0.3

Utility for writing multi-host tests for pytest

A pytest plugin for multi-host testing.

Downloading

Release tarballs will be made available for download from Fedora Hosted:

https://fedorahosted.org/released/python-pytest-multihost/

The goal is to include this project in Fedora repositories. Until that happens, you can use testing builds from COPR – see “Developer links” below.

You can also install using pip:

https://pypi.python.org/pypi/pytest-multihost

Usage

This plugin takes a description of your infrastructure, and provides, via a fixture, Host objects that commands can be called on.

It is intended as a general base for a framework; any project using it will need to extend it for its own needs.

The object provided to tests is a Config object, which has (among others) these attributes:

test_dir – directory to store test-specific data in,
           defaults to /root/multihost_tests
ipv6 – true if connecting via IPv6

domains – the list of domains

Hosts to run on are arranged in domains, which have:

name – the DNS name of the domain
type – a string specifying the type of the domain ('default' by default)

config – the Config this domain is part of
hosts – list of hosts in this domain

And the hosts have:

role – type of this host; should encode the OS and installed packages
hostname – fully qualified hostname, usually reachable from other hosts
shortname – first component of hostname
external_hostname – hostname used to connect to this host
ip – IP address

domain – the Domain this host is part of

transport – allows operations like uploading and downloading files
run_command() – runs the given command on the host

For each object – Config, Domain, Host – one can provide subclasses to modify the behavior (for example, FreeIPA would add Host methods to run a LDAP query or to install an IPA server). Each object has from_dict and to_dict methods, which can add additional attributes – for example, Config.ntp_server.

To use the multihost plugin in tests, create a fixture listing the domains and what number of which host role is needed:

import pytest
from pytest_multihost import make_multihost_fixture

@pytest.fixture(scope='class')
def multihost(request):
    mh = make_multihost_fixture(
        request,
        descriptions=[
            {
                'type': 'ipa',
                'hosts': {
                    'master': 1,
                    'replica': 2,
                },
            },
        ],
    )
    return mh.install()

If not enough hosts are available, all tests that use the fixture are skipped.

The object returned from make_multihost_fixture only has the “config” attribute (and the install method). Users are expected to add convenience attributes. For example, FreeIPA, which typically uses a single domain with one master, several replicas and some clients, would do:

from pytest_multihost import make_multihost_fixture

def multihost(request):
    mh = make_multihost_fixture(...)
    mh.domain = mh.config.domains[0]
    [mh.master] = mh.domain.hosts_by_role('master')
    mh.replicas = mh.domain.hosts_by_role('replica')
    mh.clients = mh.domain.hosts_by_role('client')
    return mh.install()

As with any pytest fixture, this can be used by getting it as a function argument. Unlike regular pytest fixtures, it needs to be used on a class: its install() method calls the class’ install(), and at cleanup time, uninstall() is called. For a simplified example, FreeIPA usage could look something like this:

class TestMultihost(object):
    def install(self, multihost):
        multihost.master.run_command(['ipa-server-install'])

    def uninstall(self, multihost):
        multihost.master.run_command(['ipa-server-install', '--uninstall'])

    def test_installed(self, multihost):
        multihost.master.run_command(['ipa', 'ping'])

Note

install() and uninstall() are not testing functions, they are only called with (self, multihost).

The description of infrastructure is provided in a JSON or YAML file, which is named on the py.test command line. For example:

ssh_key_filename: ~/.ssh/id_rsa
domains:
  - name: adomain.test
    hosts:
      - name: master
        ip: 192.0.2.1
        role: master
      - name: replica1
        ip: 192.0.2.2
        role: replica
      - name: replica2
        ip: 192.0.2.3
        role: replica
        external_hostname: r2.adomain.test
      - name: client1
        ip: 192.0.2.4
        role: client
      - name: extra
        ip: 192.0.2.6
        role: extrarole
  - name: bdomain.test
    hosts:
      - name: master.bdomain.test
        ip='192.0.2.65
        role: master

$ py.test –multihost-config=/path/to/configfile.yaml

To use YAML files, the PyYAML package is required. Without it only JSON files can be used.

Contributing

The project is happy to accept patches! Please format your contribution using the FreeIPA patch guidelines, and send it to <[e-mail]>. Any development discussion is welcome there.

Someday the project might get its own list, but that seems premature now.

Developer links

• Bug tracker: https://fedorahosted.org/python-pytest-multihost/report/3

• Code browser: ​https://git.fedorahosted.org/cgit/python-pytest-multihost

• git clone ​https://git.fedorahosted.org/git/python-pytest-multihost.git

• Unstable packages for Fedora: https://copr.fedoraproject.org/coprs/pviktori/pytest-plugins/

To release, update version in setup.py, add a Git tag like “v0.3”, and run make tarball. Running make upload will put the tarball to Fedora Hosted and PyPI, and a SRPM on Fedorapeople, if you have the rights. Running make release will upload and fire a COPR build.