pytest-ansible

This repository contains a plugin for py.test which adds several fixtures for running ansible modules, or inspecting ansible_facts. While one can simply call out to ansible using the subprocess module, having to parse stdout to determine the outcome of the operation is unpleasant and prone to error. With pytest-ansible, modules return JSON data which you can inspect and act on, much like with an ansible playbook.

Installation

Install this plugin using pip

pip install pytest-ansible

Usage

Once installed, the following py.test command-line parameters are available:

py.test \
    [--inventory <path_to_inventory>] \
    [--host-pattern <host-pattern>] \
    [--connection <plugin>] \
    [--module-path <path_to_modules] \
    [--user <username>] \
    [--become] \
    [--become-user <username>] \
    [--become-method <method>] \
    [--limit <limit>] \
    [--check]

Inventory

Using ansible first starts with defining your inventory. This can be done several ways, but to start, we'll use the ansible_adhoc fixture.

def test_my_inventory(ansible_adhoc):
    hosts = ansible_adhoc()

In the example above, the hosts variable is an instance of the HostManager class and describes your ansible inventory. For this to work, you'll need to tell ansible where to find your inventory. Inventory can be anything supported by ansible, which includes an INI file or an executable script that returns properly formatted JSON. For example,

py.test --inventory my_inventory.ini --host-pattern all

or

py.test --inventory path/to/my/script.py --host-pattern webservers

or

py.test --inventory one.example.com,two.example.com --host-pattern all

In the above examples, the inventory provided at runtime will be used in all tests that use the ansible_adhoc fixture. A more realistic scenario may involve using different inventory files (or host patterns) with different tests. To accomplish this, the fixture ansible_adhoc allows you to customize the inventory parameters. Read on for more detail on using the ansible_adhoc fixture.

Fixture ansible_adhoc

The ansible_adhoc fixture returns a function used to initialize a HostManager object. The ansible_adhoc fixture will default to parameters supplied to the py.test command-line, but also allows one to provide keyword arguments used to initialize the inventory.

The example below demonstrates basic usage with options supplied at run-time to py.test.

def test_all_the_pings(ansible_adhoc):
    ansible_adhoc().all.ping()

The following example demonstrates available keyword arguments when creating a HostManager object.

def test_uptime(ansible_adhoc):
    # take down the database
    ansible_adhoc(inventory='db1.example.com,', user='ec2-user', 
        become=True, become_user='root').all.command('reboot')

The HostManager object returned by the ansible_adhoc() function provides numerous ways of calling ansible modules against some, or all, of the inventory. The following demonstates sample usage.

def test_host_manager(ansible_adhoc):
    hosts = ansible_adhoc()

    # __getitem__
    hosts['all'].ping()
    hosts['localhost'].ping()

    # __getattr__
    hosts.all.ping()
    hosts.localhost.ping()

    # Supports [ansible host patterns](http://docs.ansible.com/ansible/latest/intro_patterns.html)
    hosts['webservers:!phoenix'].ping()  # all webservers that are not in phoenix
    hosts[0].ping()
    hosts[0:2].ping()

    assert 'one.example.com' in hosts

    assert hasattr(hosts, 'two.example.com')

    for a_host in hosts:
        a_host.ping()

Fixture localhost

The localhost fixture is a convenience fixture that surfaces a ModuleDispatcher instance for ansible host running pytest. This is convenient when using ansible modules that typically run on the local machine, such as cloud modules (ec2, gce etc...).

def test_do_something_cloudy(localhost, ansible_adhoc):
    """Deploy an ec2 instance using multiple fixtures."""
    params = dict(
        key_name='somekey',
        instance_type='t2.micro',
        image='ami-123456',
        wait=True,
        group='webserver',
        count=1,
        vpc_subnet_id='subnet-29e63245',
        assign_public_ip=True,
    )

    # Deploy an ec2 instance from localhost using the `ansible_adhoc` fixture
    ansible_adhoc(inventory='localhost,', connection='local').localhost.ec2(**params)

    # Deploy an ec2 instance from localhost using the `localhost` fixture
    localhost.ec2(**params)

Fixture ansible_module

The ansible_module fixture allows tests and fixtures to call ansible modules. Unlike the ansible_adhoc fixture, this fixture only uses the options supplied to py.test at run time.

A very basic example demonstrating the ansible ping module:

def test_ping(ansible_module):
    ansible_module.ping()

A more involved example of updating the sshd configuration, and restarting the service.

def test_sshd_config(ansible_module):

    # update sshd MaxSessions
    contacted = ansible_module.lineinfile(
        dest="/etc/ssh/sshd_config",
        regexp="^#?MaxSessions .*",
        line="MaxSessions 150")
    )

    # assert desired outcome
    for (host, result) in contacted.items():
        assert 'failed' not in result, result['msg']
        assert 'changed' in result

    # restart sshd
    contacted = ansible_module.service(
        name="sshd",
        state="restarted"
    )

    # assert successful restart
    for (host, result) in contacted.items():
        assert 'changed' in result and result['changed']
        assert result['name'] == 'sshd'

    # do other stuff ...

Fixture ansible_facts

The ansible_facts fixture returns a JSON structure representing the system facts for the associated inventory. Sample fact data is available in the ansible documentation.

Note, this fixture is provided for convenience and could easily be called using ansible_module.setup().

A systems facts can be useful when deciding whether to skip a test ...

def test_something_with_amazon_ec2(ansible_facts):
    for facts in ansible_facts:
        if 'ec2.internal' != facts['ansible_domain']:
            pytest.skip("This test only applies to ec2 instances")

Additionally, since facts are just ansible modules, you could inspect the contents of the ec2_facts module for greater granularity ...

def test_terminate_us_east_1_instances(ansible_adhoc):

    for facts in ansible_adhoc().all.ec2_facts():
        if facts['ansible_ec2_placement_region'].startswith('us-east'):
            '''do some testing'''

Parameterizing with pytest.mark.ansible

Perhaps the --ansible-inventory=<inventory> includes many systems, but you only wish to interact with a subset. The pytest.mark.ansible marker can be used to modify the pytest-ansible command-line parameters for a single test. Please note, the fixture ansible_adhoc is the prefer mechanism for interacting with ansible inventory within tests.

For example, to interact with the local system, you would adjust the host_pattern and connection parameters.

@pytest.mark.ansible(host_pattern='local,', connection='local')
def test_copy_local(ansible_module):

    # create a file with random data
    contacted = ansible_module.copy(
        dest='/etc/motd',
        content='PyTest is amazing!',
        owner='root',
        group='root',
        mode='0644',
    )

    # assert only a single host was contacted
    assert len(contacted) == 1, \
        "Unexpected number of hosts contacted (%d != %d)" % \
        (1, len(contacted))

    assert 'local' in contacted

    # assert the copy module reported changes
    assert 'changed' in contacted['local']
    assert contacted['local']['changed']

Note, the parameters provided by pytest.mark.ansible will apply to all class methods.

@pytest.mark.ansible(host_pattern='local,', connection='local')
class Test_Local(object):
    def test_install(self, ansible_module):
        '''do some testing'''
    def test_template(self, ansible_module):
        '''do some testing'''
    def test_service(self, ansible_module):
        '''do some testing'''

Inspecting results

When using the ansible_adhoc, localhost or ansible_module fixtures, the object returned will be an instance of class AdHocResult. The AdHocResult class can be inspected as follows:

def test_adhoc_result(ansible_adhoc):
    contacted = ansible_adhoc(inventory=my_inventory).command("date")

    # As a dictionary
    for (host, result) in contacted.items():
        assert result.is_successful, "Failed on host %s" % host
    for result in contacted.values():
        assert result.is_successful
    for host in contacted.keys():
        assert host in ['localhost', 'one.example.com']

    assert contacted.localhost.is_successful

    # As a list
    assert len(contacted) > 0
    assert 'localhost' in contacted

    # As an iterator
    for result in contacted:
        assert result.is_successful

    # With __getattr__
    assert contacted.localhost.is_successful

    # Or __gettem__
    assert contacted['localhost'].is_successful

Using the AdHocResult object provides ways to conveniently access results for different hosts involved in the ansible adhoc command. Once the specific host result is found, you may inspect the result of the ansible adhoc command on that use by way of the ModuleResult interface. The ModuleResult class represents the dictionary returned by the ansible module for a particular host. The contents of the dictionary depend on the module called.

The ModuleResult interface provides some convenient proprerties to determine the success of the module call. Examples are included below.

def test_module_result(localhost):
    contacted = localhost.command("find /tmp")

    assert contacted.localhost.is_successful
    assert contacted.localhost.is_ok
    assert contacted.localhost.is_changed
    assert not contacted.localhost.is_failed

    contacted = localhost.shell("exit 1")
    assert contacted.localhost.is_failed
    assert not contacted.localhost.is_successful

The contents of the JSON returned by an ansible module differs from module to module. For guidance, consult the documentation and examples for the specific ansible module.

Exception handling

If ansible is unable to connect to any inventory, an exception will be raised.

@pytest.mark.ansible(inventory='unreachable.example.com,')
def test_shutdown(ansible_module):

    # attempt to ping a host that is down (or doesn't exist)
    pytest.raises(pytest_ansible.AnsibleHostUnreachable):
        ansible_module.ping()

Sometimes, only a single host is unreachable, and others will have properly returned data. The following demonstrates how to catch the exception, and inspect the results.

@pytest.mark.ansible(inventory='good:bad')
def test_inventory_unreachable(ansible_module):
    exc_info = pytest.raises(pytest_ansible.AnsibleHostUnreachable, ansible_module.ping)
    (contacted, dark) = exc_info.value.results

    # inspect the JSON result...
    for (host, result) in contacted.items():
        assert result['ping'] == 'pong'

    for (host, result) in dark.items():
        assert result['failed'] == True