Pytest System Report

In a previous article, I introduced a simple way to perform system checks with pytest + testinfra . Here it is a simple variant of the same principle with the intention of producing a short human readable report about system configuration. The goal is to get and report quickly some value of interests from a system (a host).

Using Ansible facts

One classic and efficient way to get system information is to use Ansible facts. Here is an example using the ansible ad hoc command.

ansible localhost -m ansible.builtin.setup -a "filter=ansible_kernel"

# localhost | SUCCESS => {
#     "ansible_facts": {
#         "ansible_kernel": "21.2.0"
#     },
#     "changed": false
# }

However Ansible facts may not contain every information you want to check. I find this solution sometimes overkill and not so convenient to obtain a clear output.

Using a table output

I like table outputs in CLI, I think they are very clear. To obtain this kind of output in Python I often use tabulate–the use of tabulate to pretty print Python DataFrame is by far my highest scored answer on Stack Overflow. It is a convenient way to output tables in different formats from various Python data structures.

from typing import List
import pytest
from tabulate import tabulate


@pytest.fixture(scope="session")
def cases():
    return [
        ("Python", "python --version"),
        ("Node", "node --version"),
        ("Rust", "rustc --version | awk '{print $2}'"),
        ("Docker Cli", "docker version --format='{{.Client.Version}}'"),
    ]


def test_summary(host, cases):
    results: List[List] = [["Item", "Info"]]
    for label, command in cases:
        results.append([label, host.check_output(command)])
    print(tabulate(results, headers="firstrow", tablefmt="pretty"))

Then it should be run by

• disabling pytest capture thanks to the -s flag
• reducing pytest verbosity thanks to the -q flag

pytest -s -q system_report.py

# +------------+--------------+
# |    Item    |     Info     |
# +------------+--------------+
# |   Python   | Python 3.9.1 |
# |    Node    |   v16.10.0   |
# |    Rust    |    1.58.1    |
# | Docker Cli |   20.10.12   |
# +------------+--------------+
# .
# 1 passed in 0.39s

This test can be run on any testinfra backends (remote hosts and docker images for example) to get a quick look at some important settings.