[Day#2 PyATS Series] Setting up Python Virtual Environments for pyATS for Cisco

1. Introduction on the Key Points

In the evolving world of network automation, learning how to integrate Python for Network Engineer tasks has become essential. If you’re a Cisco network professional looking to automate testing, validation, or configuration, pyATS (Python Automated Test System) is your best friend.

In this second article of our multi-day pyATS series, we will walk through setting up a clean and isolated Python virtual environment. This setup allows you to manage dependencies, keep your automation scripts clean, and prepare for real-world projects involving Cisco routers, switches, firewalls, and SD-WAN platforms.

By the end of this article, you will:

• Understand why virtual environments are crucial
• Set up a venv for pyATS using best practices
• Install pyATS core components and verify their versions
• Begin your journey toward automating network testing the right way

2. Topology Overview

Though today’s task is environment setup, here is the logical flow we’ll be using in later labs:

All devices will be accessed via SSH from your local machine using the testbed YAML file (which we’ll preview later).

3. Topology & Communications

We’ll focus on:

• pyATS virtual environment setup
• Installing required modules (pyats, unicon, genie)
• Validating connectivity to testbed (router/switch)

This is the foundation for running real-world tests like interface status checks, configuration drift detection, or ping reachability.

4. Workflow Script

Here’s a simplified script that validates your pyATS environment is set up correctly:

# Step 1: Create Python venv
python3 -m venv pyats_lab_env

# Step 2: Activate it
source pyats_lab_env/bin/activate  # For Linux/macOS
# pyats_lab_env\Scripts\activate   # For Windows

# Step 3: Install pyATS
pip install pyats[full]

# Step 4: Confirm installation
pyats version check

# Optional: Upgrade pip
python -m pip install --upgrade pip

5. Explanation by Line

• python3 -m venv pyats_lab_env: Creates a self-contained environment called pyats_lab_env
• source pyats_lab_env/bin/activate: Activates the environment so that all installations remain isolated
• pip install pyats[full]: Installs the entire pyATS suite, including unicon and genie libraries
• pyats version check: Validates that pyATS and its components are correctly installed

6. testbed.yml Example

testbed:
  name: cisco_testbed
  credentials:
    default:
      username: admin
      password: cisco123

devices:
  R1:
    os: iosxe
    type: router
    connections:
      cli:
        protocol: ssh
        ip: 192.168.1.1

Save this as testbed.yml in your project folder.

7. Post-validation CLI Screenshots (Real expected output)

After installation, run:

pyats version check

Expected output:

| Package      | Version  |
|--------------|----------|
| pyats        | 23.5     |
| unicon       | 23.5     |
| genie        | 23.5     |

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FAQs

Q1: Why should I use a Python virtual environment when working with pyATS?

Answer:
A Python virtual environment isolates your pyATS installation and its dependencies from the system-wide Python setup. This is crucial because:

• It prevents conflicts between different Python packages or versions.
• Allows you to create multiple environments for different projects (e.g., pyATS for Cisco, Ansible automation).
• Keeps your base operating system clean and stable.
• Makes it easier to upgrade or remove pyATS without affecting other Python applications.

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Q2: What Python version should I use for setting up pyATS?

Answer:
Cisco officially supports Python 3.6 to 3.10 for pyATS. It is recommended to use:

• Python 3.8 or 3.9 for maximum compatibility.
• Avoid using Python 3.11+ as some libraries might not yet fully support it.
• You can check your Python version with:

python3 --version

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Q3: How do I create a Python virtual environment for pyATS?

Answer:
Follow these steps:

1. Install Python and venv if not already installed: sudo apt update sudo apt install python3 python3-venv
2. Create a virtual environment: python3 -m venv pyats_venv
3. Activate the environment: source pyats_venv/bin/activate
4. Install pyATS: pip install pyats[full]

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Q4: How do I know my virtual environment is active?

Answer:
When a virtual environment is active:

• Your terminal prompt changes to show the environment name (e.g., (pyats_venv) user@server).
• which python or which pip points to the virtual environment’s directory instead of the system path.
• Any packages installed via pip go into the isolated environment folder.

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Q5: Can I deactivate or remove a virtual environment without affecting pyATS?

Answer:
Yes. To deactivate:

deactivate

To remove the environment completely:

rm -rf pyats_venv

This will not harm your system Python or other projects since everything is contained within the pyats_venv directory.

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Q6: How can I manage multiple virtual environments for different projects?

Answer:
You can create multiple environments, each with different package versions:

python3 -m venv pyats_project1
python3 -m venv pyats_project2

Activate the one you need before running your scripts. Tools like virtualenvwrapper or pyenv can help manage multiple environments easily.

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Q7: What is the difference between venv and virtualenv for pyATS?

Answer:

• venv: Built-in with Python 3.x, simpler to use, no extra installation needed.
• virtualenv: A third-party tool that works for both Python 2 and 3 and offers additional features like faster environment creation.
  For most pyATS use cases, venv is sufficient and recommended.

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Q8: Do I need to activate the virtual environment every time I use pyATS?

Answer:
Yes. Each time you open a new terminal session and want to work with pyATS, you must activate the environment:

source pyats_venv/bin/activate

This ensures you’re using the correct Python interpreter and installed packages.

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YouTube Link

Watch the Complete Python for Network Engineer: Setting up Python Virtual Environments for pyATS (Ping Tests) using pyATS (Vendor-Agnostic) – Cisco, Arista, Palo Alto, Fortigate Lab Demo & Explanation on our channel:

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Join Our Training

If you’re enjoying this hands-on series and want to fast-track your journey into network automation, I invite you to join our 3-month instructor-led training:

Course: Python, Ansible, API & Cisco DevNet for Network Engineers
Check Full Curriculum Here

Led personally by Trainer Sagar Dhawan, this course is designed to:

• Turn you into a confident Python for Network Engineer
• Teach real-world use of pyATS, Ansible, REST APIs
• Build real labs across Cisco, Arista, Palo Alto, Fortigate

Enroll Now & Future‑Proof Your Career
Email: info@networkjourney.com
WhatsApp / Call: +91 97395 21088

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