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Install Python Requirements

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Python dependencies for Ansible playbooks can be installed using either a requirements.txt file that installs packages at runtime, or by building a custom Docker image with dependencies pre-installed. Choose the requirements.txt approach for quick prototyping and frequently changing dependencies, or use custom images for production workloads requiring faster execution and strict reproducibility.

Before you begin​

Before you begin, make sure the following are in place:

  • Harness IaCM pipeline configured: You need an existing pipeline with the IACMAnsiblePlugin step. Go to Get started with Ansible to configure your first Ansible pipeline.
  • Playbook repository with Git connector: Your playbooks must be stored in a Git repository with a configured Harness connector. Go to Connect to a code repository to set up a Git connector.
  • Understanding of Python package names: You should know which Python packages your playbooks require. Go to PyPI to search for Python packages.

Install using requirements.txt​

This approach installs Python dependencies at the start of each pipeline run using a requirements.txt file in your playbook repository.

Create requirements.txt​

Create a requirements.txt file in your playbook repository with your required Python packages:

tabulate==0.9.0
netaddr==0.9.0
jmespath==1.0.1

Pin versions using == to ensure reproducibility across pipeline runs.

Add pipeline variable​

In your Harness pipeline, add a pipeline variable to point to your requirements file:

  1. Open your pipeline in the Harness UI.
  2. Select Variables in the pipeline editor.
  3. Add a new variable with the following values:
    • Name: ANSIBLE_REQUIREMENTS
    • Type: String
    • Value: requirements.txt

If your requirements file is in a subdirectory, provide the relative path from the repository root:

path/to/requirements.txt

Run your pipeline​

When the pipeline runs, dependencies are installed automatically before your playbook executes. Check the pipeline logs to verify installation:

────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
  🧰 Install python requirements                                                                                        
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

ansible-playbook resolved to: /usr/local/bin/ansible-playbook
ansible-playbook interpreter: /usr/bin/python3.11
Installing python requirements from /harness/requirements.txt using /usr/bin/python3.11 (pip --user)
✓ ok: requirements installed

Complete example​

This example demonstrates using the tabulate package installed via requirements.txt:

Directory structure:

my-playbook-repo/
├── requirements.txt
├── playbook.yml
└── inventory.ini

requirements.txt:

tabulate==0.9.0

playbook.yml:

---
- name: Test tabulate package
  hosts: localhost
  gather_facts: false
  
  tasks:
    - name: Use tabulate to format data
      ansible.builtin.shell: |
        python3.11 << 'EOF'
        from tabulate import tabulate
        data = [["Name", "Age"], ["Alice", 30], ["Bob", 25]]
        print(tabulate(data, headers="firstrow"))
        EOF
      register: result
    
    - name: Display result
      ansible.builtin.debug:
        msg: "{{ result.stdout }}"

Pipeline variable:

  • Name: ANSIBLE_REQUIREMENTS
  • Value: requirements.txt

The ANSIBLE_REQUIREMENTS variable is automatically detected and dependencies are installed before the playbook runs.

Install using custom images​

Custom images pre-install Python dependencies in a Docker image, eliminating installation time on every pipeline run. When using custom images, do not set the ANSIBLE_REQUIREMENTS variable because dependencies are already in the image.

Go to Using custom images to learn how to build and use custom execution environment images.

Next steps​

Now that you understand how to install Python requirements, explore related topics: