Needle (cactus-compute): IT Workflow Orchestration

Modern IT automation often requires combining various tools, each excelling in its specific domain. Terraform manages infrastructure, Ansible configures systems, and Python offers flexibility for custom scripts and complex logic. The challenge arises when these tools must work together in a sequential workflow, passing data from one to another. Too often, I found myself writing complex and fragile bash scripts to orchestrate these processes, with the risk of errors and maintenance difficulties. Needle by cactus-compute offers an elegant solution, providing a structured and readable way to define these interactions. When I automated the deployment of a new test environment for a public healthcare organization with 300+ VMware VMs, where VM provisioning was handled by Terraform, OS configuration by Ansible, and post-installation by Python scripts, integrating Needle significantly streamlined the pipeline, reducing debugging time compared to a bash script approach. Needle (cactus-compute) is a lightweight orchestration tool that enables you to define and manage complex workflows integrating Ansible, Terraform, and Python scripts, orchestrating their execution and data transfer via a simple YAML file. Read also: Ansible: Dynamic Inventory Management with Cloud Plugins

Tested on: Ubuntu 24.04 LTS · Needle 0.5.1 · August 2026

Prerequisites / Test Environment

To follow this guide, you will need a Linux system (Ubuntu 22.04+ recommended) with the following tools installed and configured:

• Python 3.8+ and pip for Needle installation.
• Terraform (version 1.0+).
• Ansible (version 2.9+).
• Git for cloning the example repository.

Ensure all these tools are accessible from your system’s PATH.

1. Installing Needle

Needle can be easily installed via pip.

pip install cactus-compute-needle

Verify the installation:

needle --version

You should see output similar to needle, version 0.5.1.

2. Needle Project Structure

A Needle project is primarily defined by a needle.yaml file in the project root. This file describes tasks, their types (Terraform, Ansible, Python), and their dependencies.

Here’s an example needle.yaml that orchestrates infrastructure creation with Terraform, configuration with Ansible, and a final check with Python.

# needle.yaml

version: "1.0"

tasks:
  - name: provision_vms
    type: terraform
    path: ./terraform
    command: apply
    vars:
      instance_count: 2
    outputs:
      - public_ips

  - name: configure_vms
    type: ansible
    path: ./ansible
    playbook: configure_webserver.yml
    inventory:
      plugin: ini
      source: ./ansible/inventory.ini
    vars:
      target_ips: "{{ provision_vms.outputs.public_ips | join(',') }}"
    depends_on: [provision_vms]

  - name: verify_deployment
    type: python
    path: ./scripts/verify_web.py
    args:
      - "--ips"
      - "{{ configure_vms.vars.target_ips }}"
    depends_on: [configure_vms]

In this example:

• provision_vms uses Terraform to create VMs and produces public_ips as output.
• configure_vms uses Ansible, taking the IPs generated by the previous task as input for a target_ips variable and depends on provision_vms.
• verify_deployment is a Python script that receives the configured IPs and verifies the deployment, depending on configure_vms. Read also: Python: Automate Report Generation with Pandas

3. Executing Tasks

To run a specific task, use:

needle run provision_vms

To run all tasks sequentially, respecting dependencies:

needle run all

Needle will manage the execution order and the passing of outputs between tasks. This is particularly useful in development and test environments, where reproducibility is key to validating changes. I’ve used a similar approach to automate the creation of isolated test environments for vulnerability analysis, reducing setup time from hours to minutes.

4. Integrating with Various Tools

Needle natively supports:

• Terraform: apply, plan, destroy, and any other command with variable passing and output capture.
• Ansible: Playbook execution, with dynamic inventory management and extra-vars passing.
• Python: Script execution with command-line arguments.

The flexibility of Needle lies in its ability to enable these tools to communicate without complex intermediate scripts, improving the readability and maintainability of automation code. Read also: Terraform: Manage State Files on S3

Common Errors and Troubleshooting

• PATH Error: Ensure terraform, ansible-playbook, and python are in the PATH where needle is executed. which terraform or which ansible-playbook can help you verify this.
• YAML Syntax: A common error is invalid syntax in needle.yaml. Use needle validate to identify indentation issues or missing keys.
• Unresolved Dependencies: If a task depends on an output from a previous task that has not run or failed, Needle will report it. Check the output of previous tasks for errors.
• Variables Not Passed Correctly: Verify that variable names in vars and outputs match exactly. Debug variable passing by printing values in Python scripts or using Ansible’s --check.

FAQ — Frequently Asked Questions

Does Needle replace AWX or Jenkins?

No, Needle is an orchestrator at the single workflow execution level, not a complete CI/CD system. It can be integrated into CI/CD pipelines managed by Jenkins, GitLab CI, or GitHub Actions to execute complex tasks, but it does not offer features like schedulers, user management, or dashboards.

Can I use Needle to execute arbitrary shell commands?

Directly, no. Needle focuses on integrating Terraform, Ansible, and Python. However, you can always create a Python script that executes shell commands via the subprocess module and then have Needle execute that script.

How does Needle handle task failures?

If a task fails (e.g., Terraform apply fails, Ansible playbook returns an error, Python script exits with a non-zero code), Needle will stop and report the error. This prevents subsequent tasks from running on an inconsistent state, maintaining workflow integrity.

Does Needle support passing sensitive variables?

Needle does not have an integrated mechanism for secrets management like Vault. For sensitive variables, it is recommended to use the standard practices of the integrated tools (e.g., Vault with Terraform/Ansible, environment variables). You can pass these variables to Needle tasks via environment variables or encrypted external files.

Conclusions with Operational Takeaways

Needle by cactus-compute offers a clean and declarative approach to orchestrate complex automation workflows involving Terraform, Ansible, and Python. It eliminates the need for fragile bash scripts, improving pipeline readability and maintainability. It is particularly useful for:

• Test Environments: Creating and destroying complex environments reproducibly.
• Complex Deployments: Managing dependencies between provisioning, configuration, and validation.
• CI/CD Simplification: Integrating multi-tool automation phases into existing pipelines.

Consider Needle if your automation is fragmented across multiple tools and you seek a more elegant way to make them communicate.

Sources

• cactus-compute/needle GitHub Repository