Install Codex CLI with Ollama

Step-by-step guide to installing and configuring the OpenAI Codex CLI with local Ollama models for offline AI coding assistance.

Difficulty: 🟡 Intermediate
Estimated Time: 15-20 minutes
Prerequisites: Node.js, Basic command line knowledge, Ubuntu/Debian system

What You'll Learn

This tutorial covers essential AI coding setup concepts and tools:

Codex CLI Installation - Setting up OpenAI's command-line coding assistant
Ollama Integration - Configuring local LLM models for offline use
Local Development Setup - Creating a secure, private AI coding environment
Workflow Integration - Using AI assistance in your development process

Prerequisites

Node.js and npm installed
Basic command line knowledge
Ubuntu/Debian system
curl utility

VS Code Extensions - Enhance your development environment
Docker GPU Setup - Containerize your AI development environment
Security Best Practices - Secure your development workflow

Introduction

Welcome to the world of local AI coding assistance! In this guide, you'll learn how to install the Codex CLI from OpenAI Codex and configure it to use the powerful Ollama provider for local LLM execution. This integration is perfect if you're looking for offline, high-performance AI coding assistance without cloud dependencies.

Understanding Codex CLI

What is OpenAI Codex CLI?

The OpenAI Codex CLI is an open-source command-line tool that brings the power of OpenAI's latest reasoning models directly to your terminal. It acts as a lightweight coding agent that can:

Read, modify, and run code on your local machine
Help you build features faster
Squash bugs efficiently
Understand unfamiliar code

It runs entirely locally, so your code stays secure and private unless you choose to share it.

Key Features

Zero-setup install: npm install -g @openai/codex
Multimodal inputs: text, screenshots, diagrams
Rich approval workflow: Suggest, Auto Edit, Full Auto
Terminal-based: Works fully in the terminal for fast iteration

Approval Modes

Mode	What It Can Do	When to Use
Suggest	Proposes edits & commands, requires approval	Safe exploration & code review
Auto Edit	Reads/writes files, asks before running commands	Repetitive or refactoring tasks
Full Auto	Full autonomy in a sandboxed environment	Long builds or automated prototyping

Pro tip: Codex warns before entering Auto modes if the directory isn't under version control!

Installation Steps

Step 1: Install Ollama (Ubuntu Edition)

curl -fsSL https://ollama.com/install.sh | sh
ollama --version
sudo systemctl enable ollama
sudo systemctl start ollama

Troubleshooting:

sudo apt install curl
chmod +x install.sh && ./install.sh

Step 2: Install Codex CLI Globally

curl -fsSL https://deb.nodesource.com/setup_22.x | sudo bash -
sudo apt install -y nodejs
sudo apt install -y npm
sudo npm install -g @openai/codex

Step 3: Run Ollama Locally

ollama pull qwen3
ollama run qwen3

Ollama runs on http://localhost:11434

Step 4: Create Your Codex Config File

nano ~/.codex.json

Paste the following configuration:

{
  "model": "qwen3",
  "provider": "Ollama",
  "providers": {
    "ollama": {
      "name": "Ollama",
      "baseURL": "http://localhost:11434/v1",
      "envKey": "OLLAMA_API_KEY"
    }
  },
  "history": {
    "maxSize": 1000,
    "saveHistory": true,
    "sensitivePatterns": []
  }
}

Using Codex CLI

Start Coding with Codex CLI

codex generate a python hello world

Example Usage

> codex
Enter prompt: Generate a Python function to fetch data from an API.

Troubleshooting Common Issues

Ollama Connection Issues

Ollama not responding: Ensure it's running on localhost:11434
Model not found: Use ollama pull qwen3
Command not found: Ensure Codex CLI was installed globally

Node.js Installation Issues

Permission denied: Use sudo for global npm installations
Version conflicts: Ensure you're using Node.js 22.x or later

Conclusion

You've successfully set up a local AI coding assistant! The Codex CLI with Ollama integration provides you with powerful, offline AI coding capabilities while maintaining the privacy and security of your code.

Key Takeaways:

Codex CLI offers powerful local AI coding assistance
Ollama provides offline LLM capabilities
Local setup ensures code privacy and security

Next Steps:

Explore different Ollama models for various coding tasks
Integrate Codex into your daily development workflow
Consider setting up version control for safer Auto mode usage

Tags: #Codex #Ollama #AICoding #LocalLLM #CLI #Development #OpenAI #NodeJS #Ubuntu

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