Fetch Dynamic Prompts from GitHub and Auto-Populate n8n Expressions in Prompt

Who Is This For?

This workflow is designed for AI engineers, automation specialists, and content creators who need a scalable system to dynamically manage prompts stored in GitHub. It eliminates manual updates, enforces required variable checks, and ensures that AI interactions always receive fully processed prompts.

🚀 What Problem Does This Solve?

Manually managing AI prompts can be inefficient and error-prone. This workflow:
✅ Fetches dynamic prompts from GitHub
✅ Auto-populates placeholders with values from the setVars node
✅ Ensures all required variables are present before execution
✅ Processes the formatted prompt through an AI agent

🛠 How This Workflow Works

This workflow consists of three key branches, ensuring smooth prompt retrieval, variable validation, and AI processing.

1️⃣ Retrieve the Prompt from GitHub (HTTP Request → Extract from File → SetPrompt)

• The workflow starts manually or via an external trigger.
• It fetches a text-based prompt stored in a GitHub repository.
• The Extract from File Node retrieves the content from the GitHub file.
• The SetPrompt Node stores the prompt, making it accessible for processing.

📌 Note:
The prompt must contain n8n expression format variables (e.g., {{ $json.company }}) so they can be dynamically replaced.

2️⃣ Extract & Auto-Populate Variables (Check All Prompt Vars → Replace Variables)

• A Code Node scans the prompt for placeholders in the n8n expression format ({{ $json.variableName }}).
• The workflow compares required variables against the setVars node:
  • ✅ If all variables are present, it proceeds to variable replacement.
  • ❌ If any variables are missing, the workflow stops and returns an error listing them.
• The Replace Variables Node replaces all placeholders with values from setVars.

📌 Example of a properly formatted GitHub prompt:

Hello {{ $json.company }}, your product {{ $json.features }} launches on {{ $json.launch_date }}.

This ensures seamless replacement when processed in n8n.

3️⃣ AI Processing & Output (AI Agent → Prompt Output)

• The Set Completed Prompt Node stores the final, processed prompt.
• The AI Agent Node (Ollama Chat Model) processes the prompt.
• The Prompt Output Node returns the fully formatted response.

📌 Optional: Modify this to use OpenAI, Claude, or other AI models.

⚠️ Error Handling: Missing Variables

If a required variable is missing, the workflow stops execution and provides an error message:

⚠️ Missing Required Variables: ["launch_date"]

This ensures no incomplete prompts are sent to AI agents.

✅ Example Use Case

📜 GitHub Prompt File (Using n8n Expressions)

Hello {{ $json.company }}, your product {{ $json.features }} launches on {{ $json.launch_date }}.

🔹 Variables in setVars Node

{
  "company": "PropTechPro",
  "features": "AI-powered Property Management",
  "launch_date": "March 15, 2025"
}

✅ Successful Output

Hello PropTechPro, your product AI-powered Property Management launches on March 15, 2025.

🚨 Error Output (If Missing launch_date)

⚠️ Missing Required Variables: ["launch_date"]

🔧 Setup Instructions

1️⃣ Connect Your GitHub Repository

• Store your prompt in a public or private GitHub repo.
• The workflow will fetch the raw file using the GitHub API.

2️⃣ Configure the SetVars Node

• Define the required variables in the SetVars Node.
• Make sure the variable names match those used in the prompt.

3️⃣ Test & Run

• Click Test Workflow to execute.
• If variables are missing, it will show an error.
• If everything is correct, it will output the fully formatted prompt.

⚡ How to Customize This Workflow

💡 Need CRM or Database Integration?

• Connect the setVars node to an Airtable, Google Sheets, or HubSpot API to pull variables dynamically.

💡 Want to Modify the AI Model?

• Replace the Ollama Chat Model with OpenAI, Claude, or a custom LLM endpoint.

📌 Why Use This Workflow?

✅ No Manual Updates Required – Fetches prompts dynamically from GitHub.
✅ Prevents Broken Prompts – Ensures required variables exist before execution.
✅ Works for Any Use Case – Handles AI chat prompts, marketing messages, and chatbot scripts.
✅ Compatible with All n8n Deployments – Works on Cloud, Self-Hosted, and Desktop versions.