L12 Diac Project

title: "Diagram-as-Code — Complete Project" weight: 12 description: "Apply diagram-as-code skills in a complete project: choose tools, create multiple diagrams, set up CI rendering, version control workflows, and publish a diagrammed documentation page." date: 2026-06-28 lastmod: 2026-06-28 tags: [technical-writing, diagram-as-code] }

The diagram-as-code project applies everything from this course: selecting tools, creating diagrams, setting up CI rendering, implementing version control workflows, and publishing diagrams.

In this lesson, you will combine all lessons into an end-to-end project producing a fully automated diagram pipeline.

What You'll Learn

You will apply tool selection, diagram creation, CI/CD setup, version control workflows, and best practices to create an automated diagram pipeline for a documentation page.

Why It Matters

Theory without practice is worthless. This project forces you to apply every skill. The pipeline you create becomes a template for all future diagram work in your project.

Project Steps

Step 1: Choose Your Tools

Select the right tools for each diagram type:

• Flowcharts: Mermaid
• UML: PlantUML
• Architecture: Structurizr or D2
• Deployment: Diagrams Python library

Step 2: Create Diagram Sources

Create at least 4 diagrams:

1. System architecture (Structurizr or D2)
2. User workflow (Mermaid flowchart)
3. API interaction (Mermaid or PlantUML sequence)
4. Deployment (Diagrams Python)

def project_plan():
    """Generate the project plan."""
    return [
        {"step": 1, "task": "Tool selection", "duration": "30 min"},
        {"step": 2, "task": "Create 4 diagram sources", "duration": "2 hours"},
        {"step": 3, "task": "Set up CI rendering", "duration": "1 hour"},
        {"step": 4, "task": "Configure version control", "duration": "30 min"},
        {"step": 5, "task": "Write documentation page", "duration": "1 hour"},
        {"step": 6, "task": "Review and publish", "duration": "30 min"},
    ]

plan = project_plan()
for p in plan:
    print(f"Step {p['step']}: {p['task']} ({p['duration']})")

Step 3: Set Up CI/CD

Create a GitHub Actions workflow that:

• Validates diagram syntax
• Renders all diagrams to SVG
• Fails on syntax errors
• Deploys rendered diagrams

Step 4: Version Control Setup

• Create the directory structure
• Configure .gitignore for generated files
• Add pre-commit hooks for validation
• Document the workflow

Step 5: Write and Publish

Write a documentation page integrating all diagrams. Include introductory text for each diagram, alt text, and cross-references.

Teacher Mindset

This project is your automation portfolio. You are not just creating diagrams. You are creating a system that produces diagrams automatically, consistently, and correctly every time. That is the skill employers value: not just the ability to draw, but the ability to build processes that keep documentation accurate forever.

Common Mistakes in the Project

1. Trying to Learn All Tools at Once

Focus on 2 tools maximum for this project. Mermaid and one other. Master them before learning additional tools.

2. Skipping CI Setup

Manual rendering works for one diagram. It does not scale. Set up CI from the start. It takes effort upfront but saves hours later.

3. Forgetting to Test the Pipeline

A CI pipeline that fails on the first run is useless. Test the pipeline with a valid diagram, then test with an invalid diagram to verify error handling.

4. No Documentation of the Workflow

If only you know how the diagram pipeline works, it stops working when you are unavailable. Document the setup and process.

5. Overengineering the Setup

A complex pipeline with Docker containers, multiple caches, and parallel jobs is overkill for a small project. Start simple and add complexity as needed.

FAQ

Mini Project

This lesson is the mini project. Complete all steps and publish your diagram pipeline. Write a retrospective on what you learned and what you would improve.

What's Next