NetCDF Explorer

A Flask web application for uploading and analyzing NetCDF3 and NetCDF4 files.

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Table of Contents

1. About The Project
   • Built With
2. Getting Started
   • Prerequisites
   • Installation
3. Usage
4. Configuration
5. Testing
6. Roadmap
7. Contact
8. Acknowledgments

About The Project

NetCDF Explorer (netex) is a web application that allows users to upload and analyze NetCDF3 and NetCDF4 files. It provides a simple interface for viewing file metadata and structure using xarray's HTML representation.

Key features:

• Upload and view NetCDF file summaries including dimensions, coordinates, and variables

Built With

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NetCDF Engines

NetCDF Explorer uses xarray to read uploaded files. Since files are streamed from MinIO into memory, xarray selects a backend engine that supports reading from in-memory buffers. The engine is chosen automatically at runtime based on the file format:

File Format	Engine	Notes
NetCDF3 (classic)	scipy	Handles classic and 64-bit offset NetCDF formats
NetCDF4 / HDF5	h5netcdf	Reads HDF5-based NetCDF4 files via h5py

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Getting Started

To get a local copy up and running, follow these steps.

Prerequisites

• Docker and Docker Compose (for containerized deployment)
• uv (for standalone development)
• Node.js (for Tailwind CSS compilation)

Installation

Docker Compose (Recommended)

1. Clone the repo

   git clone https://github.com/mversaggi/netcdf-explorer.git
   cd netcdf-explorer

2. Start the application with Docker Compose

   docker compose up

3. Access the application at http://localhost:5000

Standalone Development

1. Clone the repo

   git clone https://github.com/mversaggi/netcdf-explorer.git
   cd netcdf-explorer

2. Install Python 3.13 with uv

   uv python install 3.13

3. Install dependencies

   uv sync

4. Build Tailwind CSS

   npm install tailwindcss @tailwindcss/cli
   npx @tailwindcss/cli -i ./static/src/input.css -o ./static/dist/output.css

5. Run the application

   uv run flask --app "src/netex/app:create_app" run

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Usage

1. Navigate to the home page
2. Select a NetCDF file using the file input
3. Click "Explore" to upload the file
4. View the file summary showing dimensions, coordinates, variables, and attributes

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Configuration

Configuration is loaded from a TOML file with environment variable overrides. The config file path is specified by the NETEX_CONFIG environment variable.

Environment Variables

Variable	Description	Default
NETEX_CONFIG	Path to TOML config file	Required
FLASK_DEBUG	Enable Flask debug mode	false
FLASK_SECRET_KEY	Flask session secret key	Required
OBJECT_STORAGE_ENDPOINT	MinIO server endpoint	Required
OBJECT_STORAGE_ACCESS_KEY	MinIO access key	Required
OBJECT_STORAGE_SECRET_KEY	MinIO secret key	Required
OBJECT_STORAGE_SECURE	Use HTTPS for MinIO	false
LOGGER_LEVEL	Logging level (DEBUG, INFO, etc.)	INFO

Example Configuration File

[flask]
debug = true
secret_key = "your_secret_key"

[object_storage]
endpoint = "localhost:9000"
access_key = "minioadmin"
secret_key = "minioadmin"
secure = false

[logger]
level = "info"

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Testing

This project uses pytest for testing.

# Run all tests
uv run pytest

# Run unit tests only
uv run pytest tests/unit/

# Run integration tests only (requires Docker for MinIO container)
uv run pytest tests/integration/

# Run with coverage
uv run pytest --cov=src --cov-report=html:tests/reports

Code Formatting

# Format Python code
uv run black src/ tests/

# Format Jinja2 templates
uv run djlint templates/ --reformat

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Roadmap

• File upload and storage in MinIO
• Organized summary view of file
• Variable visualization on globe
• View saved files

See the open issues for a full list of proposed features and known issues.

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Contact

Project Link: https://github.com/mversaggi/netcdf-explorer

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Acknowledgments

• xarray - N-D labeled arrays and datasets in Python
• Best-README-Template - README template

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