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https://github.com/opencitations/oc_ldd

Linked Data Director
https://github.com/opencitations/oc_ldd

Last synced: 4 months ago
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Linked Data Director

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README

          

# OpenCitations LDD Service

[...]

## Configuration

### Environment Variables

The service requires the following environment variables. These values take precedence over the ones defined in `conf.json`:

- `BASE_URL`: Base URL for the service
- `SPARQL_ENDPOINT_INDEX`: URL for the internal Index SPARQL endpoint
- `SPARQL_ENDPOINT_META`: URL for the internal Meta SPARQL endpoint
- `LOG_DIR`: Directory path where log files will be stored
- `SYNC_ENABLED`: Enable/disable static files synchronization (default: false)
- `INDEX_BASE_URL`: Base URL used to construct redirect links for resources served by the application

For instance:

```env
# API Configuration
BASE_URL=api.opencitations.net
LOG_DIR=/home/dir/log/
SPARQL_ENDPOINT_INDEX=http://qlever-service.default.svc.cluster.local:7011
SPARQL_ENDPOINT_META=http://virtuoso-service.default.svc.cluster.local:8890/sparql
SYNC_ENABLED=true
INDEX_BASE_URL=https://w3id.org/oc
```

> **Note**: When running with Docker, environment variables always override the corresponding values in `conf.json`. If an environment variable is not set, the application will fall back to the values defined in `conf.json`.

### Static Files Synchronization

The application can synchronize static files from a GitHub repository. This configuration is managed in `conf.json`:

```json
{
"oc_services_templates": "https://github.com/opencitations/oc_services_templates",
"sync": {
"folders": [
"static",
"html-template/common"
],
"files": [
"test.txt"
]
}
}
```

- `oc_services_templates`: The GitHub repository URL to sync files from
- `sync.folders`: List of folders to synchronize
- `sync.files`: List of individual files to synchronize

When static sync is enabled (via `--sync-static` or `SYNC_ENABLED=true`), the application will:
1. Clone the specified repository
2. Copy the specified folders and files
3. Keep the local static files up to date

> **Note**: Make sure the specified folders and files exist in the source repository.

## Running Options

### Local Development

For local development and testing, the application uses the built-in web.py HTTP server:

Examples:
```bash
# Run with default settings
python3 ldd_oc.py

# Run with static sync enabled
python3 ldd_oc.py --sync-static

# Run on custom port
python3 ldd_oc.py --port 8085

# Run with both options
python3 ldd_oc.py --sync-static --port 8085
```

The application supports the following command line arguments:

- `--sync-static`: Synchronize static files at startup and enable periodic sync (every 30 minutes)
- `--port PORT`: Specify the port to run the application on (default: 8080)

### Production Deployment (Docker)

When running in Docker/Kubernetes, the application uses **Gunicorn** as the WSGI HTTP server for better performance and concurrency handling:

You can change these variables in the Dockerfile:
- **Server**: Gunicorn with gevent workers
- **Workers**: 2 concurrent worker processes
- **Worker Type**: gevent (async) for handling thousands of simultaneous requests
- **Timeout**: 1200 seconds (to handle long-running SPARQL queries)
- **Connections per worker**: 800 simultaneous connections

The Docker container automatically uses Gunicorn and is configured with static sync enabled by default.

> **Note**: The application code automatically detects the execution environment. When run with `python3 ldd_oc.py`, it uses the built-in web.py server. When run with Gunicorn (as in Docker), it uses the WSGI interface.
You can customize the Gunicorn server configuration by modifying the `gunicorn.conf.py` file.

### Dockerfile

You can change these variables in the Dockerfile:

```dockerfile
# Base image: Python slim for a lightweight container
FROM python:3.11-slim

# Define environment variables with default values
# These can be overridden during container runtime
ENV BASE_URL="ldd.opencitations.net" \
LOG_DIR="/mnt/log_dir/oc_ldd" \
SPARQL_ENDPOINT_INDEX="http://qlever-service.default.svc.cluster.local:7011" \
SPARQL_ENDPOINT_META="http://virtuoso-service.default.svc.cluster.local:8890/sparql" \
SYNC_ENABLED="true" \
INDEX_BASE_URL="https://w3id.org/oc"

# Ensure Python output is unbuffered
ENV PYTHONUNBUFFERED=1
# Install system dependencies required for Python package compilation
# We clean up apt cache after installation to reduce image size
RUN apt-get update && \
apt-get install -y \
git \
python3-dev \
build-essential

# Set the working directory for our application
WORKDIR /website

# Clone the specific branch (api) from the repository
# The dot at the end means clone into current directory
RUN git clone --single-branch --branch main https://github.com/opencitations/oc_ldd .

# Install Python dependencies from requirements.txt
RUN pip install -r requirements.txt

# Expose the port that our service will listen on
EXPOSE 8080

# Start the application with gunicorn for production
CMD ["gunicorn", "-c", "gunicorn.conf.py", "ldd_oc:application"]
```