OnedataRESTFSSpec

OnedataRESTFSSpec is an fsspec filesystem implementation for Onedata, providing a unified interface for accessing Onedata spaces using Python fsspec API.

Features

• Full fsspec compatibility
• Support for reading and writing files
• Directory operations (list, create, remove)
• File metadata access
• Authentication via access tokens
• Environment variable configuration
• URI-based configuration
• OpenTelemetry metrics export

Installation

Install from PyPi:

pip install onedatarestfsspec

Install from the local directory:

pip install -e ./onedatarestfsspec

Requirements

• Python >= 3.10
• fsspec >= 2021.10.0
• onedatafilerestclient >= 25.0.0
• aiohttp

Usage

Basic Usage

import fsspec

# Using explicit parameters
fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://datahub.egi.eu',
    token='your_access_token'
)

# List spaces
spaces = fs.ls('/')
print("Available spaces:", spaces)

# List files in a space
files = fs.ls('/your-space/')
print("Files in space:", files)

# Read a file
with fs.open('/your-space/path/to/file.txt', 'rb') as f:
    content = f.read()

# Write a file
with fs.open('/your-space/path/to/newfile.txt', 'wb') as f:
    f.write(b'Hello, Onedata!')

# Get file info
info = fs.info('/your-space/path/to/file.txt')
print("File size:", info['size'])

For a full example see here.

Environment Variables

Set environment variables for automatic configuration:

export ONEDATA_ONEZONE_HOST="https://datahub.egi.eu"
export ONEDATA_TOKEN="your_access_token"
export ONEDATA_PREFERRED_PROVIDERS="provider1.example.com,provider2.example.com"
export ONEDATA_VERIFY_SSL="true"
export ONEDATA_TIMEOUT="30"

Then use without explicit parameters:

import fsspec

# Configuration will be loaded from environment variables
fs = fsspec.filesystem('onedata')

URL-based Configuration

import fsspec

# URL format: onedata://token@onezone_host/path?query_params
url = "onedata://your_token@datahub.egi.eu/your-space/path/to/file.txt"

# Open file directly from URL
with fsspec.open(url, 'r') as f:
    content = f.read()

Advanced Usage

import fsspec

fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://datahub.egi.eu',
    token='your_access_token',
    preferred_providers=['provider1.example.com'],
    verify_ssl=True,
    timeout=60,
    auto_mkdir=True  # Automatically create parent directories
)

# Copy files
fs.cp('/your-space/source.txt', '/your-space/destination.txt')

# Upload local file
fs.put('/local/path/file.txt', '/your-space/remote/file.txt')

# Download file
fs.get('/your-space/remote/file.txt', '/local/path/downloaded.txt')

# Create directory
fs.makedirs('/your-space/new/directory')

# Remove file
fs.rm('/your-space/file/to/remove.txt')

# Check if file exists
if fs.exists('/your-space/some/file.txt'):
    print("File exists!")

# Get detailed listing
files = fs.ls('/your-space/', detail=True)
for file_info in files:
    print(f"{file_info['name']}: {file_info['size']} bytes")

OpenTelemetry Metrics

OnedataRESTFSSpec can export data-access metrics to any OpenTelemetry-compatible collector (Prometheus, Grafana Tempo, Jaeger, etc.) using the OTLP protocol.

Installation

Metrics support is an optional feature. Install the HTTP exporter (recommended) or the gRPC exporter, or both:

# HTTP/protobuf transport (default)
pip install 'onedatarestfsspec[monitoring]'

# gRPC transport only
pip install opentelemetry-exporter-otlp-proto-grpc

Enabling metrics

Metrics are disabled by default. Enable them either via a constructor keyword argument or an environment variable:

import fsspec

fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://datahub.egi.eu',
    token='your_access_token',
    metrics_enabled=True,
)

export ONEDATA_METRICS_ENABLED=true

Configuring the OTLP exporter

The exporter is configured through standard OpenTelemetry environment variables or the corresponding constructor keyword arguments. Keyword arguments take precedence over environment variables.

Constructor kwarg	Environment variable	Default	Description
metrics_enabled	ONEDATA_METRICS_ENABLED	false	Enable metrics export
otlp_endpoint	OTEL_EXPORTER_OTLP_METRICS_ENDPOINT	collector default	Full URL of the OTLP collector endpoint
otlp_protocol	OTEL_EXPORTER_OTLP_PROTOCOL	http/protobuf	Transport protocol: http/protobuf or grpc
otlp_export_interval_ms	—	60000	How often metrics are flushed (milliseconds)
otlp_session_id	ONEDATA_OTLP_SESSION_ID	auto-generated UUID	Session identifier attached to every metric as the session_id attribute. Useful for correlating metrics from a single run across restarts or multiple filesystem instances.

Example — HTTP/protobuf transport:

import fsspec

fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://dev-onezone.default.svc.cluster.local',
    token='your_access_token',
    metrics_enabled=True,
    verify_ssl=False,
    otlp_endpoint='http://localhost:9090/api/v1/otlp/v1/metrics',
    otlp_protocol='http/protobuf',
    otlp_export_interval_ms=30_000,
)

Example — pinning a session ID:

In order to make it easier to identify sets of metrics collected from a specific OnedataRESTFSSpec client, it's possible to add otlp_session_id parameter to the constructor with custom ID representing an OnedataRESTFSSpec session:

import fsspec

fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://datahub.egi.eu',
    token='your_access_token',
    metrics_enabled=True,
    otlp_session_id='my-experiment-run-1',
)

# Retrieve the active session ID (auto-generated when not set explicitly)
print(fs.otlp_session_id)

Alternatively the session id can be specified using an environment variable:

export ONEDATA_OTLP_SESSION_ID=my-experiment-run-1

Example — gRPC transport via environment variables:

export ONEDATA_METRICS_ENABLED=true
export OTEL_EXPORTER_OTLP_PROTOCOL=grpc
export OTEL_EXPORTER_OTLP_METRICS_ENDPOINT=http://otel-collector.example.com:4317

fs = fsspec.filesystem(
    'onedata',
    onezone_host='https://datahub.egi.eu',
    token='your_access_token',
)

Available metrics

All metrics carry the following attributes, allowing time-series to be filtered and grouped by space, file, session, or operation type:

Attribute	Description
space_id	Onedata space identifier
file_id	Onedata internal file identifier
provider_id	Domain of the Oneprovider that served the request
session_id	Identifier for this filesystem instance's session (see otlp_session_id)
operation	"read" or "write"

Metric name	Type	Unit	Description
onedata_file_access_total	Counter	ops	Total number of read and write operations. Use the operation attribute to distinguish reads from writes.
onedata_read_bytes	Counter	bytes	Cumulative bytes read from Onedata.
onedata_written_bytes	Counter	bytes	Cumulative bytes written to Onedata.
onedata_read_duration	Histogram	seconds	Per-operation read latency.
onedata_write_duration	Histogram	seconds	Per-operation write latency.
onedata_file_throughput_bytes_per_second	Histogram	bytes/s	Observed transfer throughput (bytes / duration) for each operation.

Example: querying metrics in Prometheus

After scraping via an OpenTelemetry Collector with a Prometheus exporter, the metrics are available under their original names (dots replaced by underscores where required by Prometheus).

# Read throughput (bytes/s) averaged over 5 minutes, by space
rate(onedata_read_bytes_total[5m]) by (space_id)

# 99th-percentile read latency per file
histogram_quantile(0.99, rate(onedata_read_duration_bucket[5m])) by (file_id)

# Write operation rate
rate(onedata_file_access_total[1m]) by (space_id, operation)

# Total bytes read for a specific session
sum(onedata_read_bytes_total{session_id="my-experiment-run-1"})

Path Format

Paths in OnedataRESTFSSpec follow the format: /space-name/path/within/space

• Root path / lists all available spaces
• Space path /space-name refers to the root of a specific space
• File path /space-name/dir/file.txt refers to a file within a space

onedatarestfsspec client also supports URI-based paths, i.e. specifying onedata:///space-name/path/within/space when opening a file or directory using generic fsspec calls such as:

 f = fsspec.open('onedata:///MySpace/file.txt')

will automatically select onedatarestfsspec client to open the file via Onedata, provided that the necessary parameters are provided (see here).

Configuration Priority

Configuration is resolved in the following order (highest to lowest priority):

1. Explicit parameters passed to fsspec.filesystem()
2. URL parameters (when using URL-based access)
3. Environment variables

Error Handling

OnedataRESTFSSpec translates Onedata REST API errors to standard Python exceptions:

• FileNotFoundError for missing files/directories
• IOError for general I/O errors
• ValueError for invalid parameters
• PermissionError for access denied errors

Limitations

• Cross-space file operations are not supported
• Symbolic links are treated as regular files

Development

To set up for development:

# Install dependencies
pip install -e ./onedatafilerestclient
pip install -e ./onedatarestfsspec[test]

# Run tests
pytest onedatarestfsspec/tests/

# Run with coverage
pytest --cov=onedatarestfsspec onedatarestfsspec/tests/

License

This project is licensed under the MIT License - see the LICENSE file for details.