Python SDK for CloudEvents

Status

This SDK is still considered a work in progress, therefore things might (and will) break with every update.

This SDK current supports the following versions of CloudEvents:

• v1.0
• v0.3

Python SDK

Package cloudevents provides primitives to work with CloudEvents specification: https://github.com/cloudevents/spec.

Installing

The CloudEvents SDK can be installed with pip:

pip install cloudevents

Sending CloudEvents

Below we will provide samples on how to send cloudevents using the popular requests library.

Binary HTTP CloudEvent

from cloudevents.http import CloudEvent, to_binary
import requests

# Create a CloudEvent
# - The CloudEvent "id" is generated if omitted. "specversion" defaults to "1.0".
attributes = {
    "type": "com.example.sampletype1",
    "source": "https://example.com/event-producer",
}
data = {"message": "Hello World!"}
event = CloudEvent(attributes, data)

# Creates the HTTP request representation of the CloudEvent in binary content mode
headers, body = to_binary(event)

# POST
requests.post("<some-url>", data=body, headers=headers)

Structured HTTP CloudEvent

from cloudevents.http import CloudEvent, to_structured
import requests

# Create a CloudEvent
# - The CloudEvent "id" is generated if omitted. "specversion" defaults to "1.0".
attributes = {
    "type": "com.example.sampletype2",
    "source": "https://example.com/event-producer",
}
data = {"message": "Hello World!"}
event = CloudEvent(attributes, data)

# Creates the HTTP request representation of the CloudEvent in structured content mode
headers, body = to_structured(event)

# POST
requests.post("<some-url>", data=body, headers=headers)

You can find a complete example of turning a CloudEvent into a HTTP request in the samples directory.

Receiving CloudEvents

The code below shows how to consume a cloudevent using the popular python web framework flask:

from flask import Flask, request

from cloudevents.http import from_http

app = Flask(__name__)


# create an endpoint at http://localhost:/3000/
@app.route("/", methods=["POST"])
def home():
    # create a CloudEvent
    event = from_http(request.headers, request.get_data())

    # you can access cloudevent fields as seen below
    print(
        f"Found {event['id']} from {event['source']} with type "
        f"{event['type']} and specversion {event['specversion']}"
    )

    return "", 204


if __name__ == "__main__":
    app.run(port=3000)

You can find a complete example of turning a CloudEvent into a HTTP request in the samples directory.

SDK versioning

The goal of this package is to provide support for all released versions of CloudEvents, ideally while maintaining the same API. It will use semantic versioning with following rules:

• MAJOR version increments when backwards incompatible changes is introduced.
• MINOR version increments when backwards compatible feature is introduced INCLUDING support for new CloudEvents version.
• PATCH version increments when a backwards compatible bug fix is introduced.

Community

• There are bi-weekly calls immediately following the Serverless/CloudEvents call at 9am PT (US Pacific). Which means they will typically start at 10am PT, but if the other call ends early then the SDK call will start early as well. See the CloudEvents meeting minutes to determine which week will have the call.
• Slack: #cloudeventssdk channel under CNCF's Slack workspace.
• Email: https://lists.cncf.io/g/cncf-cloudevents-sdk
• Contact for additional information: Denis Makogon (@denysmakogon on slack).

Each SDK may have its own unique processes, tooling and guidelines, common governance related material can be found in the CloudEvents docs directory. In particular, in there you will find information concerning how SDK projects are managed, guidelines for how PR reviews and approval, and our Code of Conduct information.

Maintenance

We use black and isort for autoformatting. We set up a tox environment to reformat the codebase.

e.g.

pip install tox
tox -e reformat

For information on releasing version bumps see RELEASING.md