fastapi-cloudevents

FastAPI plugin for CloudEvents Integration

Allows to easily consume and produce CloudEvents over REST API.

Automatically parses CloudEvents both in the binary and structured format and provides an interface very similar to the regular FastAPI interface. No more hustling with to_structured and from_http function calls!

@app.post("/")
async def on_event(event: CloudEvent) -> CloudEvent:
   pass

See more examples below

Install

pip install fastapi-cloudevents

Examples

Simple Example

import uvicorn
from fastapi import FastAPI

from fastapi_cloudevents import CloudEvent, install_fastapi_cloudevents

app = FastAPI()
app = install_fastapi_cloudevents(app)


@app.post("/")
async def on_event(event: CloudEvent) -> CloudEvent:
    return CloudEvent(
        type="my.response-type.v1",
        data=event.data,
        datacontenttype=event.datacontenttype,
    )


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

The rout accepts both binary CloudEvents

curl http://localhost:8000 -i -X POST -d "Hello World!" \
  -H "Content-Type: text/plain" \
  -H "ce-specversion: 1.0" \
  -H "ce-type: my.request-type.v1" \
  -H "ce-id: 123" \
  -H "ce-source: my-source"

And structured CloudEvents

curl http://localhost:8000 -i -X POST -H "Content-Type: application/json" \
  -d '{"data":"Hello World", "source":"my-source", "id":"123", "type":"my.request-type.v1","specversion":"1.0"}'

Both of the requests will yield a response in the same format:

HTTP/1.1 200 OK
date: Fri, 05 Aug 2022 23:50:52 GMT
server: uvicorn
content-length: 13
content-type: application/json
ce-specversion: 1.0
ce-id: 25cd28f0-0605-4a76-b1d8-cffbe3375413
ce-source: http://localhost:8000/
ce-type: my.response-type.v1
ce-time: 2022-08-05T23:50:52.809697+00:00

"Hello World"

CloudEvent Type Routing

from typing import Literal, Union

import uvicorn
from fastapi import FastAPI, Body
from pydantic import Field
from typing_extensions import Annotated

from fastapi_cloudevents import (
    CloudEvent,
    CloudEventSettings,
    ContentMode,
    install_fastapi_cloudevents,
)

app = FastAPI()
app = install_fastapi_cloudevents(
    app, settings=CloudEventSettings(default_response_mode=ContentMode.structured)
)


class MyEvent(CloudEvent):
    type: Literal["my.type.v1"]


class YourEvent(CloudEvent):
    type: Literal["your.type.v1"]


OurEvent = Annotated[Union[MyEvent, YourEvent], Body(discriminator="type")]

_source = "dummy:source"


@app.post("/")
async def on_event(event: OurEvent) -> CloudEvent:
    if isinstance(event, MyEvent):
        return CloudEvent(
            type="my.response-type.v1",
            data=f"got {event.data} from my event!",
            datacontenttype="text/plain",
        )
    else:
        return CloudEvent(
            type="your.response-type.v1",
            data=f"got {event.data} from your event!",
            datacontenttype="text/plain",
        )


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8002)

Structured Response Example

To send the response in the http CloudEvent structured format, you MAY use the BinaryCloudEventResponse class

import uvicorn
from fastapi import FastAPI

from fastapi_cloudevents import (CloudEvent, StructuredCloudEventResponse,
                                 install_fastapi_cloudevents)

app = FastAPI()
app = install_fastapi_cloudevents(app)


@app.post("/", response_class=StructuredCloudEventResponse)
async def on_event(event: CloudEvent) -> CloudEvent:
    return CloudEvent(
        type="com.my-corp.response.v1",
        data=event.data,
        datacontenttype=event.datacontenttype,
    )


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8001)

curl http://localhost:8001 -i -X POST -d "Hello World!" \
  -H "Content-Type: text/plain" \
  -H "ce-specversion: 1.0" \
  -H "ce-type: my.request-type.v1" \
  -H "ce-id: 123" \
  -H "ce-source: my-source"

HTTP/1.1 200 OK
date: Fri, 05 Aug 2022 23:51:26 GMT
server: uvicorn
content-length: 247
content-type: application/json

{"data":"Hello World!","source":"http://localhost:8001/","id":"3412321f-85b3-4f7f-a551-f4c23a05de3a","type":"com.my-corp.response.v1","specversion":"1.0","time":"2022-08-05T23:51:26.878723+00:00","datacontenttype":"text/plain"}