Getting started with the Dapr Python gRPC service extension

How to get up and running with the Dapr Python gRPC extension package

The Dapr Python SDK provides a built in gRPC server extension module, dapr.ext.grpc, for creating Dapr services.

Installation

You can download and install the Dapr gRPC server extension module with:

• Stable
• Development

pip install dapr-ext-grpc

Note

The development package will contain features and behavior that will be compatible with the pre-release version of the Dapr runtime. Make sure to uninstall any stable versions of the Python SDK extension before installing the dapr-dev package.

pip3 install dapr-ext-grpc-dev

Examples

The App object can be used to create a server.

Listen for service invocation requests

The InvokeMethodReqest and InvokeMethodResponse objects can be used to handle incoming requests.

A simple service that will listen and respond to requests will look like:

from dapr.ext.grpc import App, InvokeMethodRequest, InvokeMethodResponse
app = App()
@app.method(name='my-method')
def mymethod(request: InvokeMethodRequest) -> InvokeMethodResponse:
    print(request.metadata, flush=True)
    print(request.text(), flush=True)
    return InvokeMethodResponse(b'INVOKE_RECEIVED', "text/plain; charset=UTF-8")
app.run(50051)

A full sample can be found here.

Subscribe to a topic

from cloudevents.sdk.event import v1
from dapr.ext.grpc import App
app = App()
# Default subscription for a topic
@app.subscribe(pubsub_name='pubsub', topic='TOPIC_A')
def mytopic(event: v1.Event) -> None:
    print(event.Data(),flush=True)
# Specific handler using Pub/Sub routing
@app.subscribe(pubsub_name='pubsub', topic='TOPIC_A',
               rule=Rule("event.type == \"important\"", 1))
def mytopic_important(event: v1.Event) -> None:
    print(event.Data(),flush=True)
app.run(50051)

A full sample can be found here.

Setup input binding trigger

from dapr.ext.grpc import App, BindingRequest
app = App()
@app.binding('kafkaBinding')
def binding(request: BindingRequest):
    print(request.text(), flush=True)
app.run(50051)

A full sample can be found here.

Related links

• PyPi