Dapr - CMDSheet

Introduction

Dapr (Distributed Application Runtime) is an open-source project that simplifies the development of microservices-based applications by providing building blocks such as state management, pub/sub messaging, and service invocation. This blog explores essential Dapr commands that every developer should know.

Installation

dapr --version

To verify the installation

Initializing Dapr

dapr init	Initialize it locally
dapr init --kubernetes	To initialize Dapr in Kubernetes mode
dapr uninstall	To uninstall Dapr
dapr uninstall --kubernetes	To uninstall from Kubernetes

Managing Dapr Applications

• Running a Dapr Application

dapr run --app-id myapp --app-port 5000 --dapr-http-port 3500 -- python app.py

• --app-id specifies a unique identifier for the app.
• --app-port defines the port where the app runs.

• --dapr-http-port assigns a port for Dapr sidecar HTTP communication.

• Stopping a Running Dapr App

dapr stop --app-id myapp

Viewing Dapr Application Status

dapr list	To list running Dapr instances
dapr logs --app-id myapp	To check the logs of a running Dapr application

State Management Commands

dapr state get statestore mykey	To get the state from a state store
dapr state save statestore mykey "myvalue"	To save a state
dapr state delete statestore mykey	To delete a state

Service Invocation

• Dapr enables service-to-service communication. To invoke a method on another service:

curl -X POST http://localhost:3500/v1.0/invoke/myservice/method/mymethod -d '{"data":"hello"}' -H "Content-Type: application/json"

• Or using the Dapr CLI:

dapr invoke --app-id myservice --method mymethod --post --data '{"data":"hello"}'

Pub/Sub Messaging

• To publish an event:

dapr publish --pubsub pubsub --topic mytopic --data '{"message": "hello world"}'

• To subscribe to a topic, define a subscriber service that listens for events.

Observability & Debugging

dapr components -k	Checking Component Status
dapr config -k	Checking Configuration

Enabling Tracing

• Enable tracing with the following:

dapr run --app-id myapp --app-port 5000 --enable-metrics --enable-tracing -- python app.py

Dapr Dashboard

dapr dashboard	To start the Dapr dashboard
dapr dashboard -k	If running in Kubernetes

Conclusion

Dapr CLI commands make it easy to develop, debug, and manage microservices. Whether you’re running applications locally or in Kubernetes, these commands will help you interact with Dapr’s features efficiently. Happy coding!