This document provides an introduction to Dapr (Distributed Application Runtime), an open-source project initiated by Microsoft for building distributed applications. It discusses Dapr's architecture, building blocks like service invocation, pub/sub, state management and secrets APIs. It also covers hosting environments, SDKs, performance, pros and cons and deployment in Kubernetes with annotations.

1. Introduction to Dapr (Distributed Application
Runtime)
Yevhen Bova
2021-02-25

2. 2
www.luxoft.com
Short bio
 Java Developer at Luxoft
 10 years of experience in Java
 Involved in the development of:
 A huge OSGI-baseddesktop application(600+ modules, 300+ third-partymodules)
 Server-side - microservices

4. 4
www.luxoft.com
Project overview
 https://dapr.io/
 Initiated by Microsoft
 Open-source project (MIT License) - https://github.com/dapr/dapr
 Initial version: 0.1 released in Oct 2019
 Current version: v1.0 released on Feb 17

5. 5
www.luxoft.com
High-level architecture diagram

6. 6
www.luxoft.com
Building blocks (API)

7. 7
www.luxoft.com
Hosting environments
• Self-hosted
• Dapr runtime needs to be launched via CL
• Kubernetes-hosted
• Dapr side-car container injected into pod

8. 8
www.luxoft.com
Self-hosted

9. 9
www.luxoft.com
Kubernetes-hosted

10. 10
www.luxoft.com
Launching locally
dapr run --app-id myservice
--app-port 8081
--app-protocol http
-- java -Dserver.port=8081 -jar com.example.myservice.jar

11. 11
www.luxoft.com
Service invocation API
Overview

12. 12
www.luxoft.com
Service invocation API
Features
• All calls between Dapr applications can be made secure with mutual authentication (mTLS)
• Supports calls across namespaces
• Performs retries
• Observability
• All calls between applications are traced, and metrics are gathered to provide insights and diagnostics for applications
• Uses W3C tracing context
• Integrates with OpenTelemetry for tracing, metrics, and logs
• Access Control Lists

13. 13
www.luxoft.com
Pub/sub API
Overview

14. 14
www.luxoft.com
Pub/sub API
The same file can be applied
• locally
• in k8s
Configuration

15. 15
www.luxoft.com
Pub/sub API
Features
• Guarantees at-least-once semantics for message delivery
• Multiple subscribers with the same app ID
• Message delivered to one instance
• Multiple subscribers with different app ID
• Message delivered to all subscribers
• Topic scoping
• Limit which application can publish or subscribe to topics
• Messages are wrapped in CloudEvent format (if not already wrapped)

16. 16
www.luxoft.com
Pub/sub API
Components
• Hazelcast
• Redis Streams (5.0.0 or later)
• NATS
• Kafka
• Azure Service Bus
• RabbitMQ
• Azure Event Hubs
• GCP Pub/Sub
• MQTT
• Possible to provide custom backend via SPI

17. 17
www.luxoft.com
State management API
Overview

18. 18
www.luxoft.com
State management API
Features
• Consistency
• eventual consistency (default behavior)
• strong consistency
• Concurrency
• first-write-wins (ETag support is required either by store or through Dapr emulation)
• last-write-wins
• Bulk operations
• not transactional
• transactional

19. 19
www.luxoft.com
State management API
Components
Name CRUD
Transactional
(Supports Actors)
ETag
Aerospike ✅ ❌ ✅
Apache Cassandra ✅ ❌ ❌
Cloudstate ✅ ❌ ✅
Couchbase ✅ ❌ ✅
Hashicorp Consul ✅ ❌ ❌
Hazelcast ✅ ❌ ❌
Memcached ✅ ❌ ❌
MongoDB ✅ ✅ ❌
MySQL ✅ ✅ ✅
PostgreSQL ✅ ✅ ✅
Redis ✅ ✅ ✅
RethinkDB ✅ ✅ ✅
Zookeeper ✅ ❌ ✅
AWS, GCP, Azure stores…

20. 20
www.luxoft.com
State management API
Components
• Dapr supports Redis 5 and later
• Azure supports Redis 4 and 6

21. 21
www.luxoft.com
Bindings API
Overview

22. 22
www.luxoft.com
Bindings API
Components
Name
Input
Binding
Output
Binding
Status
Apple Push Notifications (APN) ✅ Alpha
Cron (Scheduler) ✅ ✅ Alpha
HTTP ✅ GA
InfluxDB ✅ Alpha
Kafka ✅ ✅ Alpha
Kubernetes Events ✅ Alpha
MQTT ✅ ✅ Alpha
MySQL ✅ Alpha
PostgreSql ✅ Alpha
Postmark ✅ Alpha
RabbitMQ ✅ ✅ Alpha
Redis ✅ Alpha
SMTP ✅ Alpha
Twilio ✅ Alpha
Twitter ✅ ✅ Alpha
SendGrid ✅ Alpha
AWS, GCP, Azure, Alibaba…

23. 23
www.luxoft.com
Secrets API
Overview

24. 24
www.luxoft.com
Secrets API
Features
• Can be accessed
• Programmatically through API
• In Dapr component configuration files
• Secrets scoping
• By default, any secret is accessible from any Dapr application
• Each Dapr application can be configured to have access to only selected secrets

25. 25
www.luxoft.com
Secrets API
Components
• Local environment variables
• Local file
• HashiCorp Vault
• Kubernetes secrets
• AWS Secret Manager
• GCP Secret Manager
• Azure Key Vault

26. 26
www.luxoft.com
SDKs
Language Status Client SDK
Service
Extensions
Actor SDK
.NET Stable ✔
✔
ASP.NET Core
✔
Python Stable ✔
✔
gRPC
✔
FastAPI
Flask
Java Stable ✔
✔
Spring Boot
✔
Go Stable ✔ ✔
PHP Stable ✔ ✔ ✔
C++ In development ✔
Rust In development ✔
Javascript In development ✔

27. 27
www.luxoft.com
Performance and scalability
Workflow

28. 28
www.luxoft.com
Performance and scalability
Overhead
Test setup:
• 1,000 requests per second
• Sidecar limited to 0.5 vCPU
• Sidecar mTLS enabled
• Sidecar telemetry enabled (tracing with a sampling rate of 0.1)
• Payload of 1KB
• Dapr side car overhead (1,000 requests):
• 0.48 vCPU
• 23Mb
• Control plane consumes:
• In non-HA mode: 0.009 vCPU and 61.6 Mb
• In HA mode: ~0.02 vCPU and 185 Mb

29. 29
www.luxoft.com
Performance and scalability
Latency

30. 30
www.luxoft.com
Pros
 Simple workflows with pub/sub and stage management are easy to implement with Dapr
 No need to deal with different third-party SDK, drivers, etc.
 Encourages developers to use best practices
 Implementation of a component (store, pub-sub, etc) can be replaced easily
 Language-agnostic
 Well-documented
 API examples
 SDK examples
 Deployment examples

31. 31
www.luxoft.com
Cons
 APIs provide a small subset of features of underlying components
 Restricts versions of underlying components
 Only Redis 5 and 6 are supported
 Makes it harder to launch/debug apps on the dev side
 Need to launch two processes instead of one (app + Dapr)
 Console log is cluttered
 No good support in IDE (yet?)
 Devs have to create launchers manually to launch Dapr
 Requires extra resources on server side (two-four pods)
 Adds complexity to the overall picture
 Overlaps with istio: mTLS, tracing
 Maturity status:
 A lot of components are in alpha/experimental state
 Low adaptation

32. 32
www.luxoft.com
References
Good overview - https://www.youtube.com/watch?v=MjyulcRqh20
Examples - https://github.com/dapr/quickstarts
SDK examples - https://github.com/dapr/java-sdk/tree/master/examples/src/main/java/io/dapr/examples
API reference - https://docs.dapr.io/reference/api/
Service Invocation Performance - https://docs.dapr.io/operations/performance-and-scalability/perf-service-invocation/

33. Thank You!

35. 35
www.luxoft.com
Deployment in Kubernetes
Overview

36. 36
www.luxoft.com
Deployment in Kubernetes
Annotations

37. 37
www.luxoft.com
IDE support