# Dapr — Distributed Application Runtime for Cloud and Edge

> Dapr is a portable, event-driven runtime that makes it easy for developers to build resilient, stateless and stateful microservices across cloud and edge environments.

## Install

Save as a script file and run:

# Dapr — Distributed Application Runtime

## Quick Use
```bash
# Install CLI
wget -q https://raw.githubusercontent.com/dapr/cli/master/install/install.sh -O - | /bin/bash

# Initialize Dapr locally (standalone)
dapr init

# Run an app with a Dapr sidecar
dapr run --app-id myapp --app-port 3000 --dapr-http-port 3500 -- python app.py

# Install to Kubernetes
dapr init -k
```

## Introduction
Dapr (Distributed Application Runtime) is a CNCF graduated project that codifies the best practices for building microservice applications into open, independent building blocks. It runs as a sidecar alongside your application so you can call APIs for state, pub/sub, bindings, and actors without reinventing distributed-systems plumbing for every service.

## What Dapr Does
- Provides language-agnostic HTTP/gRPC APIs for service invocation, state management and pub/sub
- Abstracts over dozens of backends (Redis, Kafka, NATS, S3, Postgres, Azure, AWS, GCP)
- Runs as a sidecar so you can bring any language or framework
- Offers virtual actors, workflows and secrets management out of the box
- Integrates with Kubernetes via an operator plus self-hosted mode on a laptop

## Architecture Overview
Each application instance is paired with a Dapr sidecar (daprd) that exposes the building-block APIs over localhost. The sidecar talks to pluggable components defined by YAML (a Redis state store, a Kafka broker, a Vault secret store) and enforces policies like mTLS, retries and access control. On Kubernetes the Dapr control plane (operator, placement, sentry, sidecar-injector) coordinates sidecar injection, actor placement and certificate issuance.

## Self-Hosting & Configuration
- `dapr init` installs the runtime, placement service and bundled Redis/Zipkin locally
- Components are declared in YAML under `~/.dapr/components` or a ConfigMap on K8s
- `dapr init -k` deploys the control plane with Helm into the `dapr-system` namespace
- Configuration CRDs control tracing, metrics, mTLS and middleware pipelines
- Use the `dapr` annotations on Pods to enable sidecar injection automatically

## Key Features
- Building blocks: state, pub/sub, bindings, service invocation, actors, workflows, secrets
- Observability: OpenTelemetry traces, Prometheus metrics and structured logs for every call
- Security: automatic mTLS between sidecars, component-scoped access control, secret-store references
- Resiliency policies: retries, timeouts, circuit breakers declared in YAML
- Workflows authored in code (Go, Python, .NET, Java, JS) backed by durable actors

## Comparison with Similar Tools
- **Istio / Linkerd** — service meshes focused on L7 traffic; Dapr adds app-level APIs (state, pub/sub)
- **Spring Cloud** — Java-only; Dapr is language-agnostic and deploys as a sidecar
- **Temporal** — specialised workflow engine; Dapr workflows are lighter weight but less feature-rich
- **Knative Eventing** — Kubernetes eventing only; Dapr spans self-hosted and edge too
- **NATS / Kafka direct** — Dapr pub/sub hides broker details so you can swap implementations

## FAQ
**Q:** Is Dapr a service mesh?
A: No. Dapr focuses on application-level concerns (state, pub/sub, bindings) and complements meshes that focus on L4/L7 routing.

**Q:** What languages are supported?
A: Anything that can speak HTTP or gRPC. First-party SDKs exist for Go, Python, .NET, Java, JavaScript, PHP and Rust.

**Q:** Can I run Dapr without Kubernetes?
A: Yes. `dapr init` enables a self-hosted mode that is perfect for local development, edge devices or VMs.

**Q:** How does Dapr handle secrets?
A: Components reference a configured secret store (Vault, AWS Secrets Manager, Kubernetes Secrets) so you never embed credentials in YAML.

## Sources
- https://github.com/dapr/dapr
- https://docs.dapr.io

---
Source: https://tokrepo.com/en/workflows/60bcc723-38e6-11f1-9bc6-00163e2b0d79
Author: Script Depot