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Dapr Resiliency: Service Invoke

In this QuickStart, you will run two microservice applications. One microservice (checkout) will continuously make Dapr service invocation requests to the other microservice (order-processor). When requests begin to fail, Dapr resiliency policies are applied.

Visit the documentation about Dapr resiliency link for more information

This quickstart includes one service:

  • Caller service checkout
  • Callee service order-processor
  • Resiliency spec resiliency.yaml

Run both services with Dapr and resiliency enabled

  1. Open two terminal windows. In one terminal window, navigate to the checkout service. In the other terminal window, navigate to the order-processor service. Install dependencies for each service and run both services with resiliency enabled:

C# example

Order Processor Service:
cd ../service_invocation/csharp/http/order-processor
dotnet restore
dotnet build
dapr run --app-port 7001 --app-id order-processor --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3501 -- dotnet run
Checkout Service:
cd ../service_invocation/csharp/http/checkout
dotnet restore
dotnet build
dapr run  --app-id checkout --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3500 -- dotnet run

Go example

Order Processor Service:
cd ../service_invocation/go/http/order-processor
go build .
dapr run --app-port 6001 --app-id order-processor --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3501 -- go run .
Checkout Service:
cd ../service_invocation/go/http/checkout
go build .
dapr run  --app-id checkout --resources-path ../../../resources/  --app-protocol http --dapr-http-port 3500 -- go run .

Java example

Order Processor Service
cd ../service_invocation/java/http/order-processor
mvn clean install
dapr run --app-id order-processor --resources-path ../../../resources/ --app-port 9001 --app-protocol http --dapr-http-port 3501 -- java -jar target/OrderProcessingService-0.0.1-SNAPSHOT.jar
Checkout Service
cd ../service_invocation/java/http/checkout
mvn clean install
dapr run --app-id checkout --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3500 -- java -jar target/CheckoutService-0.0.1-SNAPSHOT.jar

JavaScript example

Order Processor Service
cd ../service_invocation/javascript/http/order-processor
npm install
dapr run --app-port 5001 --app-id order-processor --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3501 -- npm start
Checkout Service
cd ../service_invocation/javascript/http/checkout
npm install
dapr run  --app-id checkout --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3500 -- npm start

Python example

Order Processor Service
cd ../service_invocation/python/http/order-processor
pip3 install -r requirements.txt
dapr run --app-port 8001 --app-id order-processor --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3501 -- python3 app.py
Checkout Service
cd ../service_invocation/python/http/checkout
pip3 install -r requirements.txt
dapr run  --app-id checkout --resources-path ../../../resources/ --app-protocol http --dapr-http-port 3500 -- python3 app.py

Expected output

Once both services are running, the order-processor service will recieve orders from the checkoutservice continuously using Dapr's service invoke API.

order-processor output
== APP == Order received: { orderId: 1 }
== APP == Order received: { orderId: 2 }
== APP == Order received: { orderId: 3 }

Simulate ann application failure by stopping the order-processor service

Simulate a system failure by stopping the order-processor service running in your second terminal window.

CTRL + C

Observe retry and circuit breaker policies are applied

Policies defined in the resiliency.yaml spec:

retryForever:
  policy: constant
  duration: 5s
  maxRetries: -1

circuitBreakers:
  simpleCB:
  maxRequests: 1
  timeout: 5s
  trip: consecutiveFailures >= 5
Applied policies
INFO[0005] Error processing operation endpoint[order-processor, order-processor:orders]. Retrying...
INFO[0025] Circuit breaker "order-processor:orders" changed state from closed to open
INFO[0030] Circuit breaker "order-processor:orders" changed state from open to half-open
INFO[0030] Circuit breaker "order-processor:orders" changed state from half-open to open

Simulate the application recovering by restarting the order-processor service:

Simulate the order-processor service recovering by restarting the application using the dapr run command:

C# example

Order Processor Service
dapr run --app-port 7001 --app-id order-processor --resources-path --app-protocol http --dapr-http-port 3501 -- dotnet run

Go example

Order Processor Service
dapr run --app-port 6001 --app-id order-processor --resources-path --app-protocol http --dapr-http-port 3501 -- go run .

Java example

Order Processor Service
dapr run --app-id order-processor --resources-path --app-port 9001 --app-protocol http --dapr-http-port 3501 -- java -jar target/OrderProcessingService-0.0.1-SNAPSHOT.jar

JavaScript example

Order Processor Service
dapr run --app-port 5001 --app-id order-processor --resources-path --app-protocol http --dapr-http-port 3501 -- npm start

Python example

Order Processor Service:
dapr run --app-port 8001 --app-id order-processor --resources-path --app-protocol http --dapr-http-port 3501 -- python3 app.py

Observe orders have resumed sequentially:

order-processor output:
== APP == Order received: { orderId: 4 }
== APP == Order received: { orderId: 5 }
== APP == Order received: { orderId: 6 }
== APP == Order received: { orderId: 7 }

Stop the apps with Dapr

dapr stop --app-id order-processor
dapr stop --app-id checkout