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Circuit Breaker

Circuit Breaking lets you configure failure thresholds that ensure safe maximums after which these requests stop. This allows for a more graceful failure, and time to respond to potential issues before they become larger.

Demo Overview

  • Circuit Breaker is configured in service_red such that Circuit Breaker will be triggered with the following conditions:
    • Envoy makes more than max connection#:1
    • Envoy makes more than max parallel requests#:1

Key definition - clusters in service-envoy-circuitbreaker.yaml

  clusters:
  - name: local_service
    connect_timeout: 0.25s
    type: strict_dns
    lb_policy: round_robin
    circuit_breakers:
      thresholds:
        max_connections: 1
        max_pending_requests: 1
        max_requests: 1
    hosts:
    - socket_address:
        address: 127.0.0.1
        port_value: 8080

For the detail of circuit_breakers configuration, see configuration example and API reference, cluster.CircuitBreakers

Getting Started

git clone https://github.com/yokawasa/envoy-proxy-demos.git
cd envoy-proxy-demos/circuit-breaker

[NOTICE] Before you run this demo, make sure that all demo containers in previous demo are stopped!

Run the Demo

Build and Run containers

docker-compose up --build -d

# check all services are up
docker-compose ps --service

front-envoy
service_green
service_red

# List containers
docker-compose ps
             Name                            Command               State                            Ports
----------------------------------------------------------------------------------------------------------------------------------
circuit-breaker_front-envoy_1     /usr/bin/dumb-init -- /bin ...   Up      10000/tcp, 0.0.0.0:8000->80/tcp, 0.0.0.0:8001->8001/tcp
circuit-breaker_service_green_1   /bin/sh -c /usr/local/bin/ ...   Up      10000/tcp, 80/tcp
circuit-breaker_service_red_1     /bin/sh -c /usr/local/bin/ ...   Up      10000/tcp, 80/tcp

Access and test each services

Access serivce_blue and check if green background page is displayed. It is expected that nothting special will occur.

curl -s http://localhost:8000/service/green

Try paralell access to service_green. It is expected that nothting special will occur. The following helper command allow you to send parallel requests repeatedly (For example, send 5 parallel requests to http://localhost:8000/service/green, each thread make 30 consequent requests).

../helpers/parallel-requests.sh http://localhost:8000/service/green 5

Make at least 5 parallel requests to service_red in order to trigger circit breaker and see a few of requests receive 503 HTTP status code.

../helpers/parallel-requests.sh http://localhost:8000/service/red 5

To make it more conveniently, exclude 200 status code to identify 503 status code easily like this:

../helpers/parallel-requests.sh http://localhost:8000/service/red 5 | grep -v 200

Parallel# 1
Sending GET request: http://localhost:8000/service/red
Parallel# 2
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Parallel# 3
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Parallel# 4
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Parallel# 5
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
503
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
503
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red
Sending GET request: http://localhost:8000/service/red

Stop & Cleanup

docker-compose down --remove-orphans --rmi all

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