Consul Service Mesh Example for HashiCorp Learn

These assets are provided to show how to configure Envoy outlier detection in HashiCorp Consul to implement a circuit breaker for an application in a service mesh.

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Requirements

• Docker Compose
• Docker
• curl

Demo Script Guide

The following files are provided as demo scripts:

• start.sh: Starts Consul, three services (web, api-v1, api-v2) with proxies, and Prometheus (for metrics).
• fail.sh: Enables error rates for api-v2 service.
• success.sh: Disables error rates for api-v2 service for successful calls.
• request.sh: Make repeated API calls to the web service to trigger the circuit breaker.
• cleanup.sh: Removes all of the instances.

Demo Workflow

NOTE: DON'T FORGET that this demo requires Docker Compose!

1. Run start.sh. This starts Consul in development mode and registers three services, web, api-v1, and api-v2. It also starts Prometheus to aggregate metrics.

2. Run fail.sh. This toggles an error setting in api-v2 to mimic an error.

3. Run request.sh to issue 100 API requests against the web service. Since outlier detection is enabled, you will find that the circuit breaker will open and divert all traffic to api-v1 while occasionally sending a request to api-v2 to check its availability.

4. In another terminal, run success.sh. This will close the circuit breaker and once more divert traffic to both api-v1 and api-v2.

Finally, run cleanup.sh to re-set your environment so that you can repeat the demo as necessary.

WARNING: The cleanup.sh removes all instances.