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Documentation Grafana k6 Testing guides Injecting faults with xk6-disruptor Expose your application

Expose your application

To access your application from the test scripts, you must assign it an external IP in the cluster where it’s running. How you do this depends on the platform you use to deploy the application. The following sections explain the different approaches.

Using port-forwarding

kubectl’s port-forward command allows accessing applications running in a Kubernetes cluster using a local port.

For example, the following command will make my-service’s port 80 accessible as localhost:8080:

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kubectl port-forward svc/my-service 8080:80
Forwarding from 127.0.0.1:8080 -> 80

Limitations using port forwarding

To be able to inject faults, xk6-disruptor must install an agent on each target that intercepts the requests and applies the desired disruptions. This process requires any existing connection to the targets to be redirected to the agent.

Due to an existing bug in kubectl, the process of installing the disruptor can potentially break the port forwarding. Notice that this issue happens only if the faults are injected in the service that is exposed using port forward. If the faults are injected in another service not exposed by port-forwarding, there shouldn’t be any issue.

Until this issue is solved in kubectl, tests using port forwarding to access a service should ensure the agent is installed in the targets before any traffic is sent by the test.

The simplest way to accomplish this is to ensure the scenario that executes the load (#2) starts after the scenario that injects the faults (#1):

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    scenarios: {
        disrupt: {   // #1 inject faults
            executor: 'shared-iterations',
            iterations: 1,
            vus: 1,
            exec: "disrupt",
            startTime: "0s",
        },
        load: {   // #2 execute load
            executor: 'constant-arrival-rate',
            rate: 100,
            preAllocatedVUs: 10,
            maxVUs: 100,
            exec: "default",
            startTime: '20s',  // give time for the agents to be installed
            duration: "30s",
        }
     }

As a LoadBalancer service

A service of type LoadBalancer receives an external IP from an external load-balancer provider. How you configure the load balancer depends on the your cluster’s deployment platform and configuration. The following sections provide guidelines to expose your application when running in common development environments. If your cluster is deployed in a public cloud, check your cloud provider documentation.

If the service that you want your tests to access is not defined as a load balancer, you can change the service type with the following command. The service will then receive an external IP.

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kubectl -n <name space> patch svc <service name> -p '{"spec": {"type": "LoadBalancer"}}'

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kubectl -n <name space> patch svc <service name> -p '{\"spec\": {\"type\": \"LoadBalancer\"}}'

You can retrieve the external IP address and store it in an environment variable (SVC_IP in this example) using the following command:

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SVC_IP=$(kubectl -n <name space>  get svc <service name> --output jsonpath='{.status.loadBalancer.ingress[0].ip}')

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$Env:SVC_IP=$(kubectl -n <name space>  get svc <service name> --output jsonpath='{.status.loadBalancer.ingress[0].ip}')

Configuring a LoadBalancer in Kind

Kind is a tool to run local Kubernetes clusters using a Docker container to emulate nodes. You can use kind for local development or CI. Services deployed in a kind cluster can be exposed to be accessed from the host machine using metallb as a load balancer.

Configuring a LoadBalancer in Minikube

Minikube implements a local Kubernetes cluster that supports different technologies to virtualize the cluster’s infrastructure, such as containers, VMs or bare metal.

Minikube’s tunnel command runs as a process, creating a network route on the host to the service CIDR of the cluster. It uses the cluster’s IP address as a gateway. The tunnel command exposes the external IP directly to any program that is running on the host operating system.

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minikube tunnel