VMware HTTP latency

VMware HTTP latency injects HTTP response latency into the service whose port is specified using the TARGET_SERVICE_PORT environment variable. This is achieved by starting the proxy server and redirecting the traffic through the proxy server.

• It helps determine the application's resilience to lossy (or flaky) HTTP responses.

Usage

View the uses of the fault

This fault helps determine how resilient an application is to HTTP latency. It helps determine how the system recovers or fetches the responses when there is a delay in accessing the service. It simulates latency to specific API services for (or from) a given microservice. It also simulates a slow response on specific third party (or dependent) components (or services).

Prerequisites

• Kubernetes >= 1.17
• Vcenter access to stop and start the VM.
• Kubernetes secret that has the Vcenter credentials in the CHAOS_NAMESPACE. Below is a sample secret file:

apiVersion: v1
kind: Secret
metadata:
    name: vcenter-secret
    namespace: litmus
type: Opaque
stringData:
    VCENTERSERVER: XXXXXXXXXXX
    VCENTERUSER: XXXXXXXXXXXXX
    VCENTERPASS: XXXXXXXXXXXXX

Note

You can pass the VM credentials as secrets or as a ChaosEngine environment variable.

Default validations

The VM should be in a healthy state.

Fault tunables

Fault tunables

Mandatory fields

Variables	Description	Notes
VM_NAME	Name of the VMware VM.	For example, test-vm.
VM_USER_NAME	Username with sudo privileges.	For example, vm-user.
VM_PASSWORD	User password.	For example, 1234.
LATENCY	Delay added to the request (in milliseconds).	For example, 1000ms.
TARGET_SERVICE_PORT	Service port to target.	Defaults to port 80.

Optional fields

Variables	Description	Notes
TOTAL_CHAOS_DURATION	Duration that you specify, through which chaos is injected into the target resource (in seconds).	Defaults to 30s.
CHAOS_INTERVAL	Time interval between two successive instance terminations (in seconds).	Defaults to 30s.
SEQUENCE	Sequence of chaos execution for multiple instances.	Defaults to parallel. Supports serial sequence as well.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30s.
INSTALL_DEPENDENCY	Whether to install the dependency to run the fault	If the dependency already exists, you can turn it off. Its default value is 'True'.
PROXY_PORT	Port where the proxy listens for requests.	Defaults to 20000.
TOXICITY	Percentage of HTTP requests affected.	Defaults to 100.
NETWORK_INTERFACE	Network interface used for the proxy.	Defaults to eth0.

Fault examples

Common fault tunables

Refer to the common attributes to tune the common tunables for all the faults.

Target service port

It defines the port of the target service. You can tune it using the TARGET_SERVICE_PORT environment variable.

Use the following example to tune it:

## provide the port of the targeted service
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: VMware-http-latency
    spec:
      components:
        env:
        # provide the port of the targeted service
        - name: TARGET_SERVICE_PORT
          value: "80"

Proxy Port

It defines the port where the proxy server listens for requests. You can tune it using the PROXY_PORT environment variable.

Use the following example to tune it:

# provide the port for proxy server
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: VMware-http-latency
    spec:
      components:
        env:
        # provide the port for proxy server
        - name: PROXY_PORT
          value: '8080'
        # provide the port of the targeted service
        - name: TARGET_SERVICE_PORT
          value: "80"

Latency

It defines the latency value added to the HTTP request. You can tune it using the LATENCY environment variable.

Use the following example to tune it:

## provide the latency value
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: VMware-http-latency
    spec:
      components:
        env:
        # provide the latency value
        - name: LATENCY
          value: '2000'
        # provide the port of the targeted service
        - name: TARGET_SERVICE_PORT
          value: "80"

Toxicity

It defines the toxicity value added to the HTTP request. Toxicity value defines the percentage of the total number of HTTP requests that are affected. You can tune it using the TOXICITY environment variable.

Use the following example to tune it:

## provide the toxicity
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: VMware-http-latency
    spec:
      components:
        env:
        # toxicity is the probability of the request to be affected
        # provide the percentage value in the range of 0-100
        # 0 means no request will be affected and 100 means all request will be affected
        - name: TOXICITY
          value: "100"
        # provide the port of the targeted service
        - name: TARGET_SERVICE_PORT
          value: "80"

Network interface

It defines the network interface to be used for the proxy. You can tune it using the NETWORK_INTERFACE environment variable.

Use the following example to tune it:

## provide the network interface for proxy
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: VMware-http-latency
    spec:
      components:
        env:
        # provide the network interface for proxy
        - name: NETWORK_INTERFACE
          value: "eth0"
        # provide the port of the targeted service
        - name: TARGET_SERVICE_PORT
          value: '80'