VMware HTTP latency

VMware HTTP latency injects HTTP response latency into the service of a specific port.

• 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.

Use cases

• VMware HTTP latency determines the resilience of an application to HTTP latency.
• It determines 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 is required to execute this fault.
• Appropriate vCenter permissions should be provided to start and stop the VMs.
• The VM should be in a healthy state before and after injecting chaos.
• Kubernetes secret has to be created that has the Vcenter credentials in the CHAOS_NAMESPACE. VM credentials can be passed as secrets or as a ChaosEngine environment variable. 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

Mandatory tunables

Tunable	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. For more information, go to latency.
TARGET_SERVICE_PORT	Service port to target.	Defaults to port 80. For more information, go to target service port.

Optional tunables

Tunable	Description	Notes
TOTAL_CHAOS_DURATION	Duration that you specify, through which chaos is injected into the target resource (in seconds).	Defaults to 30s. For more information, go to duration of the chaos.
CHAOS_INTERVAL	Time interval between two successive instance terminations (in seconds).	Defaults to 30s. For more information, go to chaos interval.
SEQUENCE	Sequence of chaos execution for multiple instances.	Defaults to parallel. Supports serial sequence as well. For more information, go to sequence of chaos execution.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30s. For more information, go to ramp time.
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. For more information, go to proxy port.
TOXICITY	Percentage of HTTP requests affected.	Defaults to 100. For more information, go to toxicity.
NETWORK_INTERFACE	Network interface used for the proxy.	Defaults to eth0. For more information, go to network interface.
DEFAULT_HEALTH_CHECK	Determines if you wish to run the default health check which is present inside the fault.	Default: 'true'. For more information, go to default health check.

Target service port

It specifies the port of the target service. Tune it by 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 specifies the port where the proxy server listens for requests. Tune it by 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 specifies the latency value added to the HTTP request. Tune it by 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 specifies the toxicity value added to the HTTP request. Toxicity value defines the percentage of the total number of HTTP requests that are affected. Tune it by 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 specifies the network interface to be used for the proxy. Tune it by 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'