litmus/pod-http-latency.md at master

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Introduction

It injects http response latency on the service whose port is provided as TARGET_SERVICE_PORT by starting proxy server and then redirecting the traffic through the proxy server.
It can test the application's resilience to lossy/flaky http responses.

!!! tip "Scenario: Add latency to the HTTP request"

Uses

??? info "View the uses of the experiment" coming soon

Prerequisites

??? info "Verify the prerequisites" - Ensure that Kubernetes Version > 1.17 - Ensure that the Litmus Chaos Operator is running by executing kubectl get pods in operator namespace (typically, litmus).If not, install from here - Ensure that the pod-http-latency experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. If not, install from here

Default Validations

??? info "View the default validations" The application pods should be in running state before and after chaos injection.

Minimal RBAC configuration example (optional)

!!! tip "NOTE" If you are using this experiment as part of a litmus workflow scheduled constructed & executed from chaos-center, then you may be making use of the litmus-admin RBAC, which is pre installed in the cluster as part of the agent setup.

??? note "View the Minimal RBAC permissions"

    ```yaml
    ---
    apiVersion: v1
    kind: ServiceAccount
    metadata:
      name: pod-http-latency-sa
      namespace: default
      labels:
        name: pod-http-latency-sa
        app.kubernetes.io/part-of: litmus
    ---
    apiVersion: rbac.authorization.k8s.io/v1
    kind: Role
    metadata:
      name: pod-http-latency-sa
      namespace: default
      labels:
        name: pod-http-latency-sa
        app.kubernetes.io/part-of: litmus
    rules:
      # Create and monitor the experiment & helper pods
      - apiGroups: [""]
        resources: ["pods"]
        verbs: ["create","delete","get","list","patch","update", "deletecollection"]
      # Performs CRUD operations on the events inside chaosengine and chaosresult
      - apiGroups: [""]
        resources: ["events"]
        verbs: ["create","get","list","patch","update"]
      # Fetch configmaps details and mount it to the experiment pod (if specified)
      - apiGroups: [""]
        resources: ["configmaps"]
        verbs: ["get","list",]
      # Track and get the runner, experiment, and helper pods log
      - apiGroups: [""]
        resources: ["pods/log"]
        verbs: ["get","list","watch"]
      # for creating and managing to execute comands inside target container
      - apiGroups: [""]
        resources: ["pods/exec"]
        verbs: ["get","list","create"]
      # deriving the parent/owner details of the pod(if parent is anyof {deployment, statefulset, daemonsets})
      - apiGroups: ["apps"]
        resources: ["deployments","statefulsets","replicasets", "daemonsets"]
        verbs: ["list","get"]
      # deriving the parent/owner details of the pod(if parent is deploymentConfig)
      - apiGroups: ["apps.openshift.io"]
        resources: ["deploymentconfigs"]
        verbs: ["list","get"]
      # deriving the parent/owner details of the pod(if parent is deploymentConfig)
      - apiGroups: [""]
        resources: ["replicationcontrollers"]
        verbs: ["get","list"]
      # deriving the parent/owner details of the pod(if parent is argo-rollouts)
      - apiGroups: ["argoproj.io"]
        resources: ["rollouts"]
        verbs: ["list","get"]
      # for configuring and monitor the experiment job by the chaos-runner pod
      - apiGroups: ["batch"]
        resources: ["jobs"]
        verbs: ["create","list","get","delete","deletecollection"]
      # for creation, status polling and deletion of litmus chaos resources used within a chaos workflow
      - apiGroups: ["litmuschaos.io"]
        resources: ["chaosengines","chaosexperiments","chaosresults"]
        verbs: ["create","list","get","patch","update","delete"]
    ---
    apiVersion: rbac.authorization.k8s.io/v1
    kind: RoleBinding
    metadata:
      name: pod-http-latency-sa
      namespace: default
      labels:
        name: pod-http-latency-sa
        app.kubernetes.io/part-of: litmus
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: Role
      name: pod-http-latency-sa
    subjects:
    - kind: ServiceAccount
      name: pod-http-latency-sa
      namespace: default
    ```
    Use this sample RBAC manifest to create a chaosServiceAccount in the desired (app) namespace. This example consists of the minimum necessary role permissions to execute the experiment.

Experiment tunables

??? info "check the experiment tunables"

Mandatory Fields

<table>
  <tr>
    <th> Variables </th>
    <th> Description </th>
    <th> Notes </th>
  </tr>
  <tr>
    <td> TARGET_SERVICE_PORT </td>
    <td> Port of the service to target</td>
    <td>Defaults to port 80 </td>
  </tr>
  <tr>
    <td> LATENCY  </td>
    <td> Latency value in ms to be added to requests</td>
    <td> Defaults to 2000 </td>
  </tr>
</table>

<h2>Optional Fields</h2>

<table>
  <tr>
    <th> Variables </th>
    <th> Description </th>
    <th> Notes </th>
  </tr>
  <tr>
    <td> PROXY_PORT  </td>
    <td> Port where the proxy will be listening for requests</td>
    <td> Defaults to 20000 </td>
  </tr>
  <tr>
    <td> NETWORK_INTERFACE  </td>
    <td> Network interface to be used for the proxy</td>
    <td> Defaults to `eth0` </td>
  </tr>
  <tr>
    <td> TOXICITY </td>
    <td> Percentage of HTTP requests to be affected </td>
    <td> Defaults to 100 </td>
  </tr>
  <tr>
    <td> CONTAINER_RUNTIME  </td>
    <td> container runtime interface for the cluster</td>
    <td> Defaults to containerd, supported values: docker, containerd and crio for litmus and only docker for pumba LIB </td>
  </tr>
  <tr>
    <td> SOCKET_PATH </td>
    <td> Path of the containerd/crio/docker socket file </td>
    <td> Defaults to `/run/containerd/containerd.sock` </td>
  </tr>
  <tr>
    <td> TOTAL_CHAOS_DURATION </td>
    <td> The duration of chaos injection (seconds) </td>
    <td> Default (60s) </td>
  </tr>
  <tr>
    <td> TARGET_PODS </td>
    <td> Comma separated list of application pod name subjected to pod http latency chaos</td>
    <td> If not provided, it will select target pods randomly based on provided appLabels</td>
  </tr>
  <tr>
    <td> PODS_AFFECTED_PERC </td>
    <td> The Percentage of total pods to target  </td>
    <td> Defaults to 0 (corresponds to 1 replica), provide numeric value only </td>
  </tr>
  <tr>
    <td> LIB_IMAGE  </td>
    <td> Image used to run the netem command </td>
    <td> Defaults to `litmuschaos/go-runner:latest` </td>
  </tr>
  <tr>
    <td> RAMP_TIME </td>
    <td> Period to wait before and after injection of chaos in sec </td>
    <td> </td>
  </tr>
  <tr>
    <td> SEQUENCE </td>
    <td> It defines sequence of chaos execution for multiple target pods </td>
    <td> Default value: parallel. Supported: serial, parallel </td>
  </tr>
</table>

Experiment Examples

Common and Pod specific tunables

Refer the common attributes and Pod specific tunable to tune the common tunables for all experiments and pod specific tunables.

Target Service Port

It defines the port of the targeted service that is being targeted. It can be tuned via TARGET_SERVICE_PORT ENV.