Pod API status code

Introduction

Pod API status code is a Kubernetes pod-level chaos fault that change the API response status code and optionally api response body through path filtering. This is achieved by starting the proxy server and redirecting the traffic through the proxy server.

Use cases

Pod API status code:

• It can be used to test the error handling capabilities of API and client applications. By changing the API response status code to different error codes, such as 400 (Bad Request) or 500 (Internal Server Error), you can evaluate how well your application handles and responds to various error scenarios.
• Simulates situations where the API may be temporarily unavailable or rate-limited by returning temporary error codes like 503 (Service Unavailable) or 429 (Too Many Requests).
• It can be used for content filtering, by selectively filter or block certain responses. For example, you can change the status code to 404 (Not Found) for specific paths or patterns, indicating that the requested resource does not exist.

note

• Kubernetes> 1.17 is required to execute this fault.
• The application pods should be in the running state before and after injecting chaos.

Fault tunables

Mandatory tunables

Tunable	Description	Notes
TARGET_SERVICE_PORT	Port of the target service.	Defaults to port 80. For more information, go to target service port.
STATUS_CODE	Modified status code for the api response	For more information, go to status code .
PATH_FILTER	Api path or route used for the filtering	For more information, go to path filter .

Optional tunables

Tunable	Description	Notes
RESPONSE_BODY	String body to overwrite the HTTP response body. If not provided it will return the original response body	Default: empty body. For more information, go to response body.
PROXY_PORT	Port where the proxy listens for requests.	Default: 20000. For more information, go to proxy port.
SERVICE_DIRECTION	Direction of the flow of control, ingress or egress	Default: `ingress`. For more information, go to service direction .
DATA_DIRECTION	API payload type, request or response	Default: `both`. For more information, go to data direction .
NETWORK_INTERFACE	Network interface used for the proxy.	Default: `eth0`. For more information, go to network interface .
CONTAINER_RUNTIME	Container runtime interface for the cluster	Default: containerd. Support values: docker, containerd and crio. For more information, go to container runtime .
SOCKET_PATH	Path of the containerd or crio or docker socket file.	Default: /run/containerd/containerd.sock. For more information, go to socket path .
TOTAL_CHAOS_DURATION	Duration of chaos injection (in seconds).	Default: 60 s. For more information, go to duration of the chaos .
TARGET_PODS	Comma-separated list of application pod names subject to pod HTTP modify body.	If not provided, the fault selects target pods randomly based on provided appLabels. For more information, go to target specific pods.
PODS_AFFECTED_PERC	Percentage of total pods to target. Provide numeric values.	Default: 0 (corresponds to 1 replica). For more information, go to pod affected percentage .
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30 s. For more information, go to ramp time.
SEQUENCE	Sequence of chaos execution for multiple target pods.	Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.

Target service port

Port of the targeted service. Tune it by using the TARGET_SERVICE_PORT environment variable.

The following YAML snippet illustrates the use of this environment variable:

## provide the port of the targeted service
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-api-status-code
      spec:
        components:
          env:
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            # provide the status code
            - name: STATUS_CODE
              value: "500"
            - name: PATH_FILTER
              value: '/status'   

Status code

Status code to be modified for the HTTP response. Tune it by using the STATUS_CODE environment variable.

The following YAML snippet illustrates the use of this environment variable:

## modified status code for the http response
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-api-status-code
      spec:
        components:
          env:
            # modified status code for the http response
            - name: STATUS_CODE
              value: "500"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            - name: PATH_FILTER
              value: '/status'   

Path Filter

API sub path/route to filter the api calls. Tune it by using the PATH_FILTER environment variable.

The following YAML snippet illustrates the use of this environment variable:

## provide api path filter
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-api-status-code
      spec:
        components:
          env:
            # provide the api path filter
            - name: PATH_FILTER
              value: '/status'
            # provide the status code
            - name: STATUS_CODE
              value: "500"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"         

Advanced Fault Tunables

• PROXY_PORT: Port where the proxy listens for requests and responses
• SERVICE_DIRECTION: Direction of the flow of control, ingress or egress. It supports ingress, egress values.
• DATA_DIRECTION: API payload type, request or response. It supports request, response, and both values.
• NETWORK_INTERFACE: Network interface used for the proxy
• RESPONSE_BODY: It can be used to override the response body. It should be provided in /<regex>/<replacement> format. If not provided it will return the original response body

The following YAML snippet illustrates the use of this environment variable:

# it injects the api modify body fault
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-api-status-code
      spec:
        components:
          env:
            # provide the proxy port
            - name: PROXY_PORT
              value: '20000'
            # provide the connection type
            - name: SERVICE_DIRECTION
              value: 'ingress'
            # provide the payload type
            - name: DATA_DIRECTION
              value: 'both'
            # provide the network interface
            - name: NETWORK_INTERFACE
              value: 'eth0'
            # provide the api path filter
            - name: PATH_FILTER
              value: '/status'
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            - name: STATUS_CODE
              value: "500"
            - name: RESPONSE_BODY
              value: '/.+/test'

Container runtime and socket path

The CONTAINER_RUNTIME and SOCKET_PATH environment variable to set the container runtime and socket file path, respectively.

• CONTAINER_RUNTIME: It supports docker, containerd, and crio runtimes. The default value is containerd.
• SOCKET_PATH: It contains path of containerd socket file by default(/run/containerd/containerd.sock). For docker, specify path as /var/run/docker.sock. For crio, specify path as /var/run/crio/crio.sock.

The following YAML snippet illustrates the use of these environment variables:

## provide the container runtime and socket file path
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-api-status-code
      spec:
        components:
          env:
            # runtime for the container
            # supports docker, containerd, crio
            - name: CONTAINER_RUNTIME
              value: "containerd"
            # path of the socket file
            - name: SOCKET_PATH
              value: "/run/containerd/containerd.sock"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            # provide the api path filter
            - name: PATH_FILTER
              value: '/status'
            - name: STATUS_CODE
              value: "500"