Pod API modify body

Introduction

Pod API modify body is a Kubernetes pod-level chaos fault that modifies the api request and response body by replacing any portions that match a specified regular expression with a provided value. This is achieved by starting the proxy server and redirecting the traffic through the proxy server.

Use cases

Pod API modify body:

• It can be used for API testing, by replacing specific portions of the request or response body to simulate different scenarios and validate how your application handles different data variations.
• Simulate error conditions and test the error handling capabilities of API by replacing specific patterns in the response body with error messages or custom error codes to test error handling and reporting mechanisms are in place.
• It can be useful for obscuring or redacting personally identifiable information (PII), such as email addresses or phone numbers, before logging or transmitting the data for security and privacy compliance.

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
RESPONSE_BODY	String body to overwrite the HTTP response body.	If no value is provided, response will be an empty body. Defaults to empty body. For more information, go to response body
PATH_FILTER	Api path or route used for the filtering	For more information, go to path filter

Optional tunables

Tunable	Description	Notes
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-modify-body
      spec:
        components:
          env:
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            # provide the body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "/.+/test"
            - name: PATH_FILTER
              value: '/status'   

Response body

String body that overwrites the API request and response body. Tune it by using the RESPONSE_BODY environment variable.

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

## provide the response body value
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-modify-body
      spec:
        components:
          env:
            # provide the body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "/.+/test"
            - name: PATH_FILTER
              value: '/status'   
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"

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-modify-body
      spec:
        components:
          env:
            # provide the api path filter
            - name: PATH_FILTER
              value: '/status'
            - name: RESPONSE_BODY
              value: "/.+/test"
            # 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

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-modify-body
      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: 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-modify-body
      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: RESPONSE_BODY
              value: "/.+/test"