Pod API modify body

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.

Pod API Modify Body

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.

Prerequisites

Kubernetes> 1.17
The application pods should be in the running state before and after injecting chaos.

Mandatory tunables

Tunable	Description	Notes
TARGET_CONTAINER	Name of the container subject to API body modification.	None. For more information, go to target specific container
TARGET_SERVICE_PORT	Port of the target service.	Defaults to port 80. For more information, go to target service port
NODE_LABEL	Node label used to filter the target node if `TARGET_NODE` environment variable is not set.	It is mutually exclusive with the `TARGET_NODE` environment variable. If both are provided, the fault uses `TARGET_NODE`. For more information, go to node label.
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
LIB_IMAGE	Image used to inject chaos.	Default: `chaosnative/chaos-go-runner:main-latest`. For more information, go to image used by the helper pod.
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
DESTINATION_PORTS	comma-separated list of the destination service or host ports for which `egress` traffic should be affected	Default: 80,8443. For more information, go to destination ports
HTTPS_ENABLED	facilitate HTTPS support for both incoming and outgoing traffic	Default: false. For more information, go to https
CUSTOM_CERTIFICATES	Provide the custom certificates for the proxy server to serve as intermediate certificates for HTTPS communication	The HTTPS communications necessitate its use as intermediate certificates by the proxy server. These same certificates must also be loaded into the target application. For more information, go to HTTPS
HTTPS_ROOT_CERT_PATH	Provide the root CA certificate directory path	This setting must be configured if the root CA certificate directory differs from /etc/ssl/certs. Please refer to https://go.dev/src/crypto/x509/root_linux.go to understand the default certificate directory based on various Linux distributions. For more information, go to HTTPS
HTTPS_ROOT_CERT_FILE_NAME	Provide the root CA certificate file name	This setting must be configured if the root CA certificate file name differs from ca-certificates.crt. Please refer to https://go.dev/src/crypto/x509/root_linux.go to understand the default certificate file names based on various Linux distributions. For more information, go to HTTPS
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 target 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 (or 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"         

Destination ports

A comma-separated list of the destination service or host ports for which egress traffic should be affected as a result of chaos testing on the target application. Tune it by using the DESTINATION_PORTS environment variable.

note

It is applicable only for the egress SERVICE_DIRECTION.

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

## provide destination ports
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 destination ports
            - name: DESTINATION_PORTS
              value: '80,443'
            # 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"        

HTTPS

Enable the HTTPS support for both incoming and outgoing traffic by setting the HTTPS_ENABLED field to true. Its usage varies depending on whether it's applied to ingress or egress scenarios.

Ingress

Set this parameter if the HTTPS URL of the target application includes a port, formatted as https://<hostname>:port. However, if the HTTPS URL is in the format https://<hostname> without a port, this setting is not required.

Egress

For outbound traffic, setting HTTPS_ENABLED to true is required to enable HTTPS support for external services. This enables the establishment of TLS certificates for the proxy within the target application.

If the HTTP client in the target application is configured to reload certificates with each API call, set HTTPS_ENABLED to true, and there's no need to provide CUSTOM_CERTIFICATES. However, if the root certificate directory and file name differ from /etc/ssl/certs and ca-certificates.crt respectively, set the root certificate directory path using the HTTPS_ROOT_CERT_PATH ENV variable and the file name using the HTTPS_ROOT_CERT_FILE_NAME ENV variable.
If the HTTP client in the target application isn't configured to reload certificates with each API call, you must provide the CUSTOM_CERTIFICATES ENV variable to the chaos experiment and no need to set HTTPS_ROOT_CERT_PATH and HTTPS_ROOT_CERT_FILE_NAME ENV. The same custom certificates should be loaded into the target application. You can generate custom certificates using the following commands:
```
openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.crt -days 365 -nodes -subj '/CN=*'
cat key.pem cert.crt > ca-cert.pem
cat ca-cert.pem | base64 # provide it inside the CUSTOM_CERTIFICATES ENV
```
Load the cert.crt into the target application and provide the base64 encoded value of ca-cert.pem to the CUSTOM_CERTIFICATES ENV variable.

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

## enable https support
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-latency
      spec:
        components:
          env:
            # enable https support
            - name: HTTPS_ENABLED
              value: 'true'
            - name: CUSTOM_CERTIFICATES
              value: 'Y3VzdG9tIGNlcnRpZmljYXRlcwo='
            # provide the api path filter
            - name: PATH_FILTER
              value: '/status'
            # 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, either 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"

Use cases​

Prerequisites​

Mandatory tunables​

Optional tunables​

Target service port​

Response body​

Path Filter​

Destination ports​

HTTPS​

Ingress​

Egress​

Advanced fault tunables​

Container runtime and socket path​

Use cases

Prerequisites

Mandatory tunables

Optional tunables

Target service port

Response body

Path Filter

Destination ports

HTTPS

Ingress

Egress

Advanced fault tunables

Container runtime and socket path