Pod HTTP modify body

Pod HTTP modify body is a Kubernetes pod-level chaos fault that injects chaos on the service whose port is provided using the TARGET_SERVICE_PORT environment variable. This is achieved by starting the proxy server and redirecting the traffic through the proxy server. This fault can be used to overwrite the HTTP response body by providing the new body value as RESPONSE_BODY.

Pod HTTP Modify Body

Use cases

Pod HTTP modify body tests the application's resilience to erroneous or incorrect HTTP response body.

Permissions required

Below is a sample Kubernetes role that defines the permissions required to execute the fault.

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: hce
  name: pod-http-modify-body
spec:
  definition:
    scope: Cluster # Supports "Namespaced" mode too
permissions:
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["create", "delete", "get", "list", "patch", "deletecollection", "update"]
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create", "get", "list", "patch", "update"]
  - apiGroups: [""]
    resources: ["pods/log"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["deployments, statefulsets"]
    verbs: ["get", "list"]
  - apiGroups: [""]
    resources: ["replicasets, daemonsets"]
    verbs: ["get", "list"]
  - apiGroups: [""]
    resources: ["chaosEngines", "chaosExperiments", "chaosResults"]
    verbs: ["create", "delete", "get", "list", "patch", "update"]
  - apiGroups: ["batch"]
    resources: ["jobs"]
    verbs: ["create", "delete", "get", "list", "deletecollection"]

Prerequisites

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

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
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

Optional tunables

Tunable	Description	Notes
CONTENT_ENCODING	Encoding type to compress or encode the response body.	Accepted values include gzip, deflate, br, identity. Defaults to none (no encoding). For more information, go to content encoding
CONTENT_TYPE	Content type of the response body.	Default: text or plain. For more information, go to content type
PROXY_PORT	Port where the proxy listens for requests.	Default: 20000. For more information, go to proxy port
NETWORK_INTERFACE	Network interface used for the proxy.	Default: `eth0`. For more information, go to network interface
TOXICITY	Percentage of HTTP requests to be affected.	Default: 100. For more information, go to toxicity
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-http-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: "2000"

Proxy port

Port on which the proxy server listens for requests. Tune it by using the PROXY_PORT environment variable.

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

## provide the port for proxy server
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-http-modify-body
      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"

Response body

String body that overwrites the HTTP 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-http-modify-body
      spec:
        components:
          env:
            # provide the body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "2000"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"

Toxicity

Percentage of the total number of HTTP requests to be affected. Tune it by using the TOXICITY environment variable.

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

## provide the toxicity
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-http-modify-body
      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"

Content encoding and content type

Content encoding and content type of the response body. Tune it by using the CONTENT_ENCODING and CONTENT_TYPE environment variables, respectively.

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

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-http-modify-body
      spec:
        components:
          env:
            # provide the encoding type for the response body
            # currently supported value are gzip, deflate
            # if empty no encoding will be applied
            - name: CONTENT_ENCODING
              value: "gzip"
            # provide the content type for the response body
            - name: CONTENT_TYPE
              value: "text/html"
            # provide the body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "2000"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"

Network interface

Network interface that is used for the proxy. Tune it by using the NETWORK_INTERFACE environment variable.

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

## provide the network interface for proxy
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-http-modify-body
      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"
            # provide the body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "2000"

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-http-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 body string to overwrite the response body
            - name: RESPONSE_BODY
              value: "2000"

Use cases​

Permissions required​

Prerequisites​

Mandatory tunables​

Optional tunables​

Target service port​

Proxy port​

Response body​

Toxicity​

Content encoding and content type​

Network interface​

Container runtime and socket path​

Use cases

Permissions required

Prerequisites

Mandatory tunables

Optional tunables

Target service port

Proxy port

Response body

Toxicity

Content encoding and content type

Network interface

Container runtime and socket path