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Pod HTTP modify header

Pod HTTP modify header 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 done by starting the proxy server and redirecting the traffic through the proxy server. This fault modifies headers of the requests and responses of the service.

Pod HTTP Modify Header

Use cases​

Pod HTTP modify header can be used to test resilience towards incorrect or incomplete headers in application services.

Prerequisites​

  • Kubernetes > 1.16
  • 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 service to target. Default: 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.
HEADERS_MAP Map of the headers to modify or add. For example, {"X-Litmus-Test-Header": "X-Litmus-Test-Value"}. To remove a header, just set the value to ""; For example, {"X-Litmus-Test-Header": ""}.For more information, go to headers map
HEADER_MODE Specifies whether to modify the response headers or request headers. Accepted values are 'request' and 'response'. Default: response. For more information, go to header mode

Optional tunables​

Tunable Description Notes
PROXY_PORT Port where the proxy listen 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. Supports 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 to inject chaos (in seconds). Default: 60 s. For more information, go to duration of the chaos
TARGET_PODS Comma-separated list of the application pod names subject to pod HTTP modify header. 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-chaos
      spec:
        components:
          env:
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            # map of headers to modify/add
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'

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-chaos
      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"
            # map of headers to modify/add
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'

Headers map​

Map of the headers that need to be modified or added to the HTTP request or response. Tune it by using the HEADERS_MAP environment variable.

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

## provide the headers as a map
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-chaos
      spec:
        components:
          env:
            # map of headers to modify/add; Eg: {"X-Litmus-Test-Header": "X-Litmus-Test-Value"}
            # to remove a header, just set the value to ""; Eg: {"X-Litmus-Test-Header": ""}
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"

Header mode​

Specifies whether or not the request or the response header has to be modified. Tune it by using the HEADER_MODE environment variable.

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

## provide the mode of the header modification; request/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-http-chaos
      spec:
        components:
          env:
            # whether to modify response headers or request headers. Accepted values: request, response
            - name: HEADER_MODE
              value: "response"
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            # map of headers to modify/add
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'

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-header
      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"

Network interface​

Network interface 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 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-chaos
      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"
            # map of headers to modify/add
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'

Container runtime and socket path​

The CONTAINER_RUNTIME and SOCKET_PATH environment variables 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-chaos
      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"
            # map of headers to modify/add
            - name: HEADERS_MAP
              value: '{"X-Litmus-Test-Header": "X-Litmus-Test-Value"}'