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Pod API status code

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.

Pod API Status Code

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.

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-api-status-code
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_CONTAINER Name of the container subject to changes in the API status code. None. For more information, go to target specific container
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.
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 .

Optional tunables​

Tunable Description Notes
PATH_FILTER API path or route used for the filtering. Targets all paths if not provided. For more information, go to path filter .
HEADERS_FILTERS Filters for HTTP request headers accept multiple comma-separated headers in the format key1:value1,key2:value2. For more information, go to header filters.
METHODS The HTTP request method type accepts comma-separated HTTP methods in upper cases, such as "GET,POST". For more information, go to methods.
QUERY_PARAMS HTTP request query parameter filters accept multiple comma-separated query parameters in the format of param1:value1,param2:value2. For more information, go to query params.
SOURCE_HOSTS Includes comma-separated source host names as filters, indicating the origin of the HTTP request. This is specifically relevant to the "ingress" type. For more information, go to source hosts.
SOURCE_IPS This includes comma-separated source IPs as filters, indicating the origin of the HTTP request. This is specifically relevant to the "ingress" type. For more information, go to source ips.
DESTINATION_HOSTS Comma-separated destination host names are used as filters, indicating the hosts on which you call the API. This specification applies exclusively to the "egress" type. For more information, go to destination hosts.
DESTINATION_IPS Comma-separated destination IPs are used as filters, indicating the hosts on which you call the API. This specification applies exclusively to the "egress" type. For more information, go to destination hosts.
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.
LIB_IMAGE Image used to inject chaos. Default: harness/chaos-go-runner:main-latest. For more information, go to image used by the helper pod.
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 .
DESTINATION_PORTS comma-separated list of the destination service or host ports for which egress traffic should be affected Default: 80,443. 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
CA_CERTIFICATES Provide the CA certificates for the proxy server to serve as intermediate certificates for HTTPS communication. HTTPS communication necessitates its use as intermediate certificates by the proxy server. These certificates should be loaded into the target application. For more information, go to HTTPS
SERVER_CERTIFICATES Provide the Server certificates for the proxy server to serve as intermediate certificates for HTTPS communication. HTTPS communication necessitates its use as intermediate certificates by the proxy server. The corresponding CA certificates should be loaded as root certificates inside 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 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 (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-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"

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-status-code
      spec:
        components:
          env:
            # provide destination ports
            - name: DESTINATION_PORTS
              value: '80,443'
            # 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"

HTTPS​

To enable HTTPS support for both incoming and outgoing traffic, set the HTTPS_ENABLED field to true. The configuration details vary depending on whether it's applied to ingress or egress traffic.

Ingress​

Set the HTTPS_ENABLED parameter if the target application's HTTPS URL includes a port (e.g., https://<hostname>:port). If the URL is in the format https://<hostname> without a port, this setting is not required.

Egress​

For outgoing traffic, enable HTTPS support by setting HTTPS_ENABLED to true. This ensures TLS certificates are used for secure communication through 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 CA_CERTIFICATES or SERVER_CERTIFICATES. However, if the root certificate directory or file name differs from /etc/ssl/certs and ca-certificates.crt, specify them using the HTTPS_ROOT_CERT_PATH and HTTPS_ROOT_CERT_FILE_NAME environment variables.

  • If the HTTP client doesn't reload certificates with every API call, provide either the CA_CERTIFICATES or SERVER_CERTIFICATES environment variables to the chaos experiment. In this case, you don’t need to set HTTPS_ROOT_CERT_PATH and HTTPS_ROOT_CERT_FILE_NAME. The relevant CA certificates must be provided to the target application.

    Generate Certificates​

    You can set either CA_CERTIFICATES or SERVER_CERTIFICATES depending on the use case.

    1. Self-Signed Certificates: To generate self-signed certificates, use the following commands:

      openssl req -x509 -newkey rsa:4096 -keyout ca.key -out ca.crt -days 365 -nodes -subj '/CN=*'
      cat ca.key ca.crt > ca-cert.pem
      cat ca-cert.pem | base64 # provide this value in the CA_CERTIFICATES environment variable

      Load the ca.crt CA certificate as the root CA into the target application, and set the base64-encoded value of ca-cert.pem in the CA_CERTIFICATES environment variable inside the experiment manifest.

    2. CA-Signed Certificates: If you're using a trusted Certificate Authority (CA) to sign the server certificates, loading CA certificates into the target application may not be necessary, as it might already have the required CA certificates. Instead, you can simply set the SERVER_CERTIFICATES environment variable with the server certificates, as shown below:

      cat server.key server.crt > server-cert.pem
      cat server-cert.pem | base64 # provide this value in the SERVER_CERTIFICATES environment 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-status-code
      spec:
        components:
          env:
            # enable https support
            - name: HTTPS_ENABLED
              value: 'true'
            - name: SERVER_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.
  • 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'

Advanced filters​

  • HEADERS_FILTERS: The HTTP request headers filters, that accept multiple comma-separated headers in the format of key1:value1,key2:value2.
  • METHODS: The HTTP request method type filters, that accept comma-separated HTTP methods in upper case, that is, GET,POST.
  • QUERY_PARAMS: The HTTP request query parameters filter, accepts multiple comma-separated query parameters in the format of param1:value1,param2:value2.
  • SOURCE_HOSTS: Comma-separated source host names filters, indicating the origin of the HTTP request. This is relevant to the ingress type, specified by SERVICE_DIRECTION environment variable.
  • SOURCE_IPS: Comma-separated source IPs filters, indicating the origin of the HTTP request. This is specifically relevant to the ingress type, specified by SERVICE_DIRECTION environment variable.
  • DESTINATION_HOSTS: Comma-separated destination host names filters, indicating the hosts on which you call the API. This specification applies exclusively to the egress type, specified by SERVICE_DIRECTION environment variable.
  • DESTINATION_IPS: Comma-separated destination IPs filters, indicating the hosts on which you call the API. This specification applies exclusively to the egress type, specified by SERVICE_DIRECTION environment variable.

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

# it injects the api status code 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 headers filters
            - name: HEADERS_FILTERS
              value: 'key1:value1,key2:value2'
            # provide the methods filters
            - name: METHODS
              value: 'GET,POST'
            # provide the query params filters
            - name: QUERY_PARAMS
              value: 'param1:value1,param2:value2'
            # provide the source hosts filters
            - name: SOURCE_HOSTS
              value: 'host1,host2'
            # provide the source ips filters
            - name: SOURCE_IPS
              value: 'ip1,ip2'
            # provide the connection type
            - name: SERVICE_DIRECTION
              value: 'ingress'
            # provide the port of the targeted service
            - name: TARGET_SERVICE_PORT
              value: "80"
            - name: STATUS_CODE
              value: "500"

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"