VMware HTTP modify response
VMware HTTP modify response injects HTTP chaos by modifying the status code, body or the headers, which affects the request (or response).
- Chaos is injected by starting the proxy server and redirecting the traffic through the proxy server.
- It tests the application's resilience to erroneous (or incorrect) HTTP response body.
- It modifies the headers of the requests and the responses of the service. This helps test the service's resilience towards incorrect or incomplete headers.
Usage
View the uses of the fault
Prerequisites
- Kubernetes >= 1.17
- Vcenter access to stop and start the VM.
- Kubernetes secret that has the Vcenter credentials in the
CHAOS_NAMESPACE
. Below is a sample secret file:
apiVersion: v1
kind: Secret
metadata:
name: vcenter-secret
namespace: litmus
type: Opaque
stringData:
VCENTERSERVER: XXXXXXXXXXX
VCENTERUSER: XXXXXXXXXXXXX
VCENTERPASS: XXXXXXXXXXXXX
Note
You can pass the VM credentials as secrets or as a ChaosEngine
environment variable.
Default validations
The VM should be in a healthy state.
Fault tunables
Fault tunables
Mandatory fields
Variables | Description | Notes |
---|---|---|
VM_NAME | Name of the VMware VM. | For example, test-vm . |
VM_USER_NAME | Username with sudo privileges. | For example, vm-user . |
VM_PASSWORD | User password. | For example, 1234 . |
TARGET_SERVICE_PORT | Service port to target. | Defaults to port 80. |
HTTP_CHAOS_TYPE | Type of the HTTP modify response chaos that is injected. | Defaults to 'status_code'. It accepts 'body', and 'header' as well. |
Status code modification related fields
STATUS_CODE | Modified the status code for the HTTP response. | If no value has been provided, a random value is selected from the list of supported values. Multiple values can be provided as comma-separated values, and a random value from the list is selected. Supported values include 200, 201, 202, 204, 300, 301, 302, 304, 307, 400, 401, 403, 404, 500, 501, 502, 503, 504. Defaults to a random status code. |
MODIFY_RESPONSE_BODY | Specify if the body should be modified according to the status code provided. | Defaults to true, wherein the body is replaced by a default template for the status code. |
Body modification related fields
RESPONSE_BODY | Body string used to overwrite the HTTP response body. | If no value has been provided, the response will be an empty body. Defaults to empty body. |
Header modification related fields
HEADERS_MAP | Map of the headers to modify (or add). | For example, {"X-Litmus-Test-Header":"X-Litmus-Test-Value"}. To remove a header, set the value to "". For example, {"X-Litmus-Test-Header": ""}. |
HEADER_MODE | Specify whether the response headers (or request headers) should be modified. | Defaults to response. Supports request as well. |
Optional fields
Variables | Description | Notes |
---|---|---|
TOTAL_CHAOS_DURATION | Duration that you specify, through which chaos is injected into the target resource (in seconds). | Defaults to 30s. |
CHAOS_INTERVAL | Time interval between two successive instance terminations (in seconds). | Defaults to 30s. |
SEQUENCE | Sequence of chaos execution for multiple instances. | Defaults to parallel. Supports serial sequence as well. |
RAMP_TIME | Period to wait before and after injecting chaos (in seconds). | For example, 30s. |
INSTALL_DEPENDENCY | Specify whether you wish to install the dependency to run the experiment. | Defaults to true. If the dependency already exists, you can turn it off. |
PROXY_PORT | Port where the proxy listens for requests. | Defaults to 20000. |
TOXICITY | Percentage of HTTP requests that are affected. | Defaults to 100. |
NETWORK_INTERFACE | Network interface used for the proxy. | Defaults to eth0. |
Fault examples
Common fault tunables
Refer to the common attributes to tune the common tunables for all the faults.
Target service port
It defines the port of the target service. You can tune it using the TARGET_SERVICE_PORT
environment variable.
Use the following example to tune it:
## provide the port of the targeted service
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
spec:
components:
env:
# provide the port of the targeted service
- name: TARGET_SERVICE_PORT
value: "80"
Modifying the response status code
You can use the below example to modify the status code of the response.
The HTTP_CHAOS_TYPE
environment variable is provided as the status_code
.
## provide the headers as a map
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
spec:
components:
env:
# HTTP response modification chaos type
- name: HTTP_CHAOS_TYPE
value: "status_code"
# modified status code for the http response
# if no value is provided, a random status code from the supported code list will selected
# if multiple comma separated values are provided, then a random value
# from the provided list will be selected
# if an invalid status code is provided, the fault will fail
# supported status code list:
# [200, 201, 202, 204, 300, 301, 302, 304, 307, 400, 401, 403, 404, 500, 501, 502, 503, 504]
- name: STATUS_CODE
value: '500'
# whether to modify the body as per the status code provided
- name: "MODIFY_RESPONSE_BODY"
value: "true"
# provide the port of the targeted service
- name: TARGET_SERVICE_PORT
value: "80"
Modifying the response headers
You can use the below example to modify the headers of the response.
The HTTP_CHAOS_TYPE
environment variable is provided as the header
.
## provide the headers as a map
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
spec:
components:
env:
# HTTP response modification chaos type
- name: HTTP_CHAOS_TYPE
value: "header"
# 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"}'
# 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"
Modifying the request headers
You can use the below example to modify the headers of the response.
The HTTP_CHAOS_TYPE
environment variable is provided as the header
.
## provide the headers as a map
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
spec:
components:
env:
# HTTP response modification chaos type
- name: HTTP_CHAOS_TYPE
value: "header"
# 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"}'
# 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"
Modifying the response body
You can use the below example to modify the body of the response.
The HTTP_CHAOS_TYPE
environment variable is provided as the body
.
## provide the headers as a map
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
spec:
components:
env:
# HTTP response modification chaos type
- name: HTTP_CHAOS_TYPE
value: "body"
# 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"
Proxy port
It defines the port where the proxy server listens for requests. You can tune it using the PROXY_PORT
environment variable.
Use the following example to tune it:
# provide the port for proxy server
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
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"
Toxicity
It defines the toxicity value added to the HTTP request. Toxicity value defines the percentage of the total number of HTTP requests that are affected. You can tune it using the TOXICITY
environment variable.
Use the following example to tune it:
## provide the toxicity
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
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
It defines the network interface used for the proxy. You can tune it using the NETWORK_INTERFACE
environment variable.
Use the following example to tune it:
## provide the network interface for proxy
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
chaosServiceAccount: litmus-admin
experiments:
- name: VMware-http-modify-response
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'