Simulate HTTP faults

This document describes how to simulate HTTP faults by creating HTTPChaos experiments in Chaos Mesh.

HTTPChaos introduction

HTTPChaos is a fault type provided by Chaos Mesh. By creating HTTPChaos experiments, you can simulate the fault scenarios during the HTTP request and response processing. Currently, HTTPChaos supports simulating the following fault types:

• abort: interrupts the connection
• delay: injects latency into the request or response
• replace: replaces part of content in HTTP request or response messages
• patch: adds additional content to HTTP request or response messages

HTTPChaos supports combinations of different fault types. If you have configured multiple HTTP fault types at the same time when creating HTTPChaos experiments, the order set to inject the faults when the experiments start running is abort -> delay -> replace -> patch. When the abort fault cause short circuits, the connection will be directly interrupted.

For the detailed description of HTTPChaos configuration, see Field description below.

Notes

Before injecting the faults supported by HTTPChaos, note the followings:

• There is no control manager of Chaos Mesh running on the target Pod.
• The rules will affect both of clients and servers in the Pod, if you want to affect only one side, please refer to the specify side section.
• HTTPS accesses should be disabled, because injecting HTTPS connections is not supported currently.
• For HTTPChaos injection to take effect, the client should avoid reusing TCP socket. This is because HTTPChaos does not affect the HTTP requests that are sent via TCP socket before the fault injection.
• Use non-idempotent requests (such as most of the POST requests) with caution in production environments. If such requests are used, the target service may not return to normal status by repeating requests after the fault injection.

Create experiments using Chaos Dashboard

1. Open Chaos Dashboard, and click NEW EXPERIMENT on the page to create a new experiment:

   

2. In the Choose a Target area, choose HTTP FAULT and select a specific behavior, such as RESPONSE ABORT. Then fill out specific configurations.

   

3. Submit the experiment.

   In the example above, you have configured injecting the "Response abort" fault into all requests of Port 80.

Create experiments using YAML files

Chaos Mesh also supports using YAML configuration files to create HTTPChaos experiments. In a YAML file, you can simulate either one HTTP fault type or a combination of different HTTP fault types.

Example of abort

1. Write the experimental configuration to the http-abort-failure.yaml file as the example below:

   apiVersion: chaos-mesh.org/v1alpha1
   kind: HTTPChaos
   metadata:
     name: test-http-chaos
   spec:
     mode: all
     selector:
       labelSelectors:
         app: nginx
     target: Request
     port: 80
     method: GET
     path: /api
     abort: true
     duration: 5m

   Based on this configuration example, Chaos Mesh will inject the abort fault into the specified pod for 5 minutes. During the fault injection, the GET requests sent through port 80 in the /api path of the target Pod will be interrupted.

2. After the configuration file is prepared, use kubectl to create the experiment:

   kubectl apply -f ./http-abort-failure.yaml

Example of fault combinations

1. Write the experimental configuration to http-failure.yaml file as the example below:

   apiVersion: chaos-mesh.org/v1alpha1
   kind: HTTPChaos
   metadata:
     name: test-http-chaos
   spec:
     mode: all
     selector:
       labelSelectors:
         app: nginx
     target: Request
     port: 80
     method: GET
     path: /api/*
     delay: 10s
     replace:
       path: /api/v2/
       method: DELETE
     patch:
       headers:
         - ['Token', '<one token>']
         - ['Token', '<another token>']
       body:
         type: JSON
         value: '{"foo": "bar"}'
     duration: 5m

   Based on this configuration example, Chaos Mesh will inject the delay fault, replace fault, and patch fault consecutively.

2. After the configuration file is prepared, use kubectl to create the experiment:

   kubectl apply -f ./http-failure.yaml

Field description

Description for common fields

Common fields are meaningful when the target of fault injection is Request or Response.

Parameter	Type	Description	Default value	Required	Example
mode	string	Specifies the mode of the experiment. The mode options include one (selecting a random pod), all (selecting all eligible pods), fixed (selecting a specified number of eligible pods), fixed-percent (selecting a specified percentage of Pods from the eligible pods), and random-max-percent (selecting the maximum percentage of Pods from the eligible pods).		yes	one
value	string	Provides parameters for the mode configuration depending on the value of mode.		no	1
target	string	Specifies whether the target of fault injuection is Request or Response. The target-related fields should be configured at the same time.		yes	Request
port	int32	The TCP port that the target service listens on.		yes	80
path	string	The URI path of the target request. Supports Matching wildcards.	Takes effect on all paths by default.	no	/api/*
method	string	The HTTP method of the target request method.	Takes effect for all methods by default.	no	GET
request_headers	map[string]string	Matches request headers to the target service.	Takes effect for all requests by default.	no	Content-Type: application/json
abort	bool	Indicates whether to inject the fault that interrupts the connection.	false	no	true
delay	string	Specifies the time for a latency fault.	0	no	10s
replace.headers	map[string]string	Specifies the key pair used to replace the request headers or response headers.		no	Content-Type: application/xml
replace.body	[]byte	Specifies request body or response body to replace the fault (Base64 encoded).		no	eyJmb28iOiAiYmFyIn0K
patch.headers	[][]string	Specifies the attached key pair of the request headers or response headers with patch faults.		no	- [Set-Cookie, one cookie]
patch.body.type	string	Specifies the type of patch faults of the request body or response body. Currently, it only supports JSON.		no	JSON
patch.body.value	string	Specifies the fault of the request body or response body with patch faults.		no	"{"foo": "bar"}"
duration	string	Specifies the duration of a specific experiment.		yes	30s
scheduler	string	Specifies the scheduling rules for the time of a specific experiment.		no	5 * * * *

note

• When creating experiments with YAML files, replace.body must be the base64 encoding of the replacement content.

• When creating experiments with the Kubernetes API, there is no need to encode the replacement content, just convert it to []byte and put it into the httpchaos.Spec.Replace.Body field. The following is an example:

httpchaos.Spec.Replace.Body = []byte(`{"foo": "bar"}`)

Description for target-related fields

Request-related fields

The Request field is a meaningful when the target set to Request during the fault injection.

Parameter	Type	Description	Default value	Required	Example
replace.path	string	Specifies the URI path used to replace content.		no	/api/v2/
replace.method	string	Specifies the replaced content of the HTTP request method.		no	DELETE
replace.queries	map[string]string	Specifies the replaced key pair of the URI query.		no	foo: bar
patch.queries	[][]string	Specifies the attached key pair of the URI query with patch faults.		no	- [foo, bar]

Respond-related fields

The Response is a meaningful when the target set to Response during the fault injection.

Parameter	Type	Description	Default value	Required	Example
code	int32	Specifies the status code responded by target.	Takes effect for all status codes by default.	no	200
response_headers	map[string]string	Matches request headers to target.	Takes effect for all responses by default.	no	Content-Type: application/json
replace.code	int32	Specifies the replaced content of the response status code.		no	404

Specify side

The rules will affect both of clients and servers in the Pod by default, but you can affect only one side by selecting the request headers.

This section provides some examples to specify the affected side, you can adjust the header selector in rules depend on your particular cases.

Client side

To inject faults into clients in the Pod without affecting servers, you can select the request/response by the Host header in the request.

For example, if you want to interrupt all requests to http://example.com/, you can apply the following YAML config:

apiVersion: chaos-mesh.org/v1alpha1
kind: HTTPChaos
metadata:
  name: test-http-client
spec:
  mode: all
  selector:
    labelSelectors:
      app: some-http-client
  target: Request
  port: 80
  path: '*'
  request_headers:
    Host: 'example.com'
  abort: true

Server side

To inject faults into servers in the Pod without affecting clients, you can also select the request/response by the Host header in the request.

For example, if you want to interrupt all requests to your server behind service nginx.nginx.svc, you can apply the following YAML config:

apiVersion: chaos-mesh.org/v1alpha1
kind: HTTPChaos
metadata:
  name: test-http-server
spec:
  mode: all
  selector:
    labelSelectors:
      app: nginx
  target: Request
  port: 80
  path: '*'
  request_headers:
    Host: 'nginx.nginx.svc'
  abort: true

In other cases, especially when injecting the inbound request from outside, you may select the request/response by the X-Forwarded-Host header in the request.

For example, if you want to interrupt all requests to your server behind a public gateway nginx.host.org, you can apply the following YAML config:

apiVersion: chaos-mesh.org/v1alpha1
kind: HTTPChaos
metadata:
  name: test-http-server
spec:
  mode: all
  selector:
    labelSelectors:
      app: nginx
  target: Request
  port: 80
  path: '*'
  request_headers:
    X-Forwarded-Host: 'nginx.host.org'
  abort: true

Local debugging

If you are not sure of the effects of certain fault injections, you can also test the corresponding features locally using rs-tproxy. Chaos Mesh also provides HTTPChaos by using rs-tproxy.