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.

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.

Respond-related fields

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

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.