---
title: Simulate Process Faults
---

This document describes how to use Chaosd to simulate process faults. The process faults use the Golang interface of the `kill` command to simulate the scenarios that the process is killed or stopped. You can create experiments either in the command-line mode or service mode.

## Create experiments using the command-line mode

Before creating an experiment, you can run the following command to see the process fault types that are supported by Chaosd:

```bash
chaosd attack process -h
```

The result is as follows:

```bash
Process attack related commands

Usage:
  chaosd attack process [command]

Available Commands:
  kill        kill process, default signal 9
  stop        stop process, this action will stop the process with SIGSTOP

Flags:
  -h, --help   help for process

Global Flags:
      --log-level string   the log level of chaosd, the value can be 'debug', 'info', 'warn' and 'error'

Use "chaosd attack process [command] --help" for more information about a command.
```

Currently, Chaosd supports simulating that a process is killed or stopped.

### Killing a process using the command-line mode

#### Commands for killing a process

```bash
chaosd attack process kill -h
```

The result is as follows:

```bash
kill process, default signal 9

Usage:
  chaosd attack process kill [flags]

Flags:
  -h, --help                 help for kill
  -p, --process string       The process name or the process ID
  -r, --recover-cmd string   The command to be run when recovering experiment
  -s, --signal int           The signal number to send (default 9)

Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --uid string         the experiment ID
```

#### Configuration description for killing a process

| Configuration item | Abbreviation | Description | Value |
| :-- | :-- | :-- | :-- |
| `process` | p | The name or the identifier of the process to be injected faults | string; the default value is `""`. |
| `recover-cmd` | r | The command to be run when recovering experiment | string; the default value is `""`. |
| `signal` | s | The provided value of the process signal | int; the default value is `9`. Currently, only `SIGKILL`, `SIGTERM`, and `SIGSTOP` are supported. |

#### Example for killing a process

```bash
chaosd attack process kill -p python
```

The result is as follows:

```bash
Attack process python successfully, uid: 10e633ac-0a37-41ba-8b4a-cd5ab92099f9
```

:::note

Only the experiments whose `signal` is `SIGSTOP` can be recovered.

:::

### Stopping a process using the command-line mode

#### Command for stopping a process

```bash
chaosd attack process stop -h
```

The result is as follows:

```bash
stop process, this action will stop the process with SIGSTOP

Usage:
  chaosd attack process stop [flags]

Flags:
  -h, --help             help for stop
  -p, --process string   The process name or the process ID

Global Flags:
      --log-level string   the log level of chaosd, the value can be 'debug', 'info', 'warn' and 'error'
```

#### Configuration description of stopping a process

| Configuration item | Abbreviation | Description | Value |
| :-- | :-- | :-- | :-- |
| `process` | p | The name or the identifier of the process to be stopped | string; the default value is `""`. |

#### Example for stopping a process

```bash
chaosd attack process stop -p python
```

The result is as follows:

```bash
Attack process python successfully, uid: 9cb6b3be-4f5b-4ecb-ae05-51050fcd0010
```

## Create experiments using the service mode

To create experiments using the service mode, follow the instructions below:

1. Run Chaosd in the service mode:

   ```bash
   chaosd server --port 31767
   ```

2. Send a `POST` HTTP request to the `/api/attack/process` path of the Chaosd service.

   ```bash
   curl -X POST 172.16.112.130:31767/api/attack/process -H "Content-Type:application/json" -d '{fault-configuration}'
   ```

   In the above command, you need to configure `fault-configuration` according to the fault types. For the corresponding parameters, refer to the parameters and examples of each fault type in the following sections.

:::note

When running an experiment, remember to record the UID of the experiment. When you want to end the experiment corresponding to the UID, you need to send a `DELETE` HTTP request to the `/api/attack/{uid}` path of the Chaosd service.

:::

### Simulate process faults using the service mode

#### Parameters for simulating process faults

| Parameter | Description                                                     | Value                              |
| :-------- | :-------------------------------------------------------------- | :--------------------------------- |
| `process` | The name or the identifier of the process to be injected faults | string; the default value is `""`. |
| `signal`  | The provided value of the process signal                        | int; the default value is `9`      |

#### Examples for simulating process faults using the service mode

##### Terminate a process

```bash
curl -X POST 172.16.112.130:31767/api/attack/process -H "Content-Type:application/json" -d '{"process":"12345","signal":15}'
```

The result is as follows:

```bash
{"status":200,"message":"attack successfully","uid":"c3c519bf-819a-4a7b-97fb-e3d0814481fa"}
```

##### Stop a process

```bash
curl -X POST 172.16.112.130:31767/api/attack/process -H "Content-Type:application/json" -d '{"process":"12345","signal":19}'
```

The result is as follows:

```bash
{"status":200,"message":"attack successfully","uid":"a00cca2b-eba7-4716-86b3-3e66f94880f7"}
```

:::note

Only the experiments whose `signal` is `SIGSTOP` can be recovered.

:::