docs/en/latest/plugins/api-breaker.md

---
title: api-breaker
keywords:
  - Apache APISIX
  - API Gateway
  - API Breaker
description: This document describes the information about the Apache APISIX api-breaker Plugin, you can use it to protect Upstream services.
---

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## Description

The `api-breaker` Plugin implements circuit breaker functionality to protect Upstream services.

:::note

Whenever the Upstream service responds with a status code from the configured `unhealthy.http_statuses` list for the configured `unhealthy.failures` number of times, the Upstream service will be considered unhealthy.

The request is then retried in 2, 4, 8, 16 ... seconds until the `max_breaker_sec`.

In an unhealthy state, if the Upstream service responds with a status code from the configured list `healthy.http_statuses` for `healthy.successes` times, the service is considered healthy again.

:::

## Attributes

| Name                    | Type           | Required | Default | Valid values    | Description                                                                                                                                                                                                                                  |
|-------------------------|----------------|----------|---------|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| break_response_code     | integer        | True     |         | [200, ..., 599] | HTTP error code to return when Upstream is unhealthy.                                                                                                                                                                                        |
| break_response_body     | string         | False    |         |                 | Body of the response message to return when Upstream is unhealthy.                                                                                                                                                                           |
| break_response_headers  | array[object]  | False    |         | [{"key":"header_name","value":"can contain Nginx $var"}] | Headers of the response message to return when Upstream is unhealthy. Can only be configured when the `break_response_body` attribute is configured. The values can contain APISIX variables. For example, we can use `{"key":"X-Client-Addr","value":"$remote_addr:$remote_port"}`. |
| max_breaker_sec         | integer        | False    | 300     | >=3             | Maximum time in seconds for circuit breaking.                                                                                                                                                                                                |
| unhealthy.http_statuses | array[integer] | False    | [500]   | [500, ..., 599] | Status codes of Upstream to be considered unhealthy.                                                                                                                                                                                         |
| unhealthy.failures      | integer        | False    | 3       | >=1             | Number of failures within a certain period of time for the Upstream service to be considered unhealthy.                                                                                                                                                          |
| healthy.http_statuses   | array[integer] | False    | [200]   | [200, ..., 499] | Status codes of Upstream to be considered healthy.                                                                                                                                                                                           |
| healthy.successes       | integer        | False    | 3       | >=1             | Number of consecutive healthy requests for the Upstream service to be considered healthy.                                                                                                                                                    |

## Enable Plugin

The example below shows how you can configure the Plugin on a specific Route:

:::note
You can fetch the `admin_key` from `config.yaml` and save to an environment variable with the following command:

```bash
admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')
```

:::

```shell
curl "http://127.0.0.1:9180/apisix/admin/routes/1" \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "plugins": {
        "api-breaker": {
            "break_response_code": 502,
            "unhealthy": {
                "http_statuses": [500, 503],
                "failures": 3
            },
            "healthy": {
                "http_statuses": [200],
                "successes": 1
            }
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    },
    "uri": "/hello"
}'
```

In this configuration, a response code of `500` or `503` three times within a certain period of time triggers the unhealthy status of the Upstream service. A response code of `200` restores its healthy status.

## Example usage

Once you have configured the Plugin as shown above, you can test it out by sending a request.

```shell
curl -i -X POST "http://127.0.0.1:9080/hello"
```

If the Upstream service responds with an unhealthy response code, you will receive the configured response code (`break_response_code`).

```shell
HTTP/1.1 502 Bad Gateway
...
<html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>openresty</center>
</body>
</html>
```

## Delete Plugin

To remove the `api-breaker` Plugin, you can delete the corresponding JSON configuration from the Plugin configuration. APISIX will automatically reload and you do not have to restart for this to take effect.

```shell
curl http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "uri": "/hello",
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'
```