response-rewrite

Description

The response-rewrite Plugin rewrites the content returned by the Upstream and APISIX.

This Plugin can be useful in these scenarios:

• To set Access-Control-Allow-* field for supporting CORS.
• To set custom status_code and Location fields in the header to redirect.

tip

You can also use the redirect Plugin to setup redirects.

Attributes

Name	Type	Required	Default	Valid values	Description
status_code	integer	False		[200, 598]	New HTTP status code in the response. If unset, falls back to the original status code.
body	string	False			New body of the response. The content-length would also be reset.
body_base64	boolean	False	false		When set, the body of the request will be decoded before writing to the client.
headers	object	False			New headers for the response. Headers are overwritten if they are present in the Upstream response otherwise, they are added to the Upstream headers. To remove a header, set the header value to an empty string. The values in the header can contain Nginx variables like $remote_addr and $balancer_ip.
vars	array[]	False		See lua-resty-expr for a list of available operators.	Nginx variable expressions to conditionally execute the rewrite. The Plugin will be executed unconditionally if this value is empty.
filters	array[]	False			List of filters that modify the response body by replacing one specified string with another.
filters.regex	string	True			Regex pattern to match on the response body.
filters.scope	string	False	"once"	"once","global"	Range to substitute. once substitutes the first match of filters.regex and global does global substitution.
filters.replace	string	True			Content to substitute with.
filters.options	string	False	"jo"		Regex options. See ngx.re.match.

note

Only one of body or filters can be configured.

Enabling the Plugin

The example below enables the response-rewrite Plugin on a specific Route:

curl http://127.0.0.1:9080/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "methods": ["GET"],
    "uri": "/test/index.html",
    "plugins": {
        "response-rewrite": {
            "body": "{\"code\":\"ok\",\"message\":\"new json body\"}",
            "headers": {
                "X-Server-id": 3,
                "X-Server-status": "on",
                "X-Server-balancer_addr": "$balancer_ip:$balancer_port"
            },
            "vars":[
                [ "status","==",200 ]
            ]
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:80": 1
        }
    }
}'

Here, vars is configured to run the Plugin only on responses with a 200 status code.

Example usage

Once you have enabled the Plugin as shown above, you can make a request:

curl -X GET -i  http://127.0.0.1:9080/test/index.html

The response will be as shown below no matter what the response is from the Upstream:

HTTP/1.1 200 OK
Date: Sat, 16 Nov 2019 09:15:12 GMT
Transfer-Encoding: chunked
Connection: keep-alive
X-Server-id: 3
X-Server-status: on
X-Server-balancer_addr: 127.0.0.1:80

{"code":"ok","message":"new json body"}

IMPORTANT

ngx.exit will interrupt the execution of a request and returns its status code to Nginx.

However, if ngx.exit is executed during an access phase, it will only interrupt the request processing phase and the response phase will still continue to run.

So, if you have configured the response-rewrite Plugin, it do a force overwrite of the response.

Phase	rewrite	access	header_filter	body_filter
rewrite	ngx.exit	√	√	√
access	×	ngx.exit	√	√
header_filter	√	√	ngx.exit	√
body_filter	√	√	×	ngx.exit

The example below shows how you can replace a key in the response body. Here, the key X-Amzn-Trace-Id is replaced with X-Amzn-Trace-Id-Replace by configuring the filters attribute using regex:

curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
  "plugins":{
    "response-rewrite":{
      "headers":{
        "X-Server-id":3,
        "X-Server-status":"on",
        "X-Server-balancer_addr":"$balancer_ip:$balancer_port"
      },
      "filters":[
        {
          "regex":"X-Amzn-Trace-Id",
          "scope":"global",
          "replace":"X-Amzn-Trace-Id-Replace"
        }
      ],
      "vars":[
        [
          "status",
          "==",
          200
        ]
      ]
    }
  },
  "upstream":{
    "type":"roundrobin",
    "scheme":"https",
    "nodes":{
      "httpbin.org:443":1
    }
  },
  "uri":"/*"
}'

curl -X GET -i  http://127.0.0.1:9080/get

HTTP/1.1 200 OK
Transfer-Encoding: chunked
X-Server-status: on
X-Server-balancer-addr: 34.206.80.189:443
X-Server-id: 3

{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Host": "127.0.0.1",
    "User-Agent": "curl/7.29.0",
    "X-Amzn-Trace-Id-Replace": "Root=1-629e0b89-1e274fdd7c23ca6e64145aa2",
    "X-Forwarded-Host": "127.0.0.1"
  },
  "origin": "127.0.0.1, 117.136.46.203",
  "url": "https://127.0.0.1/get"
}

Disable Plugin

To disable the response-rewrite 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.

curl http://127.0.0.1:9080/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "methods": ["GET"],
    "uri": "/test/index.html",
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:80": 1
        }
    }
}'