svenwal/kong-plugin-search-and-replace

A Kong plugin which replaces contents in the body of the request and response

About

search-and-replace is a Kong plugin which replaces in the requst and response any string with another string.

Configuration parameters

FORM PARAMETER	DEFAULT	DESCRIPTION
config.request_search_string		The search string to be found in the payload (see also notes on search string in known limitations)
config.request_replace_string		The replacement for the above string
config.request_maximum_payload_size		Maximum payload size in bytes being processed - note also: Kong wide maximum is set with parameter client_body_buffer_size
config.request_maximum_payload_no_content_length_forward_unprocessed	false	Should the request handled if no content-length header is sent. Will return a 413 if set to false
config.request_maximum_payload_exceeded_forward_unprocessed	true	Shall the unaltered body be forwarded if payload size is exceeded. Note: if you are using this plugin to hide sensitive data make sure to set this to false as otherwise the unprocessed data gets forwarded. Will return a 411 if set to false
config.response_search_string		The search string to be found in the payload (see also notes on search string in known limitations)
config.response_replace_string		The replacement for the above string
config.response_maximum_payload_size		Maximum payload size in bytes being processed - note also: Kong wide maximum is set with parameter client_body_buffer_size
config.response_maximum_payload_no_content_length_forward_unprocessed	false	Should the request handled if no content-length header is sent. Will return a 500 if set to false
config.response_maximum_payload_exceeded_forward_unprocessed	false	Shall the unaltered body be forwarded if payload size is exceeded. Note: if you are using this plugin to hide sensitive data make sure to set this to false as otherwise the unprocessed data gets forwarded. Will return a 500 if set to false

Known limitations

• TBD: GZip encoded payloads are not support
• TBD: The search string is a Lua pattern matching string so be careful and quote special characters ( ) % . + - * [ ? ^ $ with a prefixed % (see also https://riptutorial.com/lua/example/20315/lua-pattern-matching). Will add an option to automatically quote them if regexp is not wanted in a later release
• TBD: only one replacement is done per request/response. This will be extended by providing arrays for search and replace config paramters instead
• The response will not provide a content-length header anymore due to the plugin phases within Kong

Examples

Before enabling plugin:

> http :8000/searchAndReplace

HTTP/1.1 200 OK
(...)

Foo

https://www.google.de

bar

Response before enabling the plugin

Note the quoted . in the url!

> http -f :8001/services/<SERVICE>/plugins name=search-and-replace config.response_search_string = "https://www%.google%.de" config.response_replace_string = "https://duckduckgo.com"

HTTP/1.1 201 Created
(...)

{
    "config": {
        "response_search_string": "https://www%.google%.de",
        "response_replace_string": "https://duckduckgo.com",
    },
    "created_at": 1554887400000,
    "enabled": true,
    "id": "1a659088-2e38-4a9f-bfef-f84400c86f5a",
    "name": "search-and-replace",
    "service_id": "f42acc5b-4e85-4ec2-8638-c7dbdd84b8a9"
}

Response after enabling plugin

> http :8000/searchAndReplace

HTTP/1.1 200 OK
(...)

Foo

https://duckduckgo.com

bar