Skip to content

body-transformer.md

Latest commit

 

History

History
931 lines (785 loc) · 25 KB

body-transformer.md

File metadata and controls

931 lines (785 loc) · 25 KB
title body-transformer
keywords
Apache APISIX
API Gateway
Plugin
BODY TRANSFORMER
body-transformer
description The body-transformer Plugin performs template-based transformations to transform the request and/or response bodies from one format to another, for example, from JSON to JSON, JSON to HTML, or XML to YAML.

Description

The body-transformer Plugin performs template-based transformations to transform the request and/or response bodies from one format to another, for example, from JSON to JSON, JSON to HTML, or XML to YAML.

Attributes

Name Type Required Default Valid values Description
request object False Request body transformation configuration.
request.input_format string False [xml,json,encoded,args,plain,multipart] Request body original media type. If unspecified, the value would be determined by the Content-Type header to apply the corresponding decoder. The xml option corresponds to text/xml media type. The json option corresponds to application/json media type. The encoded option corresponds to application/x-www-form-urlencoded media type. The args option corresponds to GET requests. The plain option corresponds to text/plain media type. The multipart option corresponds to multipart/related media type. If the media type is neither type, the value would be left unset and the transformation template will be directly applied.
request.template string True Request body transformation template. The template uses lua-resty-template syntax. See the template syntax for more details. You can also use auxiliary functions _escape_json() and _escape_xml() to escape special characters such as double quotes, _body to access request body, and _ctx to access context variables.
request.template_is_base64 boolean False false Set to true if the template is base64 encoded.
response object False Response body transformation configuration.
response.input_format string False [xml,json,encoded,args,plain,multipart] Response body original media type. If unspecified, the decoder is determined by the Content-Type header where applicable: xml for text/xml, json for application/json, encoded for application/x-www-form-urlencoded, and multipart for any multipart/* content type. The args option reads URI query args from the request rather than decoding the response body. The plain option must be set explicitly and is not auto-detected from Content-Type: text/plain. If the media type is none of the supported types above, the value will be left unset and the transformation template will be directly applied.
response.template string True Response body transformation template.
response.template_is_base64 boolean False false Set to true if the template is base64 encoded.

Examples

The examples below demonstrate how you can configure body-transformer for different scenarios.

:::note

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

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

:::

The transformation template uses lua-resty-template syntax. See the template syntax to learn more.

You can also use auxiliary functions _escape_json() and _escape_xml() to escape special characters such as double quotes, _body to access request body, and _ctx to access context variables.

In all cases, you should ensure that the transformation template is a valid JSON string.

Transform between JSON and XML SOAP

The following example demonstrates how to transform the request body from JSON to XML and the response body from XML to JSON when working with a SOAP Upstream service.

Start the sample SOAP service:

cd /tmp
git clone https://github.com/spring-guides/gs-soap-service.git
cd gs-soap-service/complete
./mvnw spring-boot:run

Create the request and response transformation templates:

req_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1' | awk '{$1=$1};1' | tr -d '\r\n'
<?xml version="1.0"?>
<soap-env:Envelope xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/">
 <soap-env:Body>
  <ns0:getCountryRequest xmlns:ns0="http://spring.io/guides/gs-producing-web-service">
   <ns0:name>{{_escape_xml(name)}}</ns0:name>
  </ns0:getCountryRequest>
 </soap-env:Body>
</soap-env:Envelope>
EOF
)

rsp_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1' | awk '{$1=$1};1' | tr -d '\r\n'
{% if Envelope.Body.Fault == nil then %}
{
  "status":"{{_ctx.var.status}}",
  "currency":"{{Envelope.Body.getCountryResponse.country.currency}}",
  "population":{{Envelope.Body.getCountryResponse.country.population}},
  "capital":"{{Envelope.Body.getCountryResponse.country.capital}}",
  "name":"{{Envelope.Body.getCountryResponse.country.name}}"
}
{% else %}
{
  "message":{*_escape_json(Envelope.Body.Fault.faultstring[1])*},
  "code":"{{Envelope.Body.Fault.faultcode}}"
  {% if Envelope.Body.Fault.faultactor ~= nil then %}
  , "actor":"{{Envelope.Body.Fault.faultactor}}"
  {% end %}
}
{% end %}
EOF
)

awk and tr are used above to manipulate the template such that the template would be a valid JSON string.

Create a Route with body-transformer using the templates created previously. In the Plugin, set the request input format as JSON, the response input format as XML, and the Content-Type header to text/xml for the Upstream service to respond properly:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "methods": ["POST"],
    "uri": "/ws",
    "plugins": {
      "body-transformer": {
        "request": {
          "template": "'"$req_template"'",
          "input_format": "json"
        },
        "response": {
          "template": "'"$rsp_template"'",
          "input_format": "xml"
        }
      },
      "proxy-rewrite": {
        "headers": {
          "set": {
            "Content-Type": "text/xml"
          }
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "localhost:8080": 1
      }
    }
  }'

:::tip

If it is cumbersome to adjust complex text files to be valid transformation templates, you can use the base64 utility to encode the files, such as the following:

"body-transformer": {
  "request": {
    "template": "'"$(base64 -w0 /path/to/request_template_file)"'"
  },
  "response": {
    "template": "'"$(base64 -w0 /path/to/response_template_file)"'"
  }
}

:::

Send a request with a valid JSON body:

curl "http://127.0.0.1:9080/ws" -X POST -d '{"name": "Spain"}'

The JSON body sent in the request will be transformed into XML before being forwarded to the Upstream SOAP service, and the response body will be transformed back from XML to JSON.

You should see a response similar to the following:

{
  "status": "200",
  "currency": "EUR",
  "population": 46704314,
  "capital": "Madrid",
  "name": "Spain"
}

Modify Request Body

The following example demonstrates how to dynamically modify the request body.

Create a Route with body-transformer, in which the template appends the word world to the name and adds 10 to the age to set them as values to foo and bar respectively:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "template": "{\"foo\":\"{{name .. \" world\"}}\",\"bar\":{{age+10}}}"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a request to the Route:

curl "http://127.0.0.1:9080/anything" -X POST \
  -H "Content-Type: application/json" \
  -d '{"name":"hello","age":20}' \
  -i

You should see a response of the following:

{
  "args": {},
  "data": "{\"foo\":\"hello world\",\"bar\":30}",
  ...
  "json": {
    "bar": 30,
    "foo": "hello world"
  },
  "method": "POST",
  ...
}

Generate Request Body Using Variables

The following example demonstrates how to generate request body dynamically using the ctx context variables.

Create a Route with body-transformer, in which the template accesses the request argument using the Nginx variable arg_name:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "template": "{\"foo\":\"{{_ctx.var.arg_name .. \" world\"}}\"}"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a request to the Route with name argument:

curl -i "http://127.0.0.1:9080/anything?name=hello"

You should see a response like this:

{
  "args": {
    "name": "hello"
  },
  ...,
  "json": {
    "foo": "hello world"
  },
...
}

Transform Body from YAML to JSON

The following example demonstrates how to transform request body from YAML to JSON.

Create the request transformation template:

req_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1'
{%
    local yaml = require("tinyyaml")
    local body = yaml.parse(_body)
%}
{"foobar":"{{body.foobar.foo .. " " .. body.foobar.bar}}"}
EOF
)

Create a Route with body-transformer that uses the template:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "template": "'"$req_template"'"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a request to the Route with a YAML body:

body='
foobar:
  foo: hello
  bar: world'

curl "http://127.0.0.1:9080/anything" -X POST \
  -d "$body" \
  -H "Content-Type: text/yaml" \
  -i

You should see a response similar to the following, which verifies that the YAML body was appropriately transformed to JSON:

{
  "args": {},
  "data": "{\"foobar\":\"hello world\"}",
  ...
  "json": {
    "foobar": "hello world"
  },
...
}

Transform Form URL Encoded Body to JSON

The following example demonstrates how to transform form-urlencoded body to JSON.

Create a Route with body-transformer which sets the input_format to encoded and configures a template that appends string world to the name input, add 10 to the age input:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "input_format": "encoded",
          "template": "{\"foo\":\"{{name .. \" world\"}}\",\"bar\":{{age+10}}}"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a POST request to the Route with an encoded body:

curl "http://127.0.0.1:9080/anything" -X POST \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d 'name=hello&age=20'

You should see a response similar to the following:

{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "{\"foo\":\"hello world\",\"bar\":30}": ""
  },
  "headers": {
    ...
  },
  ...
}

Transform GET Request Query Parameter to Body

The following example demonstrates how to transform a GET request query parameter to request body. Note that this does not transform the HTTP method. To transform the method, see proxy-rewrite.

Create a Route with body-transformer, which sets the input_format to args and configures a template that adds a message to the request:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "input_format": "args",
          "template": "{\"message\": \"hello {{name}}\"}"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a GET request to the Route:

curl "http://127.0.0.1:9080/anything?name=john"

You should see a response similar to the following:

{
  "args": {},
  "data": "{\"message\": \"hello john\"}",
  "files": {},
  "form": {},
  "headers": {
    ...
  },
  "json": {
    "message": "hello john"
  },
  "method": "GET",
  ...
}

Transform Plain Media Type

The following example demonstrates how to transform requests with plain media type.

Create a Route with body-transformer, which sets the input_format to plain and configures a template to remove not and a subsequent space from the body string:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "input_format": "plain",
          "template": "{\"message\": \"{* string.gsub(_body, \"not \", \"\") *}\"}"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a POST request to the Route:

curl "http://127.0.0.1:9080/anything" -X POST \
  -d 'not actually json' \
  -i

You should see a response similar to the following:

{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "{\"message\": \"actually json\"}": ""
  },
  "headers": {
    ...
  },
  ...
}

Transform Multipart Media Type

The following example demonstrates how to transform requests with multipart media type.

Create a request transformation template which adds a status to the body based on the age provided in the request body:

req_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1'
{%
  local core = require 'apisix.core'
  local cjson = require 'cjson'

  if tonumber(context.age) > 18 then
      context._multipart:set_simple("status", "adult")
  else
      context._multipart:set_simple("status", "minor")
  end

  local body = context._multipart:tostring()
%}{* body *}
EOF
)

Create a Route with body-transformer, which sets the input_format to multipart and uses the previously created request template for transformation:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/anything",
    "plugins": {
      "body-transformer": {
        "request": {
          "input_format": "multipart",
          "template": "'"$req_template"'"
        }
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a multipart POST request to the Route:

curl -X POST \
  -F "name=john" \
  -F "age=10" \
  "http://127.0.0.1:9080/anything"

You should see a response similar to the following:

{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "age": "10",
    "name": "john",
    "status": "minor"
  },
  "headers": {
    "Accept": "*/*",
    "Content-Length": "361",
    "Content-Type": "multipart/form-data; boundary=------------------------qtPjk4c8ZjmGOXNKzhqnOP",
    ...
  },
  ...
}

Transform Response Body Based on Consumer Identity

The following example demonstrates how to customize response body transformations based on different Consumer identities. The example shows how to return different response formats to different Consumers while filtering sensitive fields and renaming properties.

Create the response transformation template that applies different transformations based on the Consumer identity:

rsp_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1' | awk '{$1=$1};1' | tr -d '\r\n'
{% local consumer_name = _ctx.consumer and _ctx.consumer.username or "" %}
{% if consumer_name == "consumer-a" then %}
{
  "user_id": {* user_id *},
  "display_name": {* _escape_json(username) *},
  "email": {* _escape_json(email) *}
}
{% elseif consumer_name == "consumer-b" then %}
{
  "user_id": {* user_id *},
  "email": {* _escape_json(email) *},
  "balance": {* balance *}
}
{% else %}
{* _body *}
{% end %}
EOF
)

Create three Consumers with key-auth configured:

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-a",
    "plugins": {
      "key-auth": {
        "key": "consumer-a"
      }
    }
  }'

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-b",
    "plugins": {
      "key-auth": {
        "key": "consumer-b"
      }
    }
  }'

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-c",
    "plugins": {
      "key-auth": {
        "key": "consumer-c"
      }
    }
  }'

Create a Route with body-transformer, key-auth, and mocking Plugins:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/mock",
    "plugins": {
      "key-auth": {},
      "mocking": {
        "response_example": "{\"user_id\":1001,\"username\":\"john_doe\",\"email\":\"john@example.com\",\"phone\":\"+1-555-0123\",\"balance\":1250.50}"
      },
      "body-transformer": {
        "response": {
          "input_format": "json",
          "template": "'"$rsp_template"'"
        }
      }
    }
  }'

Send requests with different apikey headers to verify the response transformations.

Send a request as consumer-a:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-a"

You should see a response similar to the following, which demonstrates these transformations:

  • The username field has been renamed to display_name
  • The sensitive phone and balance fields have been filtered out
{
  "user_id": 1001,
  "display_name": "john_doe",
  "email": "john@example.com"
}

Send a request as consumer-b:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-b"

You should see a response similar to the following, which demonstrates these transformations:

  • The username and phone fields have been filtered out
  • The balance field has been preserved
{
  "user_id": 1001,
  "email": "john@example.com",
  "balance": 1250.50
}

Send a request as consumer-c:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-c"

You should see a response similar to the following, which shows that the original response is returned unchanged:

{
  "user_id": 1001,
  "username": "john_doe",
  "email": "john@example.com",
  "phone": "+1-555-0123",
  "balance": 1250.50
}

Transform Nested Response Body Based on Consumer Identity

The following example demonstrates how to customize response body transformations based on different Consumer identities. The example shows how to extract nested fields, reorganize data structures, and flatten nested objects while providing different response formats to different Consumers based on their identity.

Create the response transformation template that extracts and reorganizes nested JSON fields based on the Consumer identity:

rsp_template=$(cat <<EOF | awk '{gsub(/"/,"\\\"");};1' | awk '{$1=$1};1' | tr -d '\r\n'
{% local consumer_name = _ctx.consumer and _ctx.consumer.username or "" %}
{% if consumer_name == "consumer-a" then %}
{
  "user_id": {* id *},
  "user_name": {* _escape_json(name) *},
  "email": {* _escape_json(profile.email) *},
  "location": {
    "city": {* _escape_json(profile.address.city) *},
    "country": {* _escape_json(profile.address.country) *}
  },
  "created_at": {* _escape_json(metadata.created_at) *}
}
{% elseif consumer_name == "consumer-b" then %}
{
  "id": {* id *},
  "name": {* _escape_json(name) *},
  "status": {* _escape_json(status) *},
  "profile": {
    "email": {* _escape_json(profile.email) *},
    "address": {
      "city": {* _escape_json(profile.address.city) *}
    }
  }
}
{% else %}
{* _body *}
{% end %}
EOF
)

Create Consumers with key-auth configured:

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-a",
    "plugins": {
      "key-auth": {
        "key": "consumer-a"
      }
    }
  }'

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-b",
    "plugins": {
      "key-auth": {
        "key": "consumer-b"
      }
    }
  }'

curl "http://127.0.0.1:9180/apisix/admin/consumers" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "username": "consumer-c",
    "plugins": {
      "key-auth": {
        "key": "consumer-c"
      }
    }
  }'

Create a Route with body-transformer, key-auth, and mocking Plugins using the nested structure template:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "body-transformer-route",
    "uri": "/mock",
    "plugins": {
      "key-auth": {},
      "mocking": {
        "response_example": "{\"id\":123,\"name\":\"John Doe\",\"status\":\"active\",\"profile\":{\"email\":\"john@example.com\",\"address\":{\"city\":\"New York\",\"country\":\"USA\"}},\"metadata\":{\"created_at\":\"2024-01-01\",\"tags\":[\"vip\",\"premium\"]}}"
      },
      "body-transformer": {
        "response": {
          "input_format": "json",
          "template": "'"$rsp_template"'"
        }
      }
    }
  }'

Send a request as consumer-a to verify the nested structure transformation:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-a"

You should see a response similar to the following, which demonstrates these nested field transformations:

  • profile.email has been extracted to top-level email
  • profile.address.city and profile.address.country have been combined into a new location object
  • metadata.created_at has been extracted to top-level created_at
{
  "user_id": 123,
  "user_name": "John Doe",
  "email": "john@example.com",
  "location": {
    "city": "New York",
    "country": "USA"
  },
  "created_at": "2024-01-01"
}

Send a request as consumer-b to verify the nested structure transformation:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-b"

You should see a response similar to the following, which demonstrates these transformations:

  • The original profile object structure has been preserved
  • profile.address.country and metadata fields have been filtered out
{
  "id": 123,
  "name": "John Doe",
  "status": "active",
  "profile": {
    "email": "john@example.com",
    "address": {
      "city": "New York"
    }
  }
}

Send a request as consumer-c to verify the nested structure transformation:

curl "http://127.0.0.1:9080/mock" -H "apikey: consumer-c"

You should see a response similar to the following, which shows that the original nested response is returned unchanged:

{
  "id": 123,
  "name": "John Doe",
  "status": "active",
  "profile": {
    "email": "john@example.com",
    "address": {
      "city": "New York",
      "country": "USA"
    }
  },
  "metadata": {
    "created_at": "2024-01-01",
    "tags": ["vip", "premium"]
  }
}