feat(request-transformer) change HTTP method of upstream request (#1635)

kong/plugins/request-transformer/access.lua

@@ -10,6 +10,7 @@ local req_read_body = ngx.req.read_body
 local req_set_body_data = ngx.req.set_body_data
 local req_get_body_data = ngx.req.get_body_data
 local req_clear_header = ngx.req.clear_header
+local req_set_method = ngx.req.set_method
 local encode_args = ngx.encode_args
 local ngx_decode_args = ngx.decode_args
 local type = type
@@ -303,7 +304,33 @@ local function transform_body(conf)
   end
 end
 
+local function transform_method(conf)
+  if conf.http_method then
+    req_set_method(ngx["HTTP_"..conf.http_method:upper()])
+    if conf.http_method == "GET" or conf.http_method == "HEAD" or conf.http_method == "TRACE" then
+      local content_type_value = req_get_headers()[CONTENT_TYPE]
+      local content_type = get_content_type(content_type_value)
+      if content_type == ENCODED then
+        -- Also put the body into querystring
+
+        -- Read the body
+        req_read_body()
+        local body = req_get_body_data()
+        local parameters = decode_args(body)
+
+        -- Append to querystring
+        local querystring = req_get_uri_args()
+        for name, value in pairs(parameters) do
+          querystring[name] = value
+        end
+        req_set_uri_args(querystring)
+      end
+    end
+  end
+end
+
 function _M.execute(conf)
+  transform_method(conf)
   transform_body(conf)
   transform_headers(conf)
   transform_querystrings(conf)

kong/plugins/request-transformer/schema.lua

@@ -10,8 +10,19 @@ local function check_for_value(value)
   return true
 end
 
+local function check_method(value)
+  if not value then return true end
+  local method = value:upper()
+  local ngx_method = ngx["HTTP_"..method]
+  if not ngx_method then
+    return false, method.." is not supported"
+  end
+  return true
+end
+
 return {
   fields = {
+    http_method = {type = "string", func = check_method},
     remove = {
       type = "table",
       schema = {

spec/03-plugins/13-request-transformer/01-schema_spec.lua

@@ -0,0 +1,16 @@
+local schemas = require "kong.dao.schemas_validation"
+local request_transformer_schema = require "kong.plugins.request-transformer.schema"
+local validate_entity = schemas.validate_entity
+
+describe("Plugin: request-transformer (schema)", function()
+  it("validates http_method", function()
+    local ok, err = validate_entity({http_method = "GET"}, request_transformer_schema)
+    assert.is_nil(err)
+    assert.True(ok)
+  end)
+  it("errors invalid http_method", function()
+    local ok, err = validate_entity({http_method = "HELLO"}, request_transformer_schema)
+    assert.equal("HELLO is not supported", err.http_method)
+    assert.False(ok)
+  end)
+end)

spec/03-plugins/13-request-transformer/01-access_spec.lua → spec/03-plugins/13-request-transformer/02-access_spec.lua

@@ -12,6 +12,8 @@ describe("Plugin: request-transformer (access)", function()
     local api4 = assert(helpers.dao.apis:insert {request_host = "test4.com", upstream_url = "http://mockbin.com"})
     local api5 = assert(helpers.dao.apis:insert {request_host = "test5.com", upstream_url = "http://mockbin.com"})
     local api6 = assert(helpers.dao.apis:insert {request_host = "test6.com", upstream_url = "http://mockbin.com"})
+    local api7 = assert(helpers.dao.apis:insert {request_host = "test7.com", upstream_url = "http://mockbin.com"})
+    local api8 = assert(helpers.dao.apis:insert {request_host = "test8.com", upstream_url = "http://mockbin.com"})
 
     assert(helpers.dao.plugins:insert {
       api_id = api1.id,
@@ -89,6 +91,20 @@ describe("Plugin: request-transformer (access)", function()
         }
       }
     })
+    assert(helpers.dao.plugins:insert {
+      api_id = api7.id,
+      name = "request-transformer",
+      config = {
+        http_method = "POST"
+      }
+    })
+    assert(helpers.dao.plugins:insert {
+      api_id = api8.id,
+      name = "request-transformer",
+      config = {
+        http_method = "GET"
+      }
+    })
   end)
   teardown(function()
     helpers.stop_kong()
@@ -101,6 +117,41 @@ describe("Plugin: request-transformer (access)", function()
     if client then client:close() end
   end)
 
+  describe("http method", function()
+    it("changes the HTTP method from GET to POST", function()
+      local r = assert(client:send {
+        method = "GET",
+        path = "/request?hello=world&name=marco",
+        headers = {
+          host = "test7.com"
+        }
+      })
+      assert.response(r).has.status(200)
+      local json = assert.response(r).has.jsonbody()
+      assert.equal("POST", json.method)
+      assert.equal("world", json.queryString.hello)
+      assert.equal("marco", json.queryString.name)
+    end)
+    it("changes the HTTP method from POST to GET", function()
+      local r = assert(client:send {
+        method = "POST",
+        path = "/request?hello=world",
+        body = {
+          name = "marco"
+        },
+        headers = {
+          ["Content-Type"] = "application/x-www-form-urlencoded",
+          host = "test8.com"
+        }
+      })
+      assert.response(r).has.status(200)
+      local json = assert.response(r).has.jsonbody()
+      assert.equal("GET", json.method)
+      assert.equal("marco", json.postData.params.name)
+      assert.equal("world", json.queryString.hello)
+      assert.equal("marco", json.queryString.name)
+    end)
+  end)
   describe("remove", function()
     it("specified header", function()
       local r = assert(client:send {