apisix~自定义文件上传代理插件~支持form-data文件和kv参数
参考文献
- https://stackoverflow.com/questions/24535189/composing-multipart-form-data-with-a-different-content-type-on-each-parts-with-j
- https://www.reddit.com/r/lua/comments/yaizxv/lua_post_multipartformdata_and_a_file_via/?rdt=60519
- https://github.com/rstudio/redx/issues/19
问题产生的原因
后端有个文件上传服务,前端可以直接像文件上传到服务器,但这个上传服务除了有form-data文件流之外,还需要有其它key/value的表单参数,这些参数是固定的,或者有一定的规则,这时我们通过apisix代理一下,就显得更加灵活和理了。
http中的multipart/form-data消息体如下
修改后的请求,是一个标准的http请求,你通过postman的codesnippet视图也可以看到,代码如下
POST /mobile-server/manager/6.0.0.0.0/cdnManage/customUpload HTTP/1.1
Host: api-gw-test.pkulaw.com
Cookie: CookieId=b97385476b3c721c81a9163f1c8a85dd; SUB=347c9e9e-076c-45e3-be74-c482fffcc6e5; preferred_username=test; session_state=458053bd-5970-4200-9b6f-cf538ec9808b
Content-Length: 508
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW
----WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="folder"
app/icon
----WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="domain"
https://static.pkulaw.com
----WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="fileName"
xzcf.png
----WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="multipartFile"; filename="/C:/Users/User/Pictures/21111.png"
Content-Type: image/png
(data)
----WebKitFormBoundary7MA4YWxkTrZu0gW--
开发过程中的一些坑
- 参数拼接错误,form-data的文件流应该是第一个参数
服务端收到的请求体和参数为空
- 后端服务直接报错,原因有以下几个
- 有空的boundary,
- boundary与字段之间没有\r\n换行
- 将所有\n替换为\r\n,可能会解决上传文件和参数在接收端为空的问题
- http请求头中的boundary是没有开头的两个减号的,这块非常容易出错,例如
ngx.req.set_header("Content-Type", "multipart/form-data; boundary=" .. boundary)
- boundary在各字段之前并不相同,需要着重看一下,一般是------开头,看看是否-的数量不同,可能接收端会有下面的错误,表示请求体拼接不正确
Failed to parse multipart servlet request; nested exception is java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: Stream ended unexpectedly
file-upload-proxy文件上传转发插件源码
-- author: zhangzhanling
-- 文件上传服务代理
-- 代理前端,与文件上传服务进行通讯
-- 在请求体中,添加统一的参数
local core = require("apisix.core")
local uuid = require("resty.jit-uuid")
local ngx = require("ngx")
-- 定义原数据格式
local schema = {
type = "object",
properties = {
folder = {
type = "string",
description = "相对目录"
},
domain = {
type = "string",
description = "图片服务的域名"
}
}
}
local _M = {
version = 0.1,
priority = 1009, --数值超大,优先级越高,因为authz-keycloak是2000,它需要在authz-keycloak之后执行,所以把它定为1000,因为咱们也依赖proxy_rewrite插件
name = "file-upload-proxy",
schema = schema
}
local function get_specific_header(ctx, header_name)
local headers = core.request.headers(ctx)
local value = headers[header_name]
if type(value) == "table" then
return table.concat(value, ", ")
else
return value
end
end
-- 辅助函数:查找边界字符串
local function find_boundary(content_type)
return content_type:match("boundary=([^;]+)")
end
function _M.rewrite(conf, ctx)
ngx.req.read_body()
local body_data = ngx.req.get_body_data()
if not body_data then
core.log.warn("Failed to read request body.")
return 400
end
local content_type = ngx.req.get_headers()["content-type"]
local boundary = find_boundary(content_type)
if not boundary then
core.log.warn("No boundary found in content type.")
return 400
end
local startBoundary = "--" .. boundary
local sub_value = get_specific_header(ctx, "sub")
local folder = conf.folder
if sub_value then
folder = folder .. "/" .. sub_value
end
---- 构建新的请求体
local new_body = ""
local fileExt = ".jpg"
local filename = string.match(body_data, 'filename="([^"]+)"')
if filename then
-- 从filename中提取扩展名
local _, _, ext = string.find(filename, "%.([^.]+)$")
if ext then
core.log.info("文件扩展名为: " .. ext)
fileExt = "." .. ext;
end
end
-- 添加新字段
local new_fields = {
{ name = "domain", value = conf.domain },
{ name = "fileName", value = uuid() .. fileExt },
{ name = "folder", value = folder }
}
---- 添加新字段
for _, field in ipairs(new_fields) do
new_body = new_body .. string.format("\r\n%s\r\nContent-Disposition: form-data; name=\"%s\"\r\n\r\n%s", startBoundary, field.name, field.value)
end
new_body = new_body .. "\r\n" .. body_data
-- 设置新的请求体
ngx.req.set_body_data(new_body)
-- 更新 Content-Type 头
ngx.req.set_header("Content-Type", "multipart/form-data; boundary=" .. boundary)
-- 计算并设置 Content-Length
local content_length = string.len(new_body)
ngx.req.set_header("Content-Length", content_length)
-- 日志输出新请求体和内容长度
core.log.warn("boundary:", boundary)
core.log.warn("New request body: ", new_body)
core.log.warn("Content-Length: ", content_length)
end
-- 注册插件
return _M