nginx 的ngx_http_addition_module 模块也是一个修改content 的好东西，对于openresty 我们经常使用content_by_lua 阶段处理
但是经过分析ngx_http_addition_module 源码的处理机制，他是基于body_fiter 处理的，所以我们基于content_by_lua 进行数据处理
会有顺序不对的问题
参考源码处理
处理机制
ngx_http_addition_filter_module_ctx上下文定义
static ngx_http_module_t ngx_http_addition_filter_module_ctx = {
NULL, /* preconfiguration */
ngx_http_addition_filter_init, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
ngx_http_addition_create_conf, /* create location configuration */
ngx_http_addition_merge_conf /* merge location configuration */
};
阶段(依赖了header 以及body)
static ngx_int_t
ngx_http_addition_filter_init(ngx_conf_t *cf)
{
ngx_http_next_header_filter = ngx_http_top_header_filter;
ngx_http_top_header_filter = ngx_http_addition_header_filter;
ngx_http_next_body_filter = ngx_http_top_body_filter;
ngx_http_top_body_filter = ngx_http_addition_body_filter;
return NGX_OK;
}
核心处理
static ngx_int_t
ngx_http_addition_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
ngx_int_t rc;
ngx_uint_t last;
ngx_chain_t *cl;
ngx_http_request_t *sr;
ngx_http_addition_ctx_t *ctx;
ngx_http_addition_conf_t *conf;
if (in == NULL || r->header_only) {
return ngx_http_next_body_filter(r, in);
}
ctx = ngx_http_get_module_ctx(r, ngx_http_addition_filter_module);
if (ctx == NULL) {
return ngx_http_next_body_filter(r, in);
}
conf = ngx_http_get_module_loc_conf(r, ngx_http_addition_filter_module);
if (!ctx->before_body_sent) {
ctx->before_body_sent = 1;
if (conf->before_body.len) {
if (ngx_http_subrequest(r, &conf->before_body, NULL, &sr, NULL, 0)
!= NGX_OK)
{
return NGX_ERROR;
}
}
}
if (conf->after_body.len == 0) {
ngx_http_set_ctx(r, NULL, ngx_http_addition_filter_module);
return ngx_http_next_body_filter(r, in);
}
last = 0;
for (cl = in; cl; cl = cl->next) {
if (cl->buf->last_buf) {
cl->buf->last_buf = 0;
cl->buf->last_in_chain = 1;
cl->buf->sync = 1;
last = 1;
}
}
rc = ngx_http_next_body_filter(r, in);
if (rc == NGX_ERROR || !last || conf->after_body.len == 0) {
return rc;
}
if (ngx_http_subrequest(r, &conf->after_body, NULL, &sr, NULL, 0)
!= NGX_OK)
{
return NGX_ERROR;
}
ngx_http_set_ctx(r, NULL, ngx_http_addition_filter_module);
return ngx_http_send_special(r, NGX_HTTP_LAST);
}
如果需要使用的解决方法
可以直接在body_fiter 阶段进行数据处理，注意此阶段会有一些api 的限制
参考处理（直接输出了，比较简单）
location = /flush2.html {
add_before_body /before_action;
add_after_body /after_action;
}
location /before_action {
default_type text/html;
content_by_lua_block {
ngx.say("this is before content\n")
ngx.log(ngx.ERR, "before_action")
}
}
location /after_action {
default_type text/html;
body_filter_by_lua_block {
ngx.arg[1] = "this is after content\n"
}
}
说明
以上是结合源码学习ngx_http_addition_module 与openresty 集成的处理，大家如果碰到类似问题可以参考
参考资料
https://github.com/nginx/nginx/blob/master/src/http/modules/ngx_http_addition_filter_module.c#L133