feat: enable mirror on demand (#30)

Author: spacewander

README.md

@@ -7,3 +7,9 @@
 default: off
 
 Delay client_max_body_size check until the body is read.
+
+### apisix_mirror_on_demand [on|off]
+
+default: off
+
+Disable request mirror until we enable it in the Lua code.

lib/resty/apisix/client.lua

@@ -17,6 +17,9 @@ typedef unsigned char   u_char;
 ngx_int_t
 ngx_http_apisix_client_set_max_body_size(ngx_http_request_t *r, off_t bytes);
 
+ngx_int_t
+ngx_http_apisix_enable_mirror(ngx_http_request_t *r);
+
 ngx_int_t
 ngx_http_apisix_set_real_ip(ngx_http_request_t *r, const u_char *text, size_t len,
                             unsigned int port);
@@ -35,6 +38,17 @@ function _M.set_client_max_body_size(bytes)
 end
 
 
+function _M.enable_mirror()
+    local r = get_request()
+    local ret = C.ngx_http_apisix_enable_mirror(r)
+    if ret == NGX_ERROR then
+        return nil, "error while disaling mirror"
+    end
+
+    return true
+end
+
+
 function _M.set_real_ip(ip, port)
     -- APISIX will ensure the IP and port are valid
     if not port then

patch/1.19.9/nginx-mirror.patch

@@ -0,0 +1,70 @@
+diff --git src/http/modules/ngx_http_mirror_module.c src/http/modules/ngx_http_mirror_module.c
+index 787adb3..61d0fd3 100644
+--- src/http/modules/ngx_http_mirror_module.c
++++ src/http/modules/ngx_http_mirror_module.c
+@@ -8,10 +8,16 @@
+ #include <ngx_config.h>
+ #include <ngx_core.h>
+ #include <ngx_http.h>
++#if (NGX_HTTP_APISIX)
++#include <ngx_http_apisix_module.h>
++#endif
+ 
+ 
+ typedef struct {
+     ngx_array_t  *mirror;
++#if (NGX_HTTP_APISIX)
++    ngx_flag_t    on_demand;
++#endif
+     ngx_flag_t    request_body;
+ } ngx_http_mirror_loc_conf_t;
+ 
+@@ -33,6 +39,15 @@ static ngx_int_t ngx_http_mirror_init(ngx_conf_t *cf);
+ 
+ static ngx_command_t  ngx_http_mirror_commands[] = {
+ 
++#if (NGX_HTTP_APISIX)
++    { ngx_string("apisix_mirror_on_demand"),
++      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
++      ngx_conf_set_flag_slot,
++      NGX_HTTP_LOC_CONF_OFFSET,
++      offsetof(ngx_http_mirror_loc_conf_t, on_demand),
++      NULL },
++#endif
++
+     { ngx_string("mirror"),
+       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+       ngx_http_mirror,
+@@ -99,6 +114,12 @@ ngx_http_mirror_handler(ngx_http_request_t *r)
+         return NGX_DECLINED;
+     }
+ 
++#if (NGX_HTTP_APISIX)
++    if (mlcf->on_demand && !ngx_http_apisix_is_mirror_enabled(r)) {
++        return NGX_DECLINED;
++    }
++#endif
++
+     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "mirror handler");
+ 
+     if (mlcf->request_body) {
+@@ -186,6 +207,9 @@ ngx_http_mirror_create_loc_conf(ngx_conf_t *cf)
+     }
+ 
+     mlcf->mirror = NGX_CONF_UNSET_PTR;
++#if (NGX_HTTP_APISIX)
++    mlcf->on_demand = NGX_CONF_UNSET;
++#endif
+     mlcf->request_body = NGX_CONF_UNSET;
+ 
+     return mlcf;
+@@ -198,6 +222,9 @@ ngx_http_mirror_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
+     ngx_http_mirror_loc_conf_t *prev = parent;
+     ngx_http_mirror_loc_conf_t *conf = child;
+ 
++#if (NGX_HTTP_APISIX)
++    ngx_conf_merge_value(conf->on_demand, prev->on_demand, 0);
++#endif
+     ngx_conf_merge_ptr_value(conf->mirror, prev->mirror, NULL);
+     ngx_conf_merge_value(conf->request_body, prev->request_body, 1);
+ 

src/ngx_http_apisix_module.c

@@ -472,3 +472,29 @@ ngx_http_apisix_set_real_ip(ngx_http_request_t *r, const u_char *text, size_t le
 
     return NGX_OK;
 }
+
+
+ngx_int_t
+ngx_http_apisix_enable_mirror(ngx_http_request_t *r)
+{
+    ngx_http_apisix_ctx_t       *ctx;
+
+    ctx = ngx_http_apisix_get_module_ctx(r);
+
+    if (ctx == NULL) {
+        return NGX_ERROR;
+    }
+
+    ctx->mirror_enabled = 1;
+    return NGX_OK;
+}
+
+
+ngx_int_t
+ngx_http_apisix_is_mirror_enabled(ngx_http_request_t *r)
+{
+    ngx_http_apisix_ctx_t          *ctx;
+
+    ctx = ngx_http_apisix_get_module_ctx(r);
+    return ctx != NULL && ctx->mirror_enabled;
+}

src/ngx_http_apisix_module.h

@@ -26,6 +26,7 @@ typedef struct {
     ngx_http_apisix_gzip_t *gzip;
 
     unsigned             client_max_body_size_set:1;
+    unsigned             mirror_enabled:1;
 } ngx_http_apisix_ctx_t;
 
 
@@ -39,5 +40,7 @@ ngx_int_t ngx_http_apisix_get_gzip_buffer_conf(ngx_http_request_t *r,
     ngx_int_t *num, size_t *size);
 ngx_int_t ngx_http_apisix_get_gzip_compress_level(ngx_http_request_t *r);
 
+ngx_int_t ngx_http_apisix_is_mirror_enabled(ngx_http_request_t *r);
+
 
 #endif /* _NGX_HTTP_APISIX_H_INCLUDED_ */

t/mirror.t

@@ -0,0 +1,77 @@
+use t::APISIX_NGINX 'no_plan';
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: mirror
+--- config
+location /mirror {
+    content_by_lua_block {
+        ngx.log(ngx.WARN, "mirror request with ", ngx.req.get_method())
+    }
+}
+location /t {
+    mirror /mirror;
+    content_by_lua_block {
+        ngx.exit(200)
+    }
+}
+--- request
+POST /t
+blahblah
+--- grep_error_log eval
+qr/mirror request with \w+/
+--- grep_error_log_out
+mirror request with POST
+
+
+
+=== TEST 2: mirror on demand
+--- config
+location /mirror {
+    content_by_lua_block {
+        ngx.log(ngx.WARN, "mirror request with ", ngx.req.get_method())
+    }
+}
+location /t {
+    mirror /mirror;
+    apisix_mirror_on_demand on;
+    content_by_lua_block {
+        ngx.exit(200)
+    }
+}
+--- request
+POST /t
+blahblah
+--- grep_error_log eval
+qr/mirror request with \w+/
+--- grep_error_log_out
+
+
+
+=== TEST 3: mirror on demand, enabled
+--- config
+location /mirror {
+    content_by_lua_block {
+        ngx.log(ngx.WARN, "mirror request with ", ngx.req.get_method())
+    }
+}
+location /t {
+    mirror /mirror;
+    apisix_mirror_on_demand on;
+    access_by_lua_block {
+        local client = require("resty.apisix.client")
+        assert(client.enable_mirror())
+    }
+    content_by_lua_block {
+        ngx.exit(200)
+    }
+}
+--- request
+POST /t
+blahblah
+--- grep_error_log eval
+qr/mirror request with \w+/
+--- grep_error_log_out
+mirror request with POST