rewrite_by_lua yuansheng-9.19 · openresty中文api

rewrite_by_lua -------------- **语法:** *rewrite_by_lua <lua-script-str>* **环境:** *http, server, location, location if* **阶段:** *rewrite tail* 作为一个重写阶段的处理程序，为每个请求执行由`<lua-script-str>`指定的 Lua 代码。这些 Lua 代码可以调用[全部 API](#nginx-api-for-lua)，并作为一个新的协程，在一个独立的全局环境中执行（就像一个沙盒）。注意这个处理过程总是在标准[ngx_http_rewrite_module](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html)的 *后* 面。所以下面的示例可以按照预期执行： ```nginx location /foo { set $a 12; # create and initialize $a set $b ""; # create and initialize $b rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; echo "res = $b"; } ``` 因为 `set $a 12` 和 `set $b ""` 的执行都在[rewrite_by_lua](#rewrite_by_lua)的前面。另一方面，下面的示例是不能按照预期执行： ```nginx ? location /foo { ? set $a 12; # create and initialize $a ? set $b ''; # create and initialize $b ? rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; ? if ($b = '13') { ? rewrite ^ /bar redirect; ? break; ? } ? ? echo "res = $b"; ? } ``` 因为 `if` 是[rewrite_by_lua](#rewrite_by_lua)之 *前* 执行的，尽管在配置中它被放到[rewrite_by_lua](#rewrite_by_lua)后面。正确的处理方式应该是这样： ```nginx location /foo { set $a 12; # create and initialize $a set $b ''; # create and initialize $b rewrite_by_lua ' ngx.var.b = tonumber(ngx.var.a) + 1 if tonumber(ngx.var.b) == 13 then return ngx.redirect("/bar"); end '; echo "res = $b"; } ``` 注意，[ngx_eval](http://www.grid.net.ru/nginx/eval.en.html)模块可以近似的使用[rewrite_by_lua](#rewrite_by_lua)。例如： ```nginx location / { eval $res { proxy_pass http://foo.com/check-spam; } if ($res = 'spam') { rewrite ^ /terms-of-use.html redirect; } fastcgi_pass ...; } ``` 在ngx_lua中可以这样实施： ```nginx location = /check-spam { internal; proxy_pass http://foo.com/check-spam; } location / { rewrite_by_lua ' local res = ngx.location.capture("/check-spam") if res.body == "spam" then return ngx.redirect("/terms-of-use.html") end '; fastcgi_pass ...; } ``` 如同其他重写阶段处理， [rewrite_by_lua](#rewrite_by_lua)在子请求中也执行的。注意，在[rewrite_by_lua](#rewrite_by_lua)处理内部，当调用`ngx.exit(ngx.OK)`时，nginx请求将继续下一阶段的内容处理。要在[rewrite_by_lua](#rewrite_by_lua)处理中终结当前请求，调用[ngx.exit](#ngxexit)，成功的请求设定 status >= 200 (`ngx.HTTP_OK`) 并 status < 300 (`ngx.HTTP_SPECIAL_RESPONSE`)，失败的请求设定`ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)` (或其他相关的)。如果使用了[ngx_http_rewrite_module](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html)的[rewrite](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html#rewrite)指令来改变 URI 并发起内部重定向，那么在当前 location 内任何有序的[rewrite_by_lua](#rewrite_by_lua) 或 [rewrite_by_lua_file](#rewrite_by_lua_file)代码都将不被执行。例如： ```nginx location /foo { rewrite ^ /bar; rewrite_by_lua 'ngx.exit(503)'; } location /bar { ... } ```  Here the Lua code `ngx.exit(503)` will never run. This will be the case if `rewrite ^ /bar last` is used as this will similarly initiate an internal redirection. If the `break` modifier is used instead, there will be no internal redirection and the `rewrite_by_lua` code will be executed. `rewrite_by_lua`代码将永远在 `rewrite` 请求处理阶段后面，除非[rewrite_by_lua_no_postpone](#rewrite_by_lua_no_postpone)配置开启。 [返回目录](#directives) > English source: rewrite_by_lua -------------- **syntax:** *rewrite_by_lua <lua-script-str>* **context:** *http, server, location, location if* **phase:** *rewrite tail* Acts as a rewrite phase handler and executes Lua code string specified in `<lua-script-str>` for every request. The Lua code may make [API calls](#nginx-api-for-lua) and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox). Note that this handler always runs *after* the standard [ngx_http_rewrite_module](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html). So the following will work as expected: ```nginx location /foo { set $a 12; # create and initialize $a set $b ""; # create and initialize $b rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; echo "res = $b"; } ``` because `set $a 12` and `set $b ""` run *before* [rewrite_by_lua](#rewrite_by_lua). On the other hand, the following will not work as expected: ```nginx ? location /foo { ? set $a 12; # create and initialize $a ? set $b ''; # create and initialize $b ? rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1'; ? if ($b = '13') { ? rewrite ^ /bar redirect; ? break; ? } ? ? echo "res = $b"; ? } ``` because `if` runs *before* [rewrite_by_lua](#rewrite_by_lua) even if it is placed after [rewrite_by_lua](#rewrite_by_lua) in the config. The right way of doing this is as follows: ```nginx location /foo { set $a 12; # create and initialize $a set $b ''; # create and initialize $b rewrite_by_lua ' ngx.var.b = tonumber(ngx.var.a) + 1 if tonumber(ngx.var.b) == 13 then return ngx.redirect("/bar"); end '; echo "res = $b"; } ``` Note that the [ngx_eval](http://www.grid.net.ru/nginx/eval.en.html) module can be approximated by using [rewrite_by_lua](#rewrite_by_lua). For example, ```nginx location / { eval $res { proxy_pass http://foo.com/check-spam; } if ($res = 'spam') { rewrite ^ /terms-of-use.html redirect; } fastcgi_pass ...; } ``` can be implemented in ngx_lua as: ```nginx location = /check-spam { internal; proxy_pass http://foo.com/check-spam; } location / { rewrite_by_lua ' local res = ngx.location.capture("/check-spam") if res.body == "spam" then return ngx.redirect("/terms-of-use.html") end '; fastcgi_pass ...; } ``` Just as any other rewrite phase handlers, [rewrite_by_lua](#rewrite_by_lua) also runs in subrequests. Note that when calling `ngx.exit(ngx.OK)` within a [rewrite_by_lua](#rewrite_by_lua) handler, the nginx request processing control flow will still continue to the content handler. To terminate the current request from within a [rewrite_by_lua](#rewrite_by_lua) handler, calling [ngx.exit](#ngxexit) with status >= 200 (`ngx.HTTP_OK`) and status < 300 (`ngx.HTTP_SPECIAL_RESPONSE`) for successful quits and `ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)` (or its friends) for failures. If the [ngx_http_rewrite_module](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html)'s [rewrite](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html#rewrite) directive is used to change the URI and initiate location re-lookups (internal redirections), then any [rewrite_by_lua](#rewrite_by_lua) or [rewrite_by_lua_file](#rewrite_by_lua_file) code sequences within the current location will not be executed. For example, ```nginx location /foo { rewrite ^ /bar; rewrite_by_lua 'ngx.exit(503)'; } location /bar { ... } ``` Here the Lua code `ngx.exit(503)` will never run. This will be the case if `rewrite ^ /bar last` is used as this will similarly initiate an internal redirection. If the `break` modifier is used instead, there will be no internal redirection and the `rewrite_by_lua` code will be executed. The `rewrite_by_lua` code will always run at the end of the `rewrite` request-processing phase unless [rewrite_by_lua_no_postpone](#rewrite_by_lua_no_postpone) is turned on. [Back to TOC](#directives)