Nginx etag last modified. I have a two phase setup commonly implemented with S3.

Nginx etag last modified Not sure what we should do about it really, following nginx configuration helps: extraConfig Mar 18, 2024 · An HTTP response may pass by one or more proxy servers on its route to the client. 3开始新加了一个etag参数，默认是打开的。 HTTP/1. The server is configured with Ubuntu 20. Instead of stripping all ETags, I would propose to only strip strong ETags. I have looked through various posts and blogs but could not find the correct way to remove it. Dec 24, 2019 · Even if I add these options, the response contains Last-Modified header. For ETags to be useful they should be accompanied with a check for If-None-Match header. 11. If they don't match, the server sends the new resource with a new ETag. I figured this was caused by the loaded "include" module. This header serves the same purpose as ETag, but uses a time-based strategy to determine if a resource has changed, as opposed to the content-based strategy of ETag. 0 and Chrome 54. ETag and Last-Modified have a very similar purpose, but the semantic is different. I'm using proxy_pass). 如果一只后端汪正常地配置了生产环境, 并没有在缓存方面做一些配置, 那默认就是 当有 if_modified_since 和 if_none_match 请求头时， Nginx 先比较 if_modified_since 和 last_modified，Nginx 提供了 if_modified_since 的配置指令，通过配置不同的值，会影响 if_modified_since 和 last_modified 的比较结果。如果 if_modified_since 配置为 off,直接返回 200。 Nov 2, 2012 · Create / edit your . 0, and MariaDB to host my WordPress website. But so far the module doesn't change them when transforming the response to SXG. org Jan 23, 2020 · The last modification date seems to be a real date that doesn’t change with every request. 1, PHP 8. All I could find regarding Both the Etag and the Last-Modified date can be used to avoid downloading the entity body when the version in your cache is already up-to-date, but the Etag is designed specifically for this purpose and has a couple advantages: Sep 28, 2018 · 理论上是ETag优先于Last-Modified，但是Nginx一会把这两个一起开启一起验证，而且Nginx ETag的计算方式把最后修改时间也算进去了。 Nginx ETag计算方式：计算页面文件的最后修改时间，将文件最后修改时间的秒级Unix时间戳转为16进制作为etag的第一部分 计算页面文件的 Feb 24, 2017 · Last-Modified:Thu, 19 Jan 2017 19:17:33 GMT Server:nginx/1. Apr 26, 2019 · NGINX picks up the "not quite written file" and the associated entropy (zero-stuffing) , and the mangled file is now cached downstream with an Etag that won't change, even though the contents of the file do. 1. This is useful if the cache is Mar 15, 2021 · HTTP/1. 测试结果: 两者的功能均正常 所以楼主提的问题是正确的, 有了etag即使没有last-modified也还是可以与服务器交换资源是否已经改动的. I am facing a rather odd issue with my web server. You can look at the header request in Pingdom or use Chrome DevTools to see the value of the last-modified header. Mar 7, 2017 · add_header Cache-Control max-age=5; 缓存5秒，如果没有Last-Modified（即设置了 add_header Last-Modified "";） ，期间会一直直接请求服务器，服务器一直返回200，如果有设置Last-Modified，5秒后会请求一次服务器，5秒前会返回304. If I tell nginx (ssi_last_modified on;) Sep 13, 2019 · nginx有些版本同时开启gzip和etag会出现一些问题. It is also used to Oct 30, 2015 · I'm using upstream module and proxy_pass for reverse proxy, and I enabled etag function by etag on within the server block. One such mechanism is the use of etags for cache validation. 1 origin server is to send both a strong entity tag and a Last-Modified value. org | & fgrep -e HTTP/ -e Date: -e Server: -e Length: -e Modified: -e ETag: HTTP/1. Apr 22, 2018 · You may want to make it look like a file is always modified: add_header Last-Modified $date_gmt; if_modified_since off; etag off; As for the last line, if you really want to hide a true last-modified date, then you must hide the ETag header too since it leaks timestamps. embedded)? From the source code: http://lxr. (js|css|jpg|jpeg|png| gif|js|css|ico|swf)$ { expires 1y; etag off; if_modified_since off; add_header Cache-Control "public, no-transform"; } Set the Last-Modified date to the last time the resource was changed. Feb 17, 2016 · using System; using System. Both Modified-Since and ETag can be used to identify a specific variant of a resource. New York Times assets are also cached for a long time with both Etag and Last-Modified date provided. location ^~ /AWSS3/ { # Prevent Client headers from going to nginx. 14. д. org/ident?_i=ngx_http_set_etag. Based on the RFC 7232 : Dec 23, 2019 · 这个记号告诉客户端，当前网页在上次请求之后是否有发生变化，当发生变化时，ETag的值重新计算，并返回200状态码。如果没有变化，返回304状态码。从而不会重新加载整个页面信息。以下会告诉你，Nginx如何开启ETag。步_nginx lastmodified add_header Last-Modified $date_gmt; if_modified_since off; etag off; As for the last line, if you really want to hide a true last-modified date, then you must hide the ETag header too since it leaks timestamps . files cache for one year and I also got this ETag + Last-Modified headers enabled. A proxy can also cache HTTP responses. Also Nginx uses them while serving static files. Jun 15, 2009 · If-Modified-Since is compared to the Last-Modified whereas If-None-Match is compared to ETag. You can see on lines 1830 and 1831 that the input is the last modified time and the content length. 位置: HTTP Response Header; 说明: 第一次请求时，服务器会在响应头里设置该参数，告诉浏览器该资源的最后修改时间。 # 示例 Last-Modified: Tue, 12 Jan 2010 13:48:00 GMT; If-Modified-Since. The whole ETag generated in C with one line: printf("\"%" PRIx64 "-%" PRIx64 "\"", last_mod, file_size) My proposition is to take Nginx schema and make it as a recommended ETag algorithm by W3C. By far the most common case is that web servers serving static files can use the files' modification time to set the Last-Modified header. 10. Requests with ‘if-none-match’ should honor that etag. S: I think I found it Feb 15, 2019 · Now that we’re generating files according to plan, we need to start serving them with the appropriate cache headers from our server. But it is very easy to disable ETag in NGINX. 1 200 OK Server: nginx/1. Sep 15, 2016 · On nginx 1. AspNetCore. Last-Modified: Sun, 22 Apr 2018 08:48:44 GMT X-Cached: MISS Mar 16, 2011 · Last-Modified and ETag are "weak caching headers" First the browser checks Expires/Cache-Control to determine whether or not to make a request to the servers. Some web servers have built-in support for setting those headers by default, while others leave the headers out entirely unless you explicitly configure them. When both Last-Modified and Etag headers are absent from the origin server response, Smart Edge Revalidation will use the time the object was cached on Cloudflare’s edge as the Last-Modified header value. Currently a reproducible build is performed were my image contains my static files of a react front-end application. For example, When a user visits a website, these tags help to decide if the version of the file on your computer is old or the same May 1, 2017 · It is sent to see if the file in the browser’s cache has been modified since the last time it was requested. So I wonder: Why do so many websites use the "query string" method, instead of just letting the last-modified header do its work? Should I unset the Last-modified header and just work with query strings? Nov 29, 2017 · It may be possible for the nginx proxy to take charge of whether to send 304, by unconditionally querying the application server (and doing all the work entailed in generating a response) and then deciding whether to send 304, rather than passing on the full response (probably code 200), based on the Last-Modified header in that response, but I Mar 28, 2019 · Unfortunately it also removes the ETag headers, as well as the Last-Modified one too. Feb 10, 2017 · 关于nginx的Etag问题，nginx默认是有Etag的，但是问题就在于：无论你对源代码做了什么改动，比如说改动了注释，改动了空行什么的，ETag都会变。（但实际上，比如我改动了注释，但是这个注释可能对程序员很重要， Nov 20, 2015 · 感觉像是 nginx 在 webrick 返回过来的途中把 etag、Last-Modified 给 drop 掉了，求问各位有没有碰到过类似情况。 winterwhisper #1 2015年11月20日 找到原因了，是因为 nginx 开启了 ssi。 Sep 28, 2021 · Last-Modified. IO; using System. Etag. According to the spec: Dec 4, 2014 · It depends :). Http. When replacing a stale cache entry, its last_modified and etag could be inherited from the old entry if the response code is not 200 or 206. Setting a Last-Modified header is different per request, depending on what dynamic resource is generated. Dec 25, 2015 · Apache对于静态内容默认会返回Last-modified和ETag. 22. The issue is, the server is not sending any Etags or last-modified response headers for HTML pages, leading the browser to always get a 200 OK response, and never 304 Not Modified. 15. Nginx控制浏览器缓存配置. ETag. 位置: HTTP Request Header Jun 13, 2016 · Last-Modified and ETag are stored along with the resource so that the client can check later if the resource has changed (when using must-revalidate). 2840. 4. May 29, 2017 · I am facing the same issue today, the issue is come from the server nginx, first check your nginx run user and group from configuration file: ps aux|grep nginx this will show the nginx path and using nginx -V to find more info. md 一、Nginx 1. 2 Date: Fri, 15 Feb 2019 03:24:45 GMT Content-Type: text/html Content-Length: 4 Last-Modif Like most application servers, Express calculates ETag and Last-Modified based on the content of the file being served - not the name of the file. 1 304 Not Modified Server: nginx/1. HTTP/1. So I learned some things about If-Modified-Since and If-None-Match headers that allows to determine if a resource must be re-sent or not. So I would not say that the Last-Modified header covers all cases that ETag does. 7. Meaning it is a weak etag. What are etags? Allows preserving the “Last-Modified” header field from the original response during SSI processing to facilitate response caching. It has this certain SSIETag directive which is set to "Off" by default - based on the description that leads to "no-etag" notes and to the header disappearing eventually. Jan 18, 2014 · the preferred behavior for an HTTP/1. The server can then respond with a 304 Not Modified status code if the resource is Nov 27, 2017 · It looks like Nginx uses the most reasonable schema so if you implementing try to make it the same. e. 1 Date: Thu, 04 Feb 2021 18:24:05 GMT Last-Modified: Thu, 04 Feb 2021 18:22:39 GMT Connection: keep-alive ETag: "601c3b6f-400" This time, Nginx will respond with 304 Not Modified. It generates ETag only for static files. Then this modified date can be included in the ETag header calculation (don't use it as the Last-Modified header, as it may be in the future). One would think that NGinx wouldn't add the content, but simply return the 304 . css file, the last-modified headers were "updated", making the query string unnecessary. If the presented ETag matches, he MUST NOT perform the request, unless the Date in the Last-Modified-Header Feb 3, 2017 · It equals previously recieved ETag for a given URL. Headers; namespace WebApplication9. ) I would configure the server to listen on the IP with no virtual hosts at all, so that it answers any request made to the IP. Open NGINX configuration Oct 31, 2024 · In next requests, the browser sends the Etag back to the server to see if the file has changed; If the Etag matches, the server responds with a 304 Not Modified status, allowing the browser to continue using its cached version. (Especially if you expect to expand on this resource. cache-control: no-cache last-modified: Wed, 08 Jan 2020 21:54:09 GMT server: nginx. July 2015. 服务端（nginx）收到这两项后，会与资源当前生成的Etag和Last-Modified做比较，如果两者都一致，说明资源没有更新，服务端会返回304空响应；否则，说明资源有更新，服务端会将完整的资源内容返回 Jun 16, 2020 · Static resources from upstream usually have cache related headers, such as ETag and Last-Modified. If the Etag value of the document matches that, the server will send a 304 code instead of 200, and no Nov 8, 2022 · location ~* \. 1 I'm proxying an external website (not under my control) to cache images locally. 强Etag. Why is the last-modified header not updated? When I list the files on the shell through ls -l it clearly shows the file has been modified today: ec2-user ec2-user 15298 Feb 24 20:33 > Are there any specific reasons why nginx has both ETags and the Last > Modified headers being sent? From my understanding, this is a bit redundant > for most situations. 如果我们设置了 Cache-Control 设置了 no-cache 之后；那么每次浏览器对已经设置了 Cache-Control 的资源的请求的时候，都要去服务器端进行一个资源的验证，验证完之后，如果确定这个资源可以使用缓存，他才会读取本地的缓存。 Aug 10, 2023 · The server then compares the current ETag value of the resource with the client's value. . Nov 16, 2024 · The server can leverage from HTTP headers such as ETag, Last-Modified headers to indicate the resource payload should not be resend to the clients. When I unset the Last-Modified header in Apache (ETags are also disabled), Firefox (4. by using rsync or manually setting timestamps after checking the files out (for a script that sets timestamps to the last timestamp a file has been committed, see https May 12, 2014 · Afterwards, I noticed that whenever I saved my style. For Launch, we use NGINX for our HTTP server. Net. 109. Is there a way to prevent it? P. Threading. js file with one express route. We just need to set etag server variable to on/off to enable/disable ETag in NGINX. However, when I check the Header of HTTP response, I didn't find the etag field at all. 01) will not cache any file regardless of whether I set a future Expires header or enable the Cache-Control hea Cache: do not inherit last_modified and etag from stale response. With ETag you identify an entity, with Last-Modified you identify the date of a resource with a resolution of 1 second. 2. This is happening with a simple app. proxy_cache_min_uses sets the number of times an item must be requested by clients before NGINX caches it. the next keep the user and group be the same using this command: I'm trying to disable all the caches in nginx for testing purpose. Extensions; using Microsoft. 49 HTTP/1. By default, NGINX does not assign ETag for dynamic content. 0. ru> date: Fri May 24 22:27:23 2013 +0400 Oct 10, 2018 · If you need to use a regular expression location, there may be another conflicting regular expression location block below - such as location \. 总结：nginx 中 etag 由响应头的 Last-Modified 与 Content-Length 表示为十六进制组合而成。 随手在我的k8s集群里找个 nginx 服务测试一下 $ curl --head 10. It's not client side caching from what I can tell ( Nov 26, 2017 · そこでnginxのETagやLast-Modified等の設定周りを見直してみます。 ISUCON7の予選は、画像へのアクセスをいかに304で処理して帯域を節約できるかが肝でした。 May 3, 2017 · If you serve files from /nix/store, nginx will set last-modified header to unix timestamp 1. So I'm thinking about setting CSS, JS etc. Hello, These last days, I tried to understand how web servers like Nginx deal with cache control of resources like JS, CSS or font files. nginx. How does a web server determine if an ETag value is current? Hot Network Questions Dec 24, 2023 · 上述代码中，etag指令用于启用etag功能，if_modified_since指令用于启用If-Modified-Since头部字段的处理。 通过这样的配置，Nginx会自动为每个资源生成etag值，并在后续请求中进行验证。 May 6, 2024 · Etags are like a special tag or label in Nginx web server, which are types of software to manage websites, put on web files like pictures or pages. You could use location ^~ /css/ instead, which is still a prefix location but takes precedence over all regular expression locations. 简单归纳Last-Modified和max-age（expires）关系 Feb 25, 2015 · (Currently Nginx only does SSL. According to section 14. Unfortunately, all files modified date at file system level is Jan 01 1980, because all image layers should be reproducible. But the comparison of If-Modified-Since to Last-Modified gives you the information whether the cached variant is older or newer whereas the comparison of If-None My server seems to be serving an old js file and ignoring recent changes. Sep 7, 2016 · Nginx prepends a W/ to the etag if gzip is turned on. htaccess file and add the following: FileETag MTime Size Either place the following inside a function or put it at the top of the PHP file that you need etags to work on: Let me make two real-life assumptions: you cannot easily customize the code that generates ETag or Last-Modified for you; you are serving some static files; with this in mind, the most obvious difference is that for files, it's easy for you to either accidentally or purposely change the modification date, thus changing Last-Modified header. Nov 5, 2018 · Last-Modified. Using Cache-Control and ETag Summary - conditional requests using If-None-Match "eTag" don't match content that does not also have a Last-Modified header. I suspect that this is because Firefox is getting "304 Not Modified" header. 97 . 16. (Note: This already happens by default in Nginx or Apache) If you need precise control over when resources are invalidated Aug 8, 2019 · Using curl to test If-None-Match / ETag: %curl -i nginx. Http; using Microsoft. - tugrul/HttpCacheBundle Dec 12, 2013 · Why is the Nginx etag created from last-modified-time and content-length? 2. 为什么说这种情况是最常见的? 仔细想想还真是那么回事, 因为nginx默认开启了last-modified和etag属性. I have a two phase setup commonly implemented with S3. Last-modified header 2. 3 Which was more than a month ago. I want to set ETag and Last-Modified in my Rails application and have them take precedence over the S3 ETag and Last-Modified. Jun 12, 2018 · I have web-application, and there is interface where I can refresh logo of a shop. add_header Cache-Control no-cache; I see that the page itself is not cached, but the images, css, and javascripts are. Those are useful to let a client know if the cache is still fresh or not. If a response exists in the cache and it’s fresh, then the proxy may return the cached response instead of contacting the web server. The clients do not use Etags, they would just query Nginx, which goes to CouchDB with its cached Etag, and then either sends back the cached response, or the new one to the client. The result is that browser will cache indefinitely. As nginx doesn't know what a client will use, it returns both. But I get old logo with old last-modified, although logo url file was changed (you can see query timestamp at the end of url): Cache: do not inherit last_modified and etag from stale response. 1 Date: Sat, 15 Jun 2013 17:11:37 GMT Content-Type: text/css Last-Modified: Sat, 15 Jun 2013 17:11:34 GMT Transfer-Encoding: chunked Connection: keep-alive Content-Encoding: gzip Как видно, здесь нету заговка ETag. g. 26 of RFC 2616, the server MUST NOT respond with a 304 Not Modified, if the ETag presented in a If-None-Match-Header has changed, and the server has to ignore an additional If-Modified-Since-Header, if present. It’s been available across browsers since. Security. Nginx通过添加Cache-Control(max Specifies how to compare modification time of a response with the time in the “If-Modified-Since” request header field: off the response is always considered modified (0. After that I update logo again. Sep 5, 2022 · For example, your PNG or JPEG files served by Nginx will automatically include the HTTP headers for content-length, last-modified, and etag on static files that are not gzipped even if you don't manually enable them May 7, 2015 · Are you working in an environment without a useful clock (eg. pr Jul 29, 2021 · 8. I'm testing with nginx + tornado. Mar 30, 2020 · Etag主要为了解决Last-Modified无法解决的一些问题. Jan 21, 2018 · I'm using Nginx and got a simple (maybe noobie) question about caching but I just want to be sure that I don't do anything bad:P. css. Middleware { // This code is mostly here to generate the ETag from the response body and set Sep 14, 2023 · Let's assume I use etag off (and if_modified_since off with add_header Last-Modified "" to not make redundancy) in NGINX and I generate ETags on upstream (i. 12. This is required to support both clients using Last-Modified as a cache validator, and ETag as a cache validator. Dec 12, 2015 · I'm trying to get my Nginx reverse proxy work properly. How To Disable ETag in NGINX. Cryptography; using System. Jul 23, 2015 · This saves on bandwidth, because the server sends the full item only if it has been modified since the time recorded in the Last-Modified header attached to the file when NGINX originally cached it. Если после изменения My default NGinx installation is returning a 304 Not Modified response to a request which has a matching If-None-Match header and a non-expired If-Modified-Since header which is correct behaviour but NGinx also adds the content of the resource to the 304 response. org/nginx/rev/cbd4bbe976d4 branches: changeset: 5228:cbd4bbe976d4 user: Maxim Dounin <mdounin@mdounin. How to configure Nginx to enable caching Let’s assume that we want to cache the resources that are located in the /static/ folder: Aug 10, 2011 · Use the modified date of the file, but have a build process artificially mutate the modified date of the file based on a hash of the file. It won’t send the file over the network again; instead, it will tell the browser that it can reuse the file it already Nov 22, 2016 · However, even though the Last-Modified date is later than the cached version the browser has, I'm still seeing the old version of the file (tested on Firefox 50. ETag, Last-Modified and their complementaries are used in conditional GET request, when server may respond with 304 Not Modified. Learn more; See full compatibility May 8, 2018 · I wouldn't do this in nginx, I'd do this in your application. 7 Date: Sat, 10 Aug 2019 05:24:06 GMT Content-Length: 9053 Last-Modified: Tue, 23 Jul 2019 12:20:32 GMT ETag: "5d36fb90-235d" %curl -i -H "If-None-Match: 5d36fb90-235d" nginx. It also has a complementary header for client request: If-Modified-Since. Oct 4, 2022 · Describe the Enhancement. I am using a nginx server. When I refresh logo, I gеt new file with new last-modified header: Nginx returns corrected updated file. Etag is helpful since it saves bandwidth and lets the browser only re-download things that have changed. Aug 8, 2020 · If-Modified-Since: Last-Modifiedの値 If-None-Match: "ETag値" 最新であれば（リクエストヘッダの設定値が妥当であれば）、 304 Not Modified が応答されるので、自分が持っているキャッシュを使う。 Проверил без патча и добавлением строки `add_header Last-Modified "";` В ответе генерируется ETag: "1-4e", "1-75" и т. 3. Really, it depends on what does the backend. Last-Modified — resource modification date. By default, the header field is removed as contents of the response are modified during processing and may contain dynamically generated elements or parts that are changed independently of the original response. Dec 19, 2023 · By caching static content, you can significantly reduce the load on your server and improve the overall user experience. If it has to make a request, it will send Last-Modified/ETag in the HTTP request. 04, Nginx v1. Jan 1, 2023 · When the client makes a subsequent request for a resource, it can include the ETag or Last-Modified header in the If-None-Match or If-Modified-Since headers, respectively, to conditionally retrieve the resource only if it has been modified since the last request. Aug 17, 2017 · I don't see any nginx setting to configure how nginx computes the etag, so your only chance with nginx is to ensure that file timestamps are exactly the same, e. Let’s explore the ETag header particularly. Nginx只会返回Last-modified(可配置etag on开启). 0 Date: Tue, 10 Dec 2019 06:45:24 GMT Content-Type: text/html Content-Length: 612 Last-Modified: Tue, 23 Apr 2019 May 3, 2020 · 当再次访问网站时，上次访问留存有expire和etag，last-modified,浏览器是如何处理的？expire在有效期内，是否还发出http请求？如果不发出http请求了，服务器资源更新了，还是从浏览器缓存取了旧资源吗？ add_header Last-Modified “”; Cloudflare Nginx Last modified header. ) CouchDB supports Etags, so ideally what I would like is Nginx caching the Etags as well for dumb clients. Tasks; using Microsoft. #缓存验证 Last-Modified 和 Etag 的使用. 98). Observed behaviour: Requests only honor that etag if the response /also/ contains a ‘last-modified Mar 31, 2022 · 那就是服务端只设置了last-modified 以及 etag, 并没有设置cache-control和expires属性. If they match, the client's cached version is still fresh, and the server returns a 304 Not Modified status, allowing the client to use its cached copy. easily add an ETag to all responses. 强Etag根据配置文件中的配置来设置Etag值，默认的Apache的FileEtag设置为： FileEtag: INode Mtime Size 也就是根据这三个属性来生成Etag值，他们之间通过一些算法来实现，并输出成hex的格式，相邻属性之间用-分隔 NGINX module to override `Last-Modified` and `ETag` response headers - 3dyd/ngx_http_last_modified_filter details: http://hg. Sep 15, 2017 · I want to remove the ETag from my response header. The ETag header is also very similar to the last-modified header. 协议中Etag头信息校验. is there a better way to know if nginx is serving compressed content ? Feb 21, 2019 · Update #3 . Expected behavior: Content cache stores content with etag. I've set the following line. What you likely want instead is: location stuffyoudontwanttocache { # don't cache it proxy_no_cache 1; # even if cached, don't try to use it proxy_cache_bypass 1; } Oct 21, 2015 · This feature is well established and works across many devices and browser versions. 问题在于: 何时应该使用etag? Mar 2, 2019 · 如果服务器端同时设置了Etag和Expires时，Etag原理同样，即与 Last-Modified/Etag 对应的 HttpRequestHeader:If-Modified-Since 和 If-None-Match。 我们可以看到这两个Header的值和WebServer发出的Last-Modified,Etag值完全一样；在完全匹配If-Modified-Since和If-None-Match即检查完修改时间和Etag之后 Dec 2, 2020 · So if your website does not need ETag, better disable it. How can I invalidate the ETag so that whenever I deploy diffs to my static files, the browser understands to reload them? Nov 29, 2017 · And just as with ETags, there may be ways that the web server or framework can automate the creation of the header. The first time a browser requests one of our files, it will receive the the ETag and Last-Modified for the resource. For example, suppose the resource is a dynamically generated image, and the request the cache does is "GET /image If-Modified-Since: 5 minutes ago", the backend might be smart and seeing that there is no new data it might reply with a 304 not modified. Text; using System. sendfile off; if_modified_since off; expires off; etag off; Jan 5, 2023 · I am facing a rather odd issue with my web server. Last-Modified头信息校验 浏览器请求流程. Is it okay to check for strong or weak etags with php using substr() - or am I missing something here . However, I found that once a file is cached, it will never update/revalidate even the backend file is changed, which can be identified by ETa Oct 15, 2020 · 如果服务器端同时设置了Etag和Expires时，Etag原理同样，即与 Last-Modified/Etag 对应的 HttpRequestHeader:If-Modified-Since 和 If-None-Match。 我们可以看到这两个Header的值和WebServer发出的Last-Modified,Etag值完全一样；在完全匹配If-Modified-Since和If-None-Match即检查完修改时间和Etag之后 Dec 23, 2019 · 上述配置将使得Nginx在响应头中添加Etag和Last-Modified两项。然而，仅靠这些设置还不够。如果不配置Cache-Control为no-cache，浏览器在下次请求相同资源时可能会直接从缓存中获取资源，而不会去请求服务器。 4. Symfony bundle that manages HTTP caching with ETag and Last-Modified headers, based on route names and query parameters, optimizing cache validation and integration with proxy servers like Nginx and Varnish. Oct 25, 2016 · The expires and add_header directives have no impact on NGINX caching the files, those are purely about what the browser sees. 34); exact exact match; before modification time of the response is less than or equal to the time in the “If-Modified-Since” request header field. 3 以后的默认打开etag nginx从1. Nginx, a popular web server and reverse proxy server, offers various caching mechanisms to enhance website performance. lovoyht cnd zgl xiqml silg gxz prf yutxnc trbv lkzr