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Static file

Nginx is famous for its high performance and is commonly used as a front-end reverse proxy server. Nginx is also a high-performance static file server. Usually the static files of the application will be processed using nginx.

The static file that configures nginx has two instructions, a root and an alias. For these two instructions, whether it is necessary to add a slash at the end of the path is often confusing. This paper sums up a more general configuration by trying different matching rules.

Basic configuration

Like the experiment on location url configuration in Nginx Location Url, this article also uses nginx in the vagrant virtual machine. The basic configuration is as follows:

/ etc/nginx/sites-enabled/pro.conf

Server {listen 80 default_server; server_name localhost; access_log / var/log/nginx/pro/access.log; error_log / var/log/nginx/pro/error.log; error_page 404 / 404.html; root / vagrant/pro; index index.html index.htm;}

The directory of the project is as follows:

Pro tree. ├── 403.html ├── 404.html ├── index.html ├── static │ ├── flask │ │ └── m.png │ └── stc.jpg └── upload └── up.png3 directories, 6 files

There are two static folders, one is static and the other is upload.

First acquaintance of root

Root is the root directory of the specified project and applies to server and location. You can specify more than one, and if locaiton does not specify it, it looks for inheritance in its outer server or http.

Visit https://cache.yisu.com/upload/information/20200622/115/58290.jpg and you will find that the picture has been returned. We haven't configured location yet, why did we find the file correctly? When learning the root or alias instructions, the best way is to add a character to the file extension so that the file does not exist on the hard drive, then you can see how nginx looks for the file in nginx's error.log.

Visit https://cache.yisu.com/upload/information/20200622/115/58290.jpgx, and then look at the / var/log/nginx/pro/error.log file, and you can see the following error message:

07:41:48 on 2016-09-28 [error] 4416: 0: * 70 open () "/ vagrant/pro/static/stc.jpgx" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / static/stc.jpgx HTTP/1.1", host: "192.168.33.10"

That is, / vagrant/pro/static/stc.jpgx file does not exist. It's true that we don't have this file. If the file name is correct, it can be accessed because because root / vagrant/pro is specified in the server, the nginx looks for the file in that directory, and the address on the url happens to be the same as the path to the file

Http://192.168.33.10 / static/stc.jpg / vagrant/pro / static/stc.jpg

It can be guessed that the address of the root instruction in nginx actually replaces the host in the matched url.

Root instruction

In order to verify the above conjecture, we need to write more location to do experiments. Add a location configuration as follows:

Location ^ ~ / static {root / vagrant/pro/static;}

Visit https://cache.yisu.com/upload/information/20200622/115/58290.jpg again and find that the image cannot be displayed. Check the error.log and return the following:

07:48:57 on 2016-09-28 [error] 5978: 0: * 71 open () "/ vagrant/pro/static/static/stc.jpg" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / static/stc.jpg HTTP/1.1", host: "192.168.33.10"

Nginx recognizes the address as / vargrant/pro/static/static/stc.jpg with an extra static, and applies the above rule, which combines 192.168.33.10 = / vagrant/pro/static and url is / static/stc.jpg. You can get / vagrant/pro/static + / static/stc.jpg by replacement. Consistent with the wrong error. The solution is to remove the static from the root and access the images immediately.

If so, what happens if you name the folder static stc?

Location ^ ~ / static {root / vagrant/pro;}

An error was obtained when accessing https://cache.yisu.com/upload/information/20200622/115/58290.jpg:

07:54:46 on 2016-09-28 [error] 5992: 0: * 73 open () "/ vagrant/pro/static/stc.jpg" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / static/stc.jpg HTTP/1.1", host: "192.168.33.10"

Calculate the path / vagrant/pro + / static/stc.jpg, cannot find the / vagrant/pro/static/stc.jpg file, conform to the rules mentioned earlier, and try to modify location:

Location ^ ~ / stc {root / vagrant/pro;}

Because url has changed, visit https://cache.yisu.com/upload/information/20200622/115/58312.jpg to find the picture. Now change the stc folder back to static.

Root and slash

Many people will wonder whether the last slash of the path should be added. The slash after the static in location is related to the matched url and will not be repeated. The slash / of the path in root can be determined by experiments. Configure location as follows:

Location ^ ~ / static/ {root / vagrant/pro/;}

Accessing https://cache.yisu.com/upload/information/20200622/115/58290.jpg is fine, accessing https://cache.yisu.com/upload/information/20200622/115/58290.jpg vagrant/pro/static/stc.jpgs error means that the file "/ vagrant/pro/static/stc.jpgs" cannot be found.

If you follow the rule that root replaces host, then the replacement process is

/ vagrant/pro/ + / static/stc.jpg = = / vagrant/pro//static/stc.jpg. In the * nix system, multiple slashes and one slash are equivalent, that is, / vagrant/pro//static/stc.jpg is the same as / vagrant/pro/static/stc.jpg.

In this way, the slash behind the root path will have the same effect with or without. In that case, someone must have thought of this configuration:

Location ^ ~ static/ {root / vagrant/pro;}

If the above algorithm was installed before installation, it should be / vagrant/pro + static/stc.jpg, and the sum should be / vagrant/prostatic/stc.jpg, which is supposed to be an error, but actually can access the image. monstrous absurdity?

If you understand the previous url matching rules of nginx location, you should see that ^ ~ static/ does not match. Modify location

Location ^ ~ static/ {rewrite ^ http://google.com; # root / vagrant/pro;}

You can still get a picture by visiting https://cache.yisu.com/upload/information/20200622/115/58290.jpg, but you don't jump to google, which means it doesn't match ^ ~ static/.

In fact, the principle is also very simple. I still remember that in our first experiment, before location was configured, we could also return pictures. Yes, although ^ ~ static/ does not match, and the outer server defines root as / vagrant/pro, so the search image is returned normally, comment on the outer root, and visit it again. At this point, you will get a 404. Check the error as follows:

08:18:15 on 2016-09-28 [error] 6227: 0: * 82 open () "/ usr/share/nginx/html/static/stc.jpg" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / static/stc.jpg HTTP/1.1", host: "192.168.33.10"

/ usr/share/nginx/html/static/stc.jpg, indicating that there is a root,/usr/share/nginx/html by default even if root,nginx is not specified. Of course, this configuration has nothing to do with ^ ~ static/.

If ~ static/stc.jpgs? Then you can hit, visit the image at this time, and still be able to correctly parse, therefore, there is no such situation as / vagrant/pro + static/stc.jpg. The key to understanding here is that root replaces host and adds the matching url. Of course, the matching url includes the front slash, while the matching url does not.

For ~ static/stc.jpgs? Mode, accessing url https://cache.yisu.com/upload/information/20200622/115/58290.jpg

The url after matching is / static/stc.jpg, and the url of the matching part is static/stc.jpg.

It is important to master this, which is directly related to the relationship between the following alias instructions and slashes.

For root instructions, we can generalize.

For the matched url address, replace the root path in the matched location with the host that accesses the url to get the real address of the file. (multiple slashes are actually equivalent to one slash.) if you do not match the location, look for a more outer root to replace. The last slash of the root instruction can be added or not.

Alias instruction

For root, the operation is very simple, as long as the root address is replaced by host, the file is in the hard disk path (real address). For alise, instead of replacing the matched url address, it replaces the url of the matching part. There can also be multiple alias instructions.

Add a location in almost the same way as root:

Location ^ ~ / upload {alias / vagrant/pro;}

Visit https://cache.yisu.com/upload/information/20200622/115/58321.png and have no pictures. Check error to get:

08:36:18 on 2016-09-28 [error] 6312: 0: * 90 open () "/ vagrant/pro/up.png" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / upload/up.png HTTP/1.1", host: "192.168.33.10"

You can see that the mode of alias is not / vagrant/pro + / upload/up.png, but / vagrant/pro + / up.png.

The word alias is commonly used in computers. It literally means "alias". As the name suggests, it means a different name. The actual replacement rule is to replace the matching url address with the path in alias. For example, the replacement process of the above example can be simulated as follows:

Process mode or urlurl mode ^ ~ / uploadalias path / vagrant/pro access address address / upload + / up.png replacement / upload = = / vagrant/pro result / vagrant/pro + / up.png

To modify the access to the image, modify the locaton as follows:

Location ^ ~ / upload {alias / vagrant/pro/upload;}

At this point, you can get the correct picture by visiting https://cache.yisu.com/upload/information/20200622/115/58321.png. The above calculation process is imitated as follows:

Process mode or urlurl mode ^ ~ / uploadalias path / vagrant/pro/upload access address address / upload + / up.png replacement / upload = = / vagrant/pro/upload result / vagrant/pro/upload + / up.png

As can be seen from the result, the file path is found correctly. If the alias instruction path is added with a slash, then the file path for calculation processing is:

/ upload = / vagrant/pro/upload/vagrant/pro/upload/ + / up.png

Multiple slashes are legal. Equivalent to the case of a slash.

Modify the locaiton as follows:

Location ^ ~ / upload/ {alias / vagrant/pro/upload;}

In this case, the url of the match becomes / upload/ + up.jpg, then the result of the replacement is / vagrant/pro/upload + up.png, and the path of / vagrant/pro/uploadup.png is illegal. You can also see the replacement error in error:

08:52:44 on 2016-09-28 [error] 6452: 0: * 92 open () "/ vagrant/pro/uploadup.png" failed (2: No such file or directory), client: 192.168.33.1, server: localhost, request: "GET / upload/up.png HTTP/1.1", host: "192.168.33.10"

The solution is also simple: change / vagrant/pro/upload to / vagrant/pro/upload/. Thus, the slash at the end of the alias is not as optional as the root instruction, and whether it is needed or not depends on the url matching pattern that works with loacation.

In the previous root mode, considering the slash without a root (~ static/stc.jpgs?), it is difficult to catch errors in the alias case. If the locaion configuration is as follows:

Location ^ ~ upload/ {alias / vagrant/pro/upload/;}

The file path for replacement should be / vagrant/pro/upload/up.png, but in actual testing, configuring alias will always result in a 301 redirection, and a 403 error will be thrown if the alias directory does not open autoindex. The details are not known yet. I don't know if it is the bug of nginx. To avoid this, when using alias, try not to configure the mode where location is ^ ~ upload/, and do not specify url from the root, which is nondescript.

One of the advantages of alise as an alias over root is that the path on the url is not necessarily the same as the file path, because alise does not replace the host, but replaces the host of the matching part. Modify the configuration as follows:

Location ^ ~ / upload/ {alias / vagrant/pro/static/;}

Access to https://cache.yisu.com/upload/information/20200622/115/58339.jpg or https://cache.yisu.com/upload/information/20200622/115/58357.png can correctly access the files in the static directory, even though the url is upload.

The replacement rule is also simple: / upload/ = = / vagrant/pro/static/ to get / vagrant/pro/static/ + stc.jpg or / vagrant/pro/static/ + flask/m.png.

Summary

In the static file configuration of nginx, both root and alias instructions can be implemented. To avoid confusion, try not to write url patterns that have no root path, that is, avoid the beginning of static/, where the slash of the root path needs to be preserved, and it's strange to have no root path.

The main difference between root and alias lies in the replacement part. In root mode, the path configured by root will replace the host in the matched url. Alias replaces the matching part of the url with the path he specified. The slash in the instruction has no effect on the root instruction, but for alise, it can be matched according to the replacement rule.

Root instruction

Location / dir/ root root_path-> http://host/dir/file.txt-> root_path/dir/file.txt

Alias instruction

Location / diralias alias_path-> http://host / dir/ file.txt-> alias_path/file.txtlocation / dir/ alias alias_path/-> http://host / dir/ file.txt-> alias_path/file.txt

After learning about root and alise, it's usually best to configure the root root of one project and use alias for other folders. After all, alias is more flexible.

The above is the whole content of this article, I hope it will be helpful to your study, and I also hope that you will support it.

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