Detailed explanation of nginx location directive

Which nginx variable does location match?

$request_uri

What are the matching types of location?

= starts with Indicates an exact match starting with

^~. Note that this is not a regular expression (it is a string match with increased priority) – its purpose is to take precedence over regular expression matching. If the location is the best match, regular expression detection is no longer performed.

~ The beginning of indicates case-sensitive regular matching;

~* The beginning of indicates case-insensitive regular matching

!~ && !~*: Indicates case-sensitive non-matching regular and case-insensitive non-matching regular

String matching

/Universal matching, if there is no other match, any request will match

location search order

Exact match first =

Secondly match ^~

Then perform regular matching according to the order of the configuration file

Finally, hand it over to/for general matching

Note:

When a match is successful, the matching will be stopped immediately and the request will be processed according to the current matching rules.

Special note: String matching will be searched first, but only the most recent will be recorded. Long match, and then continue to search for regular matches. If there is a regular match, the regular match is hit. If there is no regular match, the longest string match is hit. (If ^~ is the longest match, it will hit directly and stop searching for regular expressions)

Exact match

location = /images/test.png {
    echo 'config1';
}
location  /images/test.png {
    echo 'config2';
}
location \/images\/test\.png$ {
    echo 'config3';
}

If requested at this timehttp:/ /127.0.0.1/images/test.png What will be output?

Output config1, there is no doubt that exact matching has the highest priority!

Special case of exact matching

location = / {
    index index.html;
}
location / {
    echo 'config2';
}

At this time, what will be output if http://127.0.0.1 is entered?

is the output of config2. Why does the exact matching priority not work?

Yes, exact matching still works. When requesting a directory (not a specific file), nginx will internally direct the request to the index file.

The real request at this time is http://127.0.0.1/index.html, this is config2 and it is hit!

, so exact matching should not be used to match /

characters String search and regular search

location /images/test.png {
    echo 'config1';
}
location ^~ /images/ {
    echo 'config2';
}
location ~ \/images\/test\.png$ {
    echo 'config3';
}
location ~ \/images\/ {
    echo 'config4';
}

If you request http://127.0.0.1/images/test.png at this time, what will be output?

is of course config3, and the regular pattern hits

(although config1 is the longest matching string, only recording is done at this time, and the regular matching must be searched later, then config3 Regular match hits),

If you look carefully, you can find that config4 is also matched successfully, but the regular matching order is matched according to the definition order of location, so config3 hits the .

character Improvement of string matching priority (^~)

location /images/ {
    echo 'config1';
}
location ^~ /images/test.png {
    echo 'config2';
}
location ~ /images/test\.png$ {
    echo 'config3';
}
location ~ \/images\/ {
    echo 'config4';
}

If you request http://127.0.0.1/images/test.png at this time, what will be output?

is of course config2, the first match hits

(because string matching is searched first, at this time it is found that config2 is the longest string match and is ^~ Matching method, so stop searching for regular expressions and hit directly!)

So the ^~ symbols here are special, in order to increase the priority of string matching and take precedence over regular matching.

Related recommendations: "Nginx Tutorial"

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