Configure an NGINX cache policy - - Alibaba Cloud Documentation Center

This topic describes how to configure an NGINX cache policy by using the add_header and expires directives of NGINX.

Note

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Run the add_header and expires commands to configure an NGINX cache policy. You can run the commands to specify cache-related fields in HTTP response headers, which affects how browsers and proxy servers cache content.

Procedure

Use the add_header command to specify a custom HTTP header:
```
add_header name value;
```
For example, you can run the following command to create a header Cache-Control to specify that the resource is not cached:
```
add_header Cache-Control "no-cache";
```
Run the following expires command to configure the time-to-live (TTL):
```
expires [time|epoch|max|off];
```
- off: does not allow modifying the Expires or Cache-Control response header.
- time: specifies the time when the cache expires. For example, expires 1h; indicates that the cache expires in 1 hour.
- epoch: sets the Expires header to a timestamp that follows the UNIX time format. It is the number of seconds that have elapsed since 00:00:00 Thursday, January 1, 1970.
- max: sets the Expires header to a future point in time and the Cache-Control header to 10 years.

Sample configurations

Set the TTL of PHP files to 1 hour.
```
location ~ \.php$ {
 expires 1h;
}
```

Set the cache policy for PHP files to no-cache.

location ~ \.php$ {
 add_header Cache-Control "no-cache";
}

This way, you can configure different cache policies for different types of resources or specific locations based on your business requirements.