File compression - Edge Security Acceleration - Alibaba Cloud Documentation Center

Introduction

ESA provides three compression methods: Gzip, Brotli, and Zstd. They differ in compression efficiency, decompression speed, and compatibility, making them suitable for different scenarios.

Compression type	Compression efficiency	Compatibility	Use case
Gzip	Fast compression, medium decompression speed	High	General web services
Brotli	Slow compression, high decompression speed	Medium	Static resource optimization
Zstd	Very fast compression, very fast decompression	Low	Real-time stream data processing

Note

The Entrance plan only supports Zstd compression.

Notes

If you enable Gzip, Brotli, and Zstd at the same time, they are applied in the following order: Zstd > Brotli > Gzip.
ESA supports compression for the following file types: text/xml, text/plain, text/css, application/javascript, application/x-javascript, application/rss+xml, text/javascript, image/tiff, image/svg+xml, application/json, and application/xml.

Cases where compression rules do not take effect

Compression rules are not applied in certain cases because of conflicting settings on the origin server or client.

For origin server

Gzip or Brotli compression is applied only to files from the origin server that are between 1 KB and 10 MB. Files outside this size range are not compressed.
If the response from the origin server includes the Content-Encoding header, ESA does not apply compression.
If the response from the origin server contains the cache-control: no-transform HTTP header, ESA does not apply compression.

For client

If a client does not support the configured compression algorithm, the response is not compressed. Client support is indicated by the Accept-Encoding request header.

Note

File compression rules apply only to requests that match the specified rule conditions. For more information about how to configure site-level compression rules, see Gzip, Brotli, and Zstd.

Add a file compression rule

In the ESA console, select Websites. In the Website column, click the target site.
In the navigation pane on the left, select Rules > Content Optimization.
Click Create Rule and enter a Rule Name.
In the If requests match... section, set the conditions that the request must match. For more information about how to configure rules, see Components of a rule expression.

In the Then execute... section, enable the required compression method.

Rule item	Description
Rule Name	A custom rule name. It can contain Chinese characters, letters (case-sensitive), digits (0-9), and underscores (`_`). The name can be up to 64 characters long.
Matching conditions	Specify the conditions that requests must match. Click the logical operator And or Or to add a condition. You can add up to five conditions to a rule. Each condition consists of a Matching field, a Logical operator, and a Matching content.
Compression method	Enable Gzip, Brotli, or Zstd. When all three are enabled, Zstd has the highest priority, followed by Brotli.

Edge Security Acceleration:File compression