Add support for Brotli

Co-authored-by: Mathieu Lonjaret <mathieu.lonjaret@gmail.com>
Co-authored-by: Tom Moulard <tom.moulard@traefik.io>
Co-authored-by: Romain <rtribotte@users.noreply.github.com>
Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

docs/content/middlewares/http/compress.md

@@ -5,23 +5,24 @@ description: "Traefik Proxy's HTTP middleware lets you compress responses before
 
 # Compress
 
-Compress Responses before Sending them to the Client
+Compress Allows Compressing Responses before Sending them to the Client
 {: .subtitle }
 
 ![Compress](../../assets/img/middleware/compress.png)
 
-The Compress middleware uses gzip compression.
+The Compress middleware supports gzip and Brotli compression.
+The activation of compression, and the compression method choice rely (among other things) on the request's `Accept-Encoding` header.
 
 ## Configuration Examples
 
 ```yaml tab="Docker"
-# Enable gzip compression
+# Enable compression
 labels:
   - "traefik.http.middlewares.test-compress.compress=true"
 ```
 
 ```yaml tab="Kubernetes"
-# Enable gzip compression
+# Enable compression
 apiVersion: traefik.containo.us/v1alpha1
 kind: Middleware
 metadata:
@@ -31,7 +32,7 @@ spec:
 ```
 
 ```yaml tab="Consul Catalog"
-# Enable gzip compression
+# Enable compression
 - "traefik.http.middlewares.test-compress.compress=true"
 ```
 
@@ -42,13 +43,13 @@ spec:
 ```
 
 ```yaml tab="Rancher"
-# Enable gzip compression
+# Enable compression
 labels:
   - "traefik.http.middlewares.test-compress.compress=true"
 ```
 
 ```yaml tab="File (YAML)"
-# Enable gzip compression
+# Enable compression
 http:
   middlewares:
     test-compress:
@@ -56,7 +57,7 @@ http:
 ```
 
 ```toml tab="File (TOML)"
-# Enable gzip compression
+# Enable compression
 [http.middlewares]
   [http.middlewares.test-compress.compress]
 ```
@@ -65,23 +66,34 @@ http:
 
     Responses are compressed when the following criteria are all met:
 
-    * The response body is larger than the configured minimum amount of bytes (default is `1024`).
-    * The `Accept-Encoding` request header contains `gzip`.
+    * The `Accept-Encoding` request header contains `gzip`, `*`, and/or `br` with or without [quality values](https://developer.mozilla.org/en-US/docs/Glossary/Quality_values).
+    If the `Accept-Encoding` request header is absent, it is meant as br compression is requested.
+    If it is present, but its value is the empty string, then compression is disabled.
     * The response is not already compressed, i.e. the `Content-Encoding` response header is not already set.
-
-    If the `Content-Type` header is not defined, or empty, the compress middleware will automatically [detect](https://mimesniff.spec.whatwg.org/) a content type.
-    It will also set the `Content-Type` header according to the detected MIME type.
+    * The response`Content-Type` header is not one among the [excludedContentTypes options](#excludedcontenttypes).
+    * The response body is larger than the [configured minimum amount of bytes](#minresponsebodybytes) (default is `1024`).
 
 ## Configuration Options
 
 ### `excludedContentTypes`
 
+_Optional, Default=""_ 
+
 `excludedContentTypes` specifies a list of content types to compare the `Content-Type` header of the incoming requests and responses before compressing.
 
 The responses with content types defined in `excludedContentTypes` are not compressed.
 
 Content types are compared in a case-insensitive, whitespace-ignored manner.
 
+!!! info "In the case of gzip"
+
+    If the `Content-Type` header is not defined, or empty, the compress middleware will automatically [detect](https://mimesniff.spec.whatwg.org/) a content type.
+    It will also set the `Content-Type` header according to the detected MIME type.
+
+!!! info "gRPC"
+
+    Note that `application/grpc` is never compressed.
+
 ```yaml tab="Docker"
 labels:
   - "traefik.http.middlewares.test-compress.compress.excludedcontenttypes=text/event-stream"
@@ -130,9 +142,9 @@ http:
 
 ### `minResponseBodyBytes`
 
-`minResponseBodyBytes` specifies the minimum amount of bytes a response body must have to be compressed.
+_Optional, Default=1024_
 
-The default value is `1024`, which should be a reasonable value for most cases.
+`minResponseBodyBytes` specifies the minimum amount of bytes a response body must have to be compressed.
 
 Responses smaller than the specified values will not be compressed.
 

docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

@@ -749,7 +749,8 @@ spec:
                   excludedContentTypes:
                     description: ExcludedContentTypes defines the list of content
                       types to compare the Content-Type header of the incoming requests
-                      and responses before compressing.
+                      and responses before compressing. `application/grpc` is always
+                      excluded.
                     items:
                       type: string
                     type: array

docs/content/reference/dynamic-configuration/traefik.containo.us_middlewares.yaml

@@ -172,7 +172,8 @@ spec:
                   excludedContentTypes:
                     description: ExcludedContentTypes defines the list of content
                       types to compare the Content-Type header of the incoming requests
-                      and responses before compressing.
+                      and responses before compressing. `application/grpc` is always
+                      excluded.
                     items:
                       type: string
                     type: array