Response compression

Apoxy compresses HTTP responses by default. All three algorithms (gzip, brotli, zstd) are enabled on every route, with a 128-byte minimum response size and a standard set of compressible MIME types.

No configuration is needed to get compression — it works out of the box. The HTTPRouteFilter extension lets you customize compression behavior on specific routes: change the minimum size, restrict algorithms, override content types, or disable compression entirely.

Verify default compression

curl -H 'Accept-Encoding: gzip' -I https://app.example.com/

You should see:

HTTP/1.1 200 OK
Content-Encoding: gzip

Choosing algorithms

By default, all three algorithms are enabled and Envoy picks the best one based on the client's Accept-Encoding header. To restrict to specific algorithms on a route, create an HTTPRouteFilter:

apiVersion: extensions.apoxy.dev/v1alpha2
kind: HTTPRouteFilter
metadata:
  name: compress-gzip-only
spec:
  compressor:
    algorithms:
    - gzip

Attach it to an HTTPRoute:

apiVersion: gateway.apoxy.dev/v1
kind: HTTPRoute
metadata:
  name: app-route
spec:
  parentRefs:
  - name: default
  hostnames:
  - app.example.com
  rules:
  - filters:
    - type: ExtensionRef
      extensionRef:
        group: extensions.apoxy.dev
        kind: HTTPRouteFilter
        name: compress-gzip-only
    backendRefs:
    - group: core.apoxy.dev
      kind: Backend
      name: app-backend
      port: 8080

Supported values: gzip, brotli, zstd.

Tuning the minimum size

Responses smaller than minContentLength bytes are not compressed. The default is 128 bytes. Compressing very small responses can actually increase their size due to compression overhead.

spec:
  compressor:
    minContentLength: 1024

The minimum allowed value is 50 bytes.

Custom content types

By default, compression applies to common text and structured formats. To override the list on a specific route:

spec:
  compressor:
    contentType:
    - application/json
    - text/html
    - text/plain
    - application/xml

Default content types

When contentType is not specified, the following MIME types are compressed:

• application/javascript
• application/json
• application/xhtml+xml
• image/svg+xml
• text/css
• text/html
• text/plain
• text/xml

Disabling compression on a route

Since compression is enabled by default, you may want to explicitly disable it on specific routes — for example, if the upstream already compresses responses. Use the disabled flag:

apiVersion: extensions.apoxy.dev/v1alpha2
kind: HTTPRouteFilter
metadata:
  name: no-compress
spec:
  compressor:
    disabled: true

When disabled is set to true, no other compressor fields may be specified.

Full spec reference

apiVersion: extensions.apoxy.dev/v1alpha2
kind: HTTPRouteFilter
metadata:
  name: compress-custom
spec:
  compressor:
    # Disable compression entirely. When true, all other fields are forbidden.
    # disabled: true

    # Algorithms to enable. Defaults to all three.
    algorithms:
    - gzip
    - brotli
    - zstd

    # Minimum response body size in bytes to trigger compression.
    # Must be >= 50. Defaults to 128.
    minContentLength: 128

    # MIME types that trigger compression.
    # Defaults to the list above when omitted.
    contentType:
    - application/json
    - text/html
    - text/plain

Key points

• Compression is enabled by default on all routes with a 128-byte minimum size.
• Use HTTPRouteFilter only when you need to customize or disable compression on specific routes.
• One HTTPRouteFilter can be shared across multiple HTTPRoutes — create it once and reference it from any route.
• The client's Accept-Encoding header determines which algorithm is used. If the client doesn't support any of the configured algorithms, the response is sent uncompressed.
• Compression runs after the backend responds, so it does not affect request bodies.
• Binary formats like images and video are typically not compressible. Avoid adding types like image/png or video/mp4 to the content-type list.