14-compression.yml

# 14-compression.yml - Response compression (gzip, brotli, zstd)
#
# This example demonstrates proxy-level response compression. When enabled, the
# proxy compresses upstream responses before sending them to clients. This reduces
# bandwidth usage and improves perceived performance.
#
# The proxy negotiates the best algorithm based on the client's Accept-Encoding header.
#
# Start: sbproxy serve -f examples/14-compression.yml
#
# Request with gzip (most common):
#   curl -H "Host: compressed.example.com" -H "Accept-Encoding: gzip" \
#        --compressed http://localhost:8080/
#
# Request with brotli (smaller than gzip, supported by modern browsers):
#   curl -H "Host: compressed.example.com" -H "Accept-Encoding: br" \
#        --compressed http://localhost:8080/
#
# Request without compression (compare response sizes):
#   curl -H "Host: compressed.example.com" http://localhost:8080/
#
# Check Content-Encoding header in response:
#   curl -v -H "Host: compressed.example.com" -H "Accept-Encoding: gzip,br,zstd" \
#        http://localhost:8080/ 2>&1 | grep -i "content-encoding\|content-length"

proxy:
  http_bind_port: 8080

origins:
  "compressed.example.com":
    action:
      type: proxy
      url: https://test.sbproxy.dev

    # Compression is configured at the origin level.
    # The proxy compresses responses based on the client's Accept-Encoding header.
    compression:
      enable: true                 # Enable proxy-level compression

      # Algorithms listed in preference order.
      # The proxy uses the first algorithm the client supports.
      # Supported: "gzip", "br" (brotli), "zstd" (zstandard), "deflate"
      algorithms:
        - zstd                     # Best compression ratio, modern clients only
        - br                       # Brotli: better than gzip, widely supported
        - gzip                     # Gzip: universal fallback, always supported

      # Minimum response body size to compress.
      # Smaller responses are not worth compressing (overhead > savings).
      min_size: 1024               # Only compress responses larger than 1KB

      # Compression level (1-9). Higher = smaller output but more CPU.
      # 1 = fastest, 6 = balanced (default), 9 = best compression
      level: 6

      # Content types to skip compression (these are already compressed formats).
      # Images, videos, archives, and already-compressed data should be excluded.
      exclude_content_types:
        - image/jpeg
        - image/png
        - image/gif
        - image/webp
        - image/avif
        - video/mp4
        - video/webm
        - audio/mpeg
        - application/zip
        - application/gzip
        - application/x-br

    # Show compression info in response headers
    response_modifiers:
      - headers:
          set:
            X-Compression: "enabled"
            Vary: Accept-Encoding    # Tell caches to vary responses by encoding