flask-compress

• fix possible RuntimeError when applying compression to a streaming endpoint
• no longer apply make_conditional to streaming responses, as it had the effect of buffering the entire response, which defeats the purpose of streaming responses, unless the request.endpoint is in a new COMPRESS_STREAMING_ENDPOINT_CONDITIONAL config option, which defaults to ["static"]

As serving static content with Flask is using streaming responses, we wanted to preserve the correct handling of conditional requests (i.e. 304 Not Modified responses) for static content, while avoiding buffering the entire response when compressing streaming responses for other endpoints

• compressing streaming responses is now supported:
  • the previous behavior was:
    • if COMPRESS_STREAMS was True (the default), streaming responses were compressed in 1 sitting using response.get_data(), meaning streaming responses were compressed but not streamed
    • if COMPRESS_STREAMS was False, streaming responses were not compressed at all
  • the new behavior is:
    • if COMPRESS_STREAMS is True, streaming responses are compressed chunk-by-chunk using response.iter_encoded(), which means that streaming responses are compressed and streamed
    • if COMPRESS_STREAMS is False, streaming responses are not compressed at all, as before.
  • we have a new COMPRESS_ALGORITHM_STREAMING config option to specify the compression algorithm to use for streaming responses, which defaults to ["zstd", "br", "deflate"], as "gzip" is not suitable for streaming compression.
  • ⚠️ serving static content with Flask is actually using streaming responses, so if you enable streaming compression, static content will be compressed chunk-by-chunk as well, which may not be what you want.

• the new COMPRESS_EVALUATE_CONDITIONAL_REQUEST config option is now True by default

• Use backports.zstd instead of pyzstd, #63 by @alexprengere
• Add new behaviours to improve Etag compatibility, #67, by @jlopex
  • weak etags are no longer modified by flask-compress
  • add new COMPRESS_EVALUATE_CONDITIONAL_REQUEST config option to call response.make_conditional(request) after compression, this ensures that 304 Not Modified responses are correctly generated when the client sends conditional requests with If-None-Match (defaults to False)

• Support, and test against, Python 3.14, see #61 by @kurtmckee
• Migrate from zstandard to pyzstd, which is now included in the Python 3.14 standard library, also part of #61
• Restore flask_compress.DictCache() that is needed to configure Flask-Compress with caching, without relying on Flask-Caching

• Add support for Python 3.13 in tox and classifiers
• Expand mimetype defaults, see #57
• Minor performance improvements, cache the algorithm selection logic

• Drop support for Python 3.8 and lower, see #46
• Fix cache pollution caused by caching compression results for different compression algorithms, see #53

• add ZStandard compression

• switch to using python-zstandard

---

Co-authored-by: Tristan Moreno tristan.moreno@orange.com

• Add text/javascript mimetype. See #41
• Use brotlicffi for PyPy

• Re-enable compression for streaming, but hide it behind a new option COMPRESS_STREAMS that defaults to True. See #36

• Disable compression when response is streamed, see #31

• When compression is enabled, accept-encoding is always added to the Vary header, fixes #28

• Automate the release process with GitHub Actions
• Use setuptools_scm to manage package versions
• The layout is now an actual package rather than a single module
• Clean up unused files

• Add support for the identity value in accept-encoding, fixes #19

• Support ETag header as defined in RFC7232 #17
• Implement per-view compression #14

• The following parameters to control Brotli compression are now available: #10
  • COMPRESS_BR_MODE
  • COMPRESS_BR_LEVEL
  • COMPRESS_BR_WINDOW
  • COMPRESS_BR_BLOCK
• Add deflate support, with COMPRESS_DEFLATE_LEVEL to control compression level (default is -1) #8
• The default quality level for Brotli is now 4, which provides compression comparable to gzip at the default setting, while reducing the time required versus the Brotli default of 11

• Support for multiple compression algorithms and quality factors #7
• Modified default compression settings to use Brotli when available before gzip

• Add Brotli support #1