.. _config_http_filters_compressor: Compressor ========== Compressor is an HTTP filter which enables Envoy to compress dispatched data from an upstream service upon client request. Compression is useful in situations when bandwidth is scarce and large payloads can be effectively compressed at the expense of higher CPU load or offloading it to a compression accelerator. .. note:: This filter deprecates the :ref:`HTTP Gzip filter `. Configuration ------------- * :ref:`v3 API reference ` * This filter should be configured with the name *envoy.filters.http.compressor*. How it works ------------ When compressor filter is enabled, request and response headers are inspected to determine whether or not the content should be compressed. The content is compressed and then sent to the client with the appropriate headers, if response and request allow. Currently the filter supports :ref:`gzip compression ` only. Other compression libraries can be supported as extensions. An example configuration of the filter may look like the following: .. code-block:: yaml http_filters: - name: envoy.filters.http.compressor typed_config: "@type": type.googleapis.com/envoy.extensions.filters.http.compressor.v3.Compressor disable_on_etag_header: true content_length: 100 content_type: - text/html - application/json compressor_library: name: text_optimized typed_config: "@type": type.googleapis.com/envoy.extensions.compression.gzip.compressor.v3.Gzip memory_level: 3 window_bits: 10 compression_level: best_compression compression_strategy: default_strategy By *default* compression will be *skipped* when: - A request does NOT contain *accept-encoding* header. - A request includes *accept-encoding* header, but it does not contain "gzip" or "\*". - A request includes *accept-encoding* with "gzip" or "\*" with the weight "q=0". Note that the "gzip" will have a higher weight then "\*". For example, if *accept-encoding* is "gzip;q=0,\*;q=1", the filter will not compress. But if the header is set to "\*;q=0,gzip;q=1", the filter will compress. - A request whose *accept-encoding* header includes any encoding type with a higher weight than "gzip"'s given the corresponding compression filter is present in the chain. - A response contains a *content-encoding* header. - A response contains a *cache-control* header whose value includes "no-transform". - A response contains a *transfer-encoding* header whose value includes "gzip". - A response does not contain a *content-type* value that matches one of the selected mime-types, which default to *application/javascript*, *application/json*, *application/xhtml+xml*, *image/svg+xml*, *text/css*, *text/html*, *text/plain*, *text/xml*. - Neither *content-length* nor *transfer-encoding* headers are present in the response. - Response size is smaller than 30 bytes (only applicable when *transfer-encoding* is not chunked). Please note that in case the filter is configured to use a compression library extension other than gzip it looks for content encoding in the *accept-encoding* header provided by the extension. When compression is *applied*: - The *content-length* is removed from response headers. - Response headers contain "*transfer-encoding: chunked*" and do not contain "*content-encoding*" header. - The "*vary: accept-encoding*" header is inserted on every response. .. _compressor-statistics: Statistics ---------- Every configured Compressor filter has statistics rooted at .compressor...* with the following: .. csv-table:: :header: Name, Type, Description :widths: 1, 1, 2 compressed, Counter, Number of requests compressed. not_compressed, Counter, Number of requests not compressed. no_accept_header, Counter, Number of requests with no accept header sent. header_identity, Counter, Number of requests sent with "identity" set as the *accept-encoding*. header_compressor_used, Counter, Number of requests sent with "gzip" set as the *accept-encoding*. header_compressor_overshadowed, Counter, Number of requests skipped by this filter instance because they were handled by another filter in the same filter chain. header_wildcard, Counter, Number of requests sent with "\*" set as the *accept-encoding*. header_not_valid, Counter, Number of requests sent with a not valid *accept-encoding* header (aka "q=0" or an unsupported encoding type). total_uncompressed_bytes, Counter, The total uncompressed bytes of all the requests that were marked for compression. total_compressed_bytes, Counter, The total compressed bytes of all the requests that were marked for compression. content_length_too_small, Counter, Number of requests that accepted gzip encoding but did not compress because the payload was too small. not_compressed_etag, Counter, Number of requests that were not compressed due to the etag header. *disable_on_etag_header* must be turned on for this to happen.