🔗 Using eCAP for GZip/DEFLATE support with Squid

by Yuri Voinov

🔗 Outline

Since Squid does not support runtime content compression with GZip/DEFLATE, we will be used existing eCAP support and re-worked and improved adapter from here.

Note: Since the original author has long abandoned adapter use re-worked and improved version.

🔗 Usage

This configuration is very useful to reduce internal traffic and load to downstream interfaces.

🔗 Build eCAP library

We are using v1.0.0 or v1.0.1 for Squid 3.5.x/4.x.x downloads link. Due to API changes, adapters no more compatible with older libecap.

Build and install library accordingly your Squid 32-bit or 64-bit versions:

## 32-bit GCC
./configure 'CXXFLAGS=-O2 -m32 -pipe' 'CFLAGS=-O2 -m32 -pipe'

## 64-bit GCC
./configure 'CXXFLAGS=-O2 -m64 -pipe' 'CFLAGS=-O2 -m64 -pipe'

gmake
gmake install-strip

Then rebuild your Squid with –enable-ecap configure option. To do that you may need to add PKG_CONFIG_PATH to your configure options:

./configure '--enable-ecap' 'PKG_CONFIG_PATH=/usr/local/lib/pkgconfig'

PKG_CONFIG_PATH pointed to libecap pkgconfig file.

🔗 Build squid-ecap-gzip

./configure 'CXXFLAGS=-m32' 'LDFLAGS=-L/usr/local/lib'

or

./configure 'CXXFLAGS=-m64' 'LDFLAGS=-L/usr/local/lib'

make
make install-strip

Note: It is important to choose identical 32 or 64 bit (like your Squid) build mode for eCAP library and squid-gzip-ecap.

Note: LDFLAGS should point on libecap directory.

🔗 Adapter configuration

Adapter versions starting 1.5.0 configures via ecap_service arguments in squid.conf.

Supported configuration parameters:

maxsize (default 16777216 bytes, i.e. 16 Mb) - maximum compressed file size
level (default is 6, valid range 0-9) - gzip/deflate global compression level
errlogname (default path/filename is /var/log/ecap_gzip_err.log)        - arbitrary error log name.
complogname (default path/filename is /var/log/ecap_gzip_comp.log)      - arbitrary compression log name.
errlog (default is 0, default path/filename is /var/log/ecap_gzip_err.log)      - error log
complog (default is 0, default path/filename is /var/log/ecap_gzip_comp.log)    - compression log

Note: errlogname/complogname should be specify with full path and file name. Directory(-ies) should have write permission for proxy. If file(s) exists - it will appends. It not exists - will be created.

Adapter logging disabled by default. To enable error log specify errlog=1. To enable compression log specify complog=1. Proxy must have permissions to write.

Note: When configuration parameters has any error in specifications, adapter starts with defaults. If error log exists, diagnostics message will be write.

🔗 Squid Configuration File

Paste the configuration file like this:

ecap_enable on
acl gzipmimes rep_mime_type -i "/usr/local/squid/etc/acl.gzipmimes"
loadable_modules /usr/local/lib/ecap_adapter_gzip.so
ecap_service gzip_service respmod_precache ecap://www.thecacheworks.com/ecap_gzip_deflate [maxsize=16777216] [level=6] [errlog=0] [complog=0] bypass=off
adaptation_access gzip_service allow gzipmimes

and acl.gzipmimes contents:

# Note: single "/" produces error in simulators,
#       but works in squid's regex
^application/atom+xml
^application/dash+xml
^application/javascript
^application/json
^application/ld+json
^application/manifest+json
^application/opensearchdescription+xml
^application/rdf+xml
^application/rss+xml
^application/schema+json
^application/soap+xml
^application/vnd.apple.installer+xml
^application/vnd.apple.mpegurl
^application/vnd.geo+json
^application/vnd.google-earth.kml+xml
^application/vnd.mozilla.xul+xml
^application/x-apple-plist
^application/x-javascript
^application/x-mpegurl
^application/x-ns-proxy-autoconfig
^application/x-protobuffer
^application/x-web-app-manifest+json
^application/x-www-form-urlencoded
^application/xop+xml
^application/xhtml+xml
^application/xml
^application/x-yaml
^application/x-cdf
^application/txt
^application/x-sdch-dictionary
^application/x-steam-manifest
^audio/x-mpegurl
^image/svg+xml
^image/x-icon
^text/.*
^video/abst
^video/vnd.mpeg.dash.mpd

Finally, restart your Squid and enjoy.

🔗 Notes

Due to performance reasons, all mime checks executes only once outside adapter, at proxy level. So, be careful when choose what mime types will be pass into adapter.

Also, HTTP/200 status now checks directly inside adapter. So, this rule:

acl HTTP_STATUS_OK http_status 200
adaptation_access gzip_service allow HTTP_STATUS_OK

is no longer required.

Also be careful with text/plain mime-type. For some reasons you may be required to remove it from acl, because of sometimes plain text files can be inadequately big and and can overload the CPU during decompression. In this case specify “maxsize” which fit you requirements.

Note: Adapter requires c++11 - compatible C++ compiler to build.

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⚠️ Disclaimer: Any example presented here is provided "as-is" with no support
or guarantee of suitability. If you have any further questions about
these examples please email the squid-users mailing list.

Categories: ConfigExample

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