Reference manual for squid's configuraiton directives
This is the documentation for the Squid configuration file.
This documentation can also be found online at:
http://www.squid-cache.org/Doc/config/
You may wish to look at the Squid home page and wiki for the
FAQ and other documentation:
http://www.squid-cache.org/
https://wiki.squid-cache.org/SquidFaq
https://wiki.squid-cache.org/ConfigExamples
This documentation shows what the defaults for various directives
happen to be. If you don't need to change the default, you should
leave the line out of your squid.conf in most cases.
In some cases "none" refers to no default setting at all,
while in other cases it refers to the value of the option
- the comments for that keyword indicate if this is the case.
Include takes a list of files to include. Quoting and wildcards are supported.
For example,
include /path/to/included/file/squid.acl.config
Includes can be nested up to a hard-coded depth of 16 levels. This arbitrary restriction is to prevent recursive include references from causing Squid entering an infinite loop whilst trying to load configuration files.
Values with byte units
Squid accepts size units on some size related directives. All
such directives are documented with a default value displaying
a unit.
Units accepted by Squid are:
bytes - byte
KB - Kilobyte (2^10, 1'024 bytes)
MB - Megabyte (2^20, 1'048'576 bytes)
GB - Gigabyte (2^30, 1'073'741'824 bytes)
Squid does not yet support KiB, MiB, and GiB unit names.
Values with time units
Time-related directives marked with either "time-units" or
"time-units-small" accept a time unit. The supported time units are:
nanosecond (time-units-small only)
microsecond (time-units-small only)
millisecond
second
minute
hour
day
week
fortnight
month - 30 days
year - 31557790080 milliseconds (just over 365 days)
decade
Values with spaces, quotes, and other special characters
Squid supports directive parameters with spaces, quotes, and other
special characters. Surround such parameters with "double quotes". Use
the configuration_includes_quoted_values directive to enable or
disable that support.
Squid supports reading configuration option parameters from external
files using the syntax:
parameters("/path/filename")
For example:
acl allowlist dstdomain parameters("/etc/squid/allowlist.txt")
Conditional configuration
If-statements can be used to make configuration directives
depend on conditions:
if <CONDITION>
... regular configuration directives ...
[else
... regular configuration directives ...]
endif
The else part is optional. The keywords "if", "else", and "endif"
must be typed on their own lines, as if they were regular
configuration directives.
NOTE: An else-if condition is not supported.
These individual conditions types are supported:
true
Always evaluates to true.
false
Always evaluates to false.
<integer> = <integer>
Equality comparison of two integer numbers.
SMP-Related Macros
The following SMP-related preprocessor macros can be used.
${process_name} expands to the current Squid process "name"
(e.g., squid1, squid2, or cache1).
${process_number} expands to the current Squid process
identifier, which is an integer number (e.g., 1, 2, 3) unique
across all Squid processes of the current service instance.
${service_name} expands into the current Squid service instance
name identifier which is provided by -n on the command line.
Logformat Macros
Logformat macros can be used in many places outside of the logformat
directive. In theory, all of the logformat codes can be used as %macros,
where they are supported. In practice, a %macro expands as a dash (-) when
the transaction does not yet have enough information and a value is needed.
There is no definitive list of what tokens are available at the various
stages of the transaction.
And some information may already be available to Squid but not yet
committed where the macro expansion code can access it (report
such instances!). The macro will be expanded into a single dash
('-') in such cases. Not all macros have been tested.
Also see “pconn_timeout” in the TIMEOUTS section