parent.config

The parent.config file identifies the HTTP parent proxies used in an HTTP cache hierarchy. Use this file to perform the following configuration:

Set up parent cache hierarchies, with multiple parents and parent failover

Configure selected URL requests to bypass parent proxies

Rules are applied from the list top-down; the first match is applied. Bypass rules are usually placed above parent proxy designation rules.

Content Gateway uses the parent.config file only when the HTTP parent caching option is enabled. See Configuring Content Gateway to use an HTTP parent cache.


	Important After you modify this file, run the following command to apply the changes: /opt/WCG/bin/content_line -x When you apply the changes to a node in a cluster, Content Gateway applies the changes to all nodes in the cluster.

Format

Each line in the parent.config file must contain a parent caching rule. Content Gateway recognizes three space-delimited tags:

primary_destination=value secondary_specifier=value action=value

The following table lists the possible primary destinations and their allowed values.


Primary Destination	Allowed Value
dest_domain	A requested domain name
dest_host	A requested hostname
dest_ip	A requested IP address or range of IP addresses separated by a dash (-).
url_regex	A regular expression to be found in a URL. See Specifying URL regular expressions (url_regex) for information on using regular expressions.

Secondary specifiers are optional in the parent.config file. The following table lists the possible secondary specifiers and their allowed values.

Secondary Specifier

Allowed Value

time

A time range, such as 08:00-14:00, during which the parent cache is used to serve requests

prefix

A prefix in the path part of a URL

suffix

A file suffix in the URL

A request URL protocol; one of the following:

HTTP

FTP

method

A request URL method; one of the following:

A request header User-Agent value.

Takes a regular expression that is applied to the user-agent string. SeeSpecifying URL regular expressions (url_regex) for information on using regular expressions.

The following table lists the possible actions and their allowed values.

Action

Allowed Value

parent

An ordered list of parent servers. If the request cannot be handled by the last parent server in the list, it will be routed to the origin server. You can specify either a hostname or an IP address. You must specify the port number.

round_robin

One of the following values:

true - Content Gateway goes through the parent cache list in a round-robin based on client IP address.

strict - Content Gateway machines serve requests strictly in turn. For example, machine proxy1 serves the first request, proxy2 serves the second request, and so on.

false - round-robin selection does not occur.

go_direct

One of the following values:

true - requests bypass parent hierarchies and go directly to the origin server.

false - requests do not bypass parent hierarchies.

Examples

The following rule configures a parent cache hierarchy consisting of Content Gateway (which is the child) and two parents, p1.x.com and p2.x.com. The proxy forwards the requests it cannot serve to the parent servers p1.x.com and p2.x.com in a round-robin fashion because round_robin=true.

dest_domain=. method=get parent="p1.x.com:8080; p2.y.com:8080" round_robin=true

The following rule configures Content Gateway to route all requests containing the regular expression politics and the path /viewpoint directly to the origin server (bypassing any parent hierarchies):

url_regex=politics prefix=/viewpoint go_direct=true

The following rule is a typical destination bypass rule:

dest_domain=example.com go_direct=true


	Important Every line in the parent.config file must contain either a parent= or go_direct= directive. A bypass rule that includes parent= and go_direct=true, causes the specified dest_domain to be sent to the parent while all other domains are bypassed (the opposite of the usual intended action).