Provided by: trafficserver_8.1.1+ds-1.1_amd64 
NAME
remap.config - Traffic Server remap rules configuration file
The remap.config file (by default, located in /usr/local/etc/trafficserver/) contains
mapping rules that Traffic Server uses to perform the following actions:
· Map URL requests for a specific origin server to the appropriate location on Traffic
Server when Traffic Server acts as a reverse proxy for that particular origin server
· Reverse-map server location headers so that when origin servers respond to a request
with a location header that redirects the client to another location, the clients do not
bypass Traffic Server
· Redirect HTTP requests permanently or temporarily without Traffic Server having to
contact any origin servers
Refer to reverse-proxy-and-http-redirects, for information about redirecting HTTP
requests and using reverse proxy.
After you modify the remap.config run the traffic_ctl config reload to apply the changes.
FORMAT
Each line in the remap.config file must contain a mapping rule. Empty lines, or lines
starting with # are ignored. Each line can be broken up into multiple lines for better
readability by using \ as continuation marker.
Traffic Server recognizes three space-delimited fields: type, target, and replacement. The
following list describes the format of each field.
type Enter one of the following:
· map --translates an incoming request URL to the appropriate origin server URL.
· map_with_recv_port --exactly like 'map' except that it uses the port at which the
request was received to perform the mapping instead of the port present in the
request. The regex qualifier can also be used for this type. When present,
'map_with_recv_port' mappings are checked first. If there is a match, then it is
chosen without evaluating the "regular" forward mapping rules.
· map_with_referer -- extended version of 'map', which can be used to activate
"deep linking protection", where target URLs are only accessible when the Referer
header is set to a URL that is allowed to link to the target.
· reverse_map --translates the URL in origin server redirect responses to point to
the Traffic Server.
· redirect --redirects HTTP requests permanently without having to contact the
origin server. Permanent redirects notify the browser of the URL change (by
returning an HTTP status code 301) so that the browser can update bookmarks.
· redirect_temporary --redirects HTTP requests temporarily without having to
contact the origin server. Temporary redirects notify the browser of the URL
change for the current request only (by returning an HTTP status code 307).
target Enter the origin ("from") URL. You can enter up to four components:
scheme://host:port/path_prefix
where scheme is http, https, ws or wss.
replacement
Enter the origin ("from") URL. You can enter up to four components:
scheme://host:port/path_prefix
where scheme is http, https, ws or wss.
PRECEDENCE
Remap rules are not processed top-down, but based on an internal priority. Once these
rules are executed we pick the first match based on configuration file parse order.
1. map_with_recv_port and `regex_map_with_recv_port`
2. map and regex_map and reverse_map
3. redirect and redirect_temporary
4. regex_redirect and regex_redirect_temporary
For each precedence group the rules are checked in two phases. If the first phase fails to
find a match then the second phase is performed against the same group of rules. In the
first phase the rules are checked using the host name of the request. Only rules that
specify a host name can match. If there is no match in that phase, then the rules are
checked again with no host name and only rules without a host will match. The result is
that rules with an explicit host take precedence over rules without.
MATCH-ALL
A map rule with a single / acts as a wildcard, it will match any request. This should be
use with care, and certainly only once at the end of the remap.config file. E.g.
map / http://all.example.com
Examples
The following section shows example mapping rules in the remap.config file.
Reverse Proxy Mapping Rules
The following example shows a map rule that does not specify a path prefix in the target
or replacement:
map http://www.x.com/ http://server.hoster.com/
reverse_map http://server.hoster.com/ http://www.x.com/
This rule results in the following translations:
┌─────────────────────────────────────────────┬──────────────────────────────────────────────────────┐
│Client Request │ Translated Request │
├─────────────────────────────────────────────┼──────────────────────────────────────────────────────┤
│http://www.x.com/Widgets/index.html │ http://server.hoster.com/Widgets/index.html │
├─────────────────────────────────────────────┼──────────────────────────────────────────────────────┤
│http://www.x.com/cgi/form/submit.sh?arg=true │ http://server.hoster.com/cgi/form/submit.sh?arg=true │
└─────────────────────────────────────────────┴──────────────────────────────────────────────────────┘
The following example shows a map rule with path prefixes specified in the target:
map http://www.y.com/marketing/ http://marketing.y.com/
reverse_map http://marketing.y.com/ http://www.y.com/marketing/
map http://www.y.com/sales/ http://sales.y.com/
reverse_map http://sales.y.com/ http://www.y.com/sales/
map http://www.y.com/engineering/ http://engineering.y.com/
reverse_map http://engineering.y.com/ http://www.y.com/engineering/
map http://www.y.com/stuff/ http://info.y.com/
reverse_map http://info.y.com/ http://www.y.com/stuff/
These rules result in the following translations:
┌────────────────────────────────────────────────────────────┬────────────────────────────────────────────────────────┐
└────────────────────────────────────────────────────────────┴────────────────────────────────────────────────────────┘
│http://www.y.com/marketing/projects/manhattan/specs.html │ http://marketing.y.com/projects/manhattan/specs.html │
├────────────────────────────────────────────────────────────┼────────────────────────────────────────────────────────┤
│http://www.y.com/stuff/marketing/projects/boston/specs.html │ http://info.y.com/marketing/projects/boston/specs.html │
├────────────────────────────────────────────────────────────┼────────────────────────────────────────────────────────┤
│http://www.y.com/engineering/marketing/requirements.html │ http://engineering.y.com/marketing/requirements.html │
└────────────────────────────────────────────────────────────┴────────────────────────────────────────────────────────┘
The following example shows that the order of the rules matters:
map http://www.g.com/ http://external.g.com/
reverse_map http://external.g.com/ http://www.g.com/
map http://www.g.com/stuff/ http://stuff.g.com/
reverse_map http://stuff.g.com/ http://www.g.com/stuff/
These rules result in the following translation.
┌─────────────────────────────┬───────────────────────────────────┐
│Client Request │ Translated Request │
├─────────────────────────────┼───────────────────────────────────┤
│http://www.g.com/stuff/a.gif │ http://external.g.com/stuff/a.gif │
└─────────────────────────────┴───────────────────────────────────┘
In the above examples, the second rule is never applied because all URLs that match the
second rule also match the first rule. The first rule takes precedence because it appears
earlier in the remap.config file.
This is different if one rule does not have a host. For example consider these rules using
the Match-All rule:
map / http://127.0.0.1:8001/
map http://example.com/dist_get_user http://127.0.0.1:8001/denied.html
These rules are set up to redirect requests to another local process. Using them will
result in
┌─────────────────────────────────┬───────────────────────────────────┐
│Client Request │ Translated Request │
├─────────────────────────────────┼───────────────────────────────────┤
│http://example.com/a.gif │ http://127.0.0.1:8001/a.gif │
├─────────────────────────────────┼───────────────────────────────────┤
│http://example.com/dist_get_user │ http://127.0.0.1:8001/denied.html │
└─────────────────────────────────┴───────────────────────────────────┘
For the first request the second rule host matches but the path does not and so the second
rule is not selected. The first rule is then matched in the second phase when the rules
are checked without a host value.
The second request is matched by the second rule even though the rules have the same base
precedence. Because the first rule does not have a host it will not match in the first
phase. The second rule does have a host that matches the host in the second request along
with the other parts of the URL and is therefore selected in the first phase.
This will yield the same results if the rules are reversed because the rule selection
happens in different phases making the order irrelevant.
map http://example.com/dist_get_user http://127.0.0.1:8001/denied.html
map / http://127.0.0.1:8001/
The following example shows a mapping with a path prefix specified in the target and
replacement:
map http://www.h.com/a/b/ http://server.h.com/customers/x/y
reverse_map http://server.h.com/customers/x/y/ http://www.h.com/a/b/
This rule results in the following translation.
┌──────────────────────────────────┬────────────────────────────────────────────────┐
│Client Request │ Translated Request │
├──────────────────────────────────┼────────────────────────────────────────────────┤
│http://www.h.com/a/b/c/d/doc.html │ http://server.h.com/customers/x/y/c/d/doc.html │
├──────────────────────────────────┼────────────────────────────────────────────────┤
│http://www.h.com/a/index.html │ Translation fails │
└──────────────────────────────────┴────────────────────────────────────────────────┘
The following example shows reverse-map rules:
map http://www.x.com/ http://server.hoster.com/x/
reverse_map http://server.hoster.com/x/ http://www.x.com/
These rules result in the following translations.
┌─────────────────────────┬────────────────────────────────────┐
│Client Request │ Translated Request │
├─────────────────────────┼────────────────────────────────────┤
│http://www.x.com/Widgets │ http://server.hoster.com/x/Widgets │
└─────────────────────────┴────────────────────────────────────┘
┌─────────────────────────┬─────────────────────────────────────┬───────────────────────────┐
│Client Request │ Origin Server Header │ Translated Request │
├─────────────────────────┼─────────────────────────────────────┼───────────────────────────┤
│http://www.x.com/Widgets │ http://server.hoster.com/x/Widgets/ │ http://www.x.com/Widgets/ │
└─────────────────────────┴─────────────────────────────────────┴───────────────────────────┘
When acting as a reverse proxy for multiple servers, Traffic Server is unable to route to
URLs from older browsers that do not send the Host: header. As a solution, set the
variable proxy.config.header.parse.no_host_url_redirect in the records.config file to the
URL to which Traffic Server will redirect requests without host headers.
Redirect Mapping Rules
The following rule permanently redirects all HTTP requests for www.company.com to
www.company2.com:
redirect http://www.company.com/ http://www.company2.com/
The following rule temporarily redirects all HTTP requests for www.company1.com to
www.company2.com:
redirect_temporary http://www.company1.com/ http://www.company2.com/
REGULAR EXPRESSION (REGEX) REMAP SUPPORT
Regular expressions can be specified in remapping rules, with the limitations below:
· Only the host field can contain a regex; the scheme, port, and other fields cannot. For
path manipulation via regexes, use the admin-plugins-regex-remap.
· The number of capturing subpatterns is limited to 9. This means that $0 through $9 can
be used as subtraction placeholders ($0 will be the entire input string).
· The number of substitutions in the expansion string is limited to 10.
· There is no regex_ equivalent to reverse_remap, so when using regex_map you should make
sure the reverse path is clear by setting (proxy.config.url_remap.pristine_host_hdr)
Examples
regex_map http://x([0-9]+).z.com/ http://real-x$1.z.com/
regex_redirect http://old.(.*).z.com http://new.$1.z.com
MAP_WITH_REFERER
the format of is the following:
map_with_referer client-URL origin-server-URL redirect-URL regex1 [regex2 ...]
'redirect-URL' is a redirection URL specified according to RFC 2616 and can contain
special formatting instructions for run-time modifications of the resulting redirection
URL. All regexes Perl compatible regular expressions, which describes the content of the
"Referer" header which must be verified. In case an actual request does not have "Referer"
header or it does not match with referer regular expression, the HTTP request will be
redirected to 'redirect-URL'.
At least one regular expressions must be specified in order to activate 'deep linking
protection'. There are limitations for the number of referer regular expression strings -
2048. In order to enable the 'deep linking protection' feature in Traffic Server,
configure records.config with:
CONFIG proxy.config.http.referer_filter INT 1
In order to enable run-time formatting for redirect URL, configure:
CONFIG proxy.config.http.referer_format_redirect INT 1
When run-time formatting for redirect-URL was enabled the following format symbols can be
used:
%r - to substitute original "Referer" header string
%f - to substitute client-URL from 'map_with_referer' record
%t - to substitute origin-server-URL from 'map_with_referer' record
%o - to substitute request URL to origin server, which was created a
the result of a mapping operation
Note: There is a special referer type "~*" that can be used in order to specify that the
Referer header is optional in the request. If "~*" referer was used in map_with_referer
mapping, only requests with Referer header will be verified for validity. If the "~"
symbol was specified before referer regular expression, it means that the request with a
matching referer header will be redirected to redirectURL. It can be used to create a
so-called negative referer list. If "*" was used as a referer regular expression - all
referers are allowed. Various combinations of "*" and "~" in a referer list can be used
to create different filtering rules.
map_with_referer Examples
map_with_referer http://y.foo.bar.com/x/yy/ http://foo.bar.com/x/yy/ http://games.bar.com/new_games .*\.bar\.com www.bar-friends.com
Explanation: Referer header must be in the request, only ".*.bar.com" and
"www.bar-friends.com" are allowed.
map_with_referer http://y.foo.bar.com/x/yy/ http://foo.bar.com/x/yy/ http://games.bar.com/new_games * ~.*\.evil\.com
Explanation: Referer header must be in the request but all referers are allowed except
".*.evil.com".
map_with_referer http://y.foo.bar.com/x/yy/ http://foo.bar.com/x/yy/ http://games.bar.com/error ~* * ~.*\.evil\.com
Explanation: Referer header is optional. However, if Referer header exists, only request
from ".*.evil.com" will be redirected to redirect-URL.
PLUGIN CHAINING
Plugins can be configured to be evaluated in a specific order, passing the results from
one in to the next (unless a plugin returns 0, then the "chain" is broken).
Examples
map http://url/path http://url/path \
@plugin=/etc/traffic_server/config/plugins/plugin1.so @pparam=1 @pparam=2 \
@plugin=/etc/traffic_server/config/plugins/plugin2.so @pparam=3
will pass "1" and "2" to plugin1.so and "3" to plugin2.so.
This will pass "1" and "2" to plugin1.so and "3" to plugin2.so
ACL FILTERS
Acl filters can be created to control access of specific remap lines. The markup is very
similar to that of ip_allow.config, with slight changes to accommodate remap markup
Examples
map http://foo.example.com/neverpost http://foo.example.com/neverpost @action=deny @method=post
map http://foo.example.com/onlypost http://foo.example.com/onlypost @action=allow @method=post
map http://foo.example.com/ http://foo.example.com/ @action=deny @src_ip=1.2.3.4
map http://foo.example.com/ http://foo.example.com/ @action=allow @src_ip=127.0.0.1
map http://foo.example.com/ http://foo.example.com/ @action=allow @src_ip=10.5.2.1 @in_ip=72.209.23.4
map http://foo.example.com/ http://foo.example.com/ @action=allow @src_ip=127.0.0.1 @method=post @method=get @method=head
Note that these Acl filters will return a 403 response if the resource is restricted.
The difference between @src_ip and @in_ip is that the @src_ip is the client ip and the
in_ip is the ip address the client is connecting to (the incoming address).
NAMED FILTERS
Named filters can be created and applied to blocks of mappings using the .definefilter,
.activatefilter, and .deactivatefilter directives. Named filters must be defined using
.definefilter before being used. Once defined, .activatefilter can used to activate a
filter for all mappings that follow until deactivated with .deactivatefilter.
The @internal operator can be used to filter on whether a request is generated by Traffic
Server itself, usually by a plugin. This operator is helpful for remapping internal
requests without allowing access to external users. By default both internal and external
requests are allowed.
Examples
.definefilter disable_delete_purge @action=deny @method=delete @method=purge
.definefilter local_only @action=allow @src_ip=192.168.0.1-192.168.0.254 @src_ip=10.0.0.1-10.0.0.254
.activatefilter disable_delete_purge
map http://foo.example.com/ http://bar.example.com/
.activatefilter local_only
map http://www.example.com/admin http://internal.example.com/admin
.deactivatefilter local_only
map http://www.example.com/ http://internal.example.com/
map http://auth.example.com/ http://auth.internal.example.com/ @action=allow @internal
The filter disable_delete_purge will be applied to all of the mapping rules. (It is
activated before any mappings and is never deactivated.) The filter local_only will only
be applied to the second mapping.
INCLUDING ADDITIONAL REMAP FILES
The .include directive allows mapping rules to be spread across multiple files. The
argument to the .include directive is a list of file names to be parsed for additional
mapping rules. Unless the names are absolute paths, they are resolved relative to the
Traffic Server configuration directory.
The effect of the .include directive is as if the contents of the listed files is included
in the parent and parsing restarted at the point of inclusion. This means that and filters
named in the included files are global in scope, and that additional .include directives
are allowed.
NOTE:
Included remap files are not currently tracked by the configuration subsystem. Changes
to included remap files will not be noticed by online configuration changes applied by
traffic_ctl config reload unless remap.config has also changed.
Examples
In this example, a top-level remap.config file simply references additional mapping rules
files
.include filters.config
.include one.example.com.config two.example.com.config
The file filters.config contains
.definefilter deny_purge @action=deny @method=purge
.definefilter allow_purge @action=allow @method=purge
The file one.example.com.config contains:
.activatefilter deny_purge
map http://one.example.com http://origin-one.example.com
.deactivatefilter deny_purge
The file two.example.com.config contains:
.activatefilter allow_purge
map http://two.example.com http://origin-two.example.com
.deactivatefilter dallowpurge
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