remap.config¶
The remap.config file 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_line -x to apply the changes. When you apply the changes to one node in a cluster, Traffic Server automatically applies the changes to all other nodes in the cluster.
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.
- 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.
- replacement
Enter the origin (“from”) URL. You can enter up to four components:
scheme://host:port/path_prefix
where scheme can be http or https.
Precedence¶
Remap rules are not processed top-down, but based on an internal priority
- map and reverse_map
- regex_map
- redirect and redirect_temporary
- regex_redirect and regex_redirect_temporary
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:
| Client Request | Translated Request |
|---|---|
| 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.
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 regex_remap plugin.
- 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_remap 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
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
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.
Examples¶
.definefilter disable_delete_purge @action=deny @method=delete @method=purge
.definefilter internal_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 internal_only
map http://www.example.com/admin http://internal.example.com/admin
.deactivatefilter internal_only
map http://www.example.com/ http://internal.example.com/
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 internal_only will only be applied to the second mapping.