Unexpected/wrong/undocumented behavior when using regex_remap plugin

[wederbrand]

According to the documentation defining something like:
map http://a.com http://b.com @plugin=regex_remap.so @pparam=maps.reg
will redirect to http://b.com if none if the rules in maps.reg matches.

However, I've seen that if we instead of http://b.com/ writes http://b.com/default the word default gets prepended to the string being matched. I would expect the "fall through url" to be totally ignored before matching has been done.

[mlibbey]

Can you post the content of maps.reg?

[wederbrand]

Sure, it's very simple as I'm just trying to learn ATS. Basically I have ATS running on port 8080 and then I have authentication service running on 8081 and my backend service on 8082

^/home/(.*)/climate http://xxx.xxx.xxx.xxx:8082/climate/$1
^/home/(.*)/light http://xxx.xxx.xxx.xxx:8082/light/$1

in remap.config I have this (and nothing else)

regex_map http://.*:8080/ http://xxx.xxx.xxx.xxx:8082/<adding something here breaks it> \
@plugin=authproxy.so \
 @pparam=--auth-transform=redirect \
 @pparam=--auth-host=xxx.xxx.xxx.xxx \
 @pparam=--auth-port=8081 \
@plugin=regex_remap.so \
 @pparam=maps.reg \
 @pparam=profile

# authentication service needs to be added without authentication ...
map http://xxx.xxx.xxx.xxx:8081/ http://xxx.xxx.xxx.xxx:8081/

[takkitano]

I think it’s because regex_remap plugin use post remapped path to check regex remap rule.

In my environment,
when trafficserver get http request from client,
first, trafficserver execute first remap plugin’s TSRemapDoRemap function. (in the above configuration, authproxy plugin’s TSRemapDoRemap.)
Next, trafficserver execute remap operetaion.
And finally, trafficserver execute regex_remap plugin’s TSRemapDoRemap function.

Then regex_remap plugin get post remapped url in the following lines.
https://github.com/apache/trafficserver/blob/master/plugins/regex_remap/regex_remap.cc#L97-L102

I was faced the same problem.
I use trafficserver-7.1.4.

In following setting, trafficserver should forward the request from “http://before-remap.com/” to “http://after-remap.com/index.html”.
But my trafficserver forward the request from “http://before-remap.com/” to “http://after-remap.com/no-regex/“.

• remap.config

map http://before-remap.com/ http://after-remap.com/no-regex/ @plugin=conf_remap.so @pparam=proxy.config.url_remap.pristine_host_hdr=0 @plugin=regex_remap.so @pparam=/opt/trafficserver-7.1.4/etc/trafficserver/test.reg

• /opt/trafficserver-7.1.4/etc/trafficserver/test.reg (regex_remap setting)

^/$     http://after-remap.com/index.html

Debug log of “regex_remap” tag is follow.
I think regex_remap plugin use the post remapped path to check whether the path match with regex remap rule or not.

(regex_remap) Target match string is `/no-regex/'

[bryancall]

If this is still an issue please reopen.

[gtenev]

This issue should have been fixed by PR #4964 which implemented what was agreed on the dev mailing list - email thread "[PROPOSAL] Rewrite url after running all remap plugins" which resulted in a new proposal to "rewrite url before all remap plugins". Please reopen if any problems or concerns!