Thanks for the help Jens!
-- Tom Braarup Senior Linux Administrator IT Infrastruktur Platform - Digital Udvikling og Teknologi ________________________________ -----Original Message----- From: Jens Wahnes <[email protected]> To: [email protected] Subject: Re: How do I use "ltrim"? Date: 08/25/2025 02:21:18 PM Tom Braarup wrote: > How do I use "ltrim" > (https://www.haproxy.com/documentation/haproxy-configuration-manual/latest/#7.3.1-ltrim) > ? > > Trying to do a redirect short.com/123456 to example.com/id123456 > http-request redirect locationhttps://example.com/id%[path,ltrim(/)] if { > req.hdr(host) -i short.com && path_reg -i ^/\d+$ } There are two things I see in your config that are not along the lines Haproxy configuration needs to be written. 1) You seem to get bitten by the way the config parser works and need to use quoting. Otherwise, the comma you are using to produce the "location" argument will not be interpreted correctly. See the explanations at https://www.haproxy.com/documentation/haproxy-configuration-manual/latest/#2.2 2) Haproxy's configuration language does not allow logical operators like '&&' to form complex conditions (and, while we're at it, not parentheses). You'll need to cope with the use of the implicit "or" (within one ACL, more so for named ACLs), the implicit "and" (in between single ACLs) and the "or" keyword (outside of individual conditions). See https://www.haproxy.com/documentation/haproxy-configuration-manual/latest/#7.2 (This really has to do with how you want to look at it, but from the formal computer science perspective, to construct a valid Haproxy configuration, you need to express yourself in "conjunctive normal form".) Putting aside theoretical thoughts, as far as I understand what you're trying to do, you could write the above line like this: http-request redirect location "https://example.com/id%[path,ltrim(/)]" if { req.hdr(host) -i short.com } { path_reg -i ^/\d+$ } This is at least valid Haproxy config syntax, although I'm not 100 percent sure this does what you intend to do. Another way to tackle a substitution like that would be to use "regsub", as you were using a regular expression already. But then, with regsub and backreferences like "\1", you will really need to look into the section about quoting in the manual, as it gets a bit complicated at that point. Good luck, Jens
