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cherouvim
Asked: 2017-06-17 02:01:38 +0800 CST

how to redirect on the requested scheme (http or https)

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I'm redirecting to some domain based on an acl condition but I want the user to end up on either http or https depending on the scheme/protocol of their request. I've managed to do that with the 2 lines shown bellow, but I'd like to convert them to just 1 line:

http-request redirect code 301 location http://www.example.com%[url] if acl_whatever !{ ssl_fc }
http-request redirect code 301 location https://www.example.com%[url] if acl_whatever { ssl_fc }

Ideally I'd like to redirect to something like %[scheme]://www.example.com%[url] but %[scheme] does not exist.

Is there a variable or function which can return http or https so I do not have to repeat the rule twice? Maybe by somehow setting a variable containing the scheme or maybe by using the value of %[ssl_fc] which is 0 or 1?

haproxy

2 Answers

  1. Best Answer

    You can do this using http-request set-var and %[var(name)]:

    http-request set-var(req.scheme) str(https) if { ssl_fc }
http-request set-var(req.scheme) str(http) if ! { ssl_fc }
http-request redirect code 301 location %[var(req.scheme)]://www.example.com%[url] if acl_whatever
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  2. As an addition:

    If the request schema is needed in the response, txn scope must be used instead of req.

    For example:

    frontend http_awesome_frontend


http-request set-var(txn.scheme) str(https) if { ssl_fc }
http-request set-var(txn.scheme) str(http) if !{ ssl_fc }


# Outer frontend response:

http-response add-header X-Original-Proto %[var(txn.scheme)]

    All variables are scoped, meaning they can only be accessed within the same or larger scope. When you set a variable, you prefix its names with a scope. The scope can be any of the following:

    • proc: variable is available during all phases
    • sess: variable is available during a client's entire TCP session
    • txn: variable is available during an entire HTTP request-response transaction
    • req: variable is available during the HTTP request phase only
    • res: variable is available during the HTTP response phase only

    Sources: HA Proxy Documentation

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