Hello list, I need to add a Vary header with Origin value in order to properly
configure a Cors Allow Origin with dynamic content. This works well provided
that my backend doesn’t need to configure another value to the Vary header. I
observed that if I configure set-header, this will overwrite the header
provided by the app; if I configure add-header, this will create another header
instead of concatenate the values into a single one, as suggested here[1] and
here[2].
At this moment these are the best configurations that I managed to build:
A)
http-response set-header vary %[res.hdr(vary)],origin if { res.hdr(vary) -m
found }
http-response set-header vary origin if ! { res.hdr(vary) -m found }
B)
http-response replace-header vary (.*) \1,origin if { res.hdr(vary) -m found }
http-response set-header vary origin if ! { res.hdr(vary) -m found }
Option A would remove some previous duplicated vary header, preserving just one
of them; option B would add origin on all duplicated headers. And all of them
seems to be more verbose than needed.
It seems that I’m missing some haproxy config here. Is there a better or
suggested way to add a new value to an existing header without adding a new
whole header line?
~jm
[1] https://datatracker.ietf.org/doc/html/rfc7230#section-3.2.2
[2] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary
