How to make haproxy send http 404 when no acl get matched

Help!
2

You can create a new backend without any server (which will cause a 503 error), and use a custom 503 errorfile for this, generating the 404 error (custom error files include HTTP response and header, not just payload).

For example:

frontend www-in
 default_backend generate_404

backend generate_404
 errorfile 503 /etc/haproxy/generate_404.http

Than create that file as per errorfile docs.

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