Comment configurer HAProxy pour plusieurs certificats SSL ?

Je dois configurer HAProxy avec deux certificats SSL différents.

1. www.example.com
2. api.example.com

J'ai appris par un post sur serverfault ( Configurer plusieurs certificats SSL dans Haproxy ) comment utiliser deux certificats, mais le serveur continue d'utiliser le premier certificat mentionné pour les deux domaines.

Config :

frontend apache-https
    bind 192.168.56.150:443 ssl crt /certs/crt1.pem crt /certs/cert2.pem
    reqadd X-Forwarded-Proto:\ https
    default_backend apache-http

backend apache-http
    redirect scheme https if { hdr(Host) -i www.example.com } !{ ssl_fc }
    redirect scheme https if { hdr(Host) -i api.example.com } !{ ssl_fc }
    ...

Comment indiquer à HAProxy quel certificat utiliser en fonction de l'URL ?

Configuration complète :

global
    log /dev/log    local0
    log /dev/log    local1 notice
    chroot /var/lib/haproxy
    stats socket /run/haproxy/admin.sock mode 660 level admin
    stats timeout 30s
    user haproxy
    group haproxy
    daemon

    # Default SSL material locations
    ca-base /etc/ssl/certs
    crt-base /etc/ssl/private

    ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
    ssl-default-bind-options no-sslv3
    tune.ssl.default-dh-param 2048 // better with 2048 but more processor intensive

defaults
        log     global
        mode    http
        option tcplog
        option  dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000

frontend apache-http
        bind 0.0.0.0:80
        mode http
        option http-server-close                # needed for forwardfor
        option forwardfor                       # forward IP Address of client
        reqadd X-Forwarded-Proto:\ http
        default_backend apache-http
        stats enable

frontend apache-https
        bind 0.0.0.0:443 ssl crt cer1.pem cert2.pem
        reqadd X-Forwarded-Proto:\ https
        default_backend apache-http

backend apache-http
        redirect scheme https if { hdr(Host) -i db.example.com } !{ ssl_fc }
        redirect scheme https if { hdr(Host) -i api2.example.com } !{ ssl_fc }
        balance roundrobin
        cookie SERVERID insert indirect nocache
        server www-1 10.0.0.101:80 cookie S1 check
        server www-2 10.0.0.102:80 cookie S2 check
        server www-3 10.0.0.103:80 cookie S3 check