HAProxy configuration to deploy PSGI application

haproxy.conf

#
# application entry points
#   https://www.example.com/ (production)
#   https://demo.example.com/ (demo/lite production)
#   https://devel.example.com/ (development)
#
# static content served by nginx server
#   http://app-be1.example.net:4xxx/
#   http://app-be2.example.net:4xxx/
#
# dynamic content served by PSGI server
#   http://app-be1.example.net:3xxx/
#   http://app-be2.example.net:3xxx/
#

global
    nbproc  1
    maxconn 8192
    user    nobody
    group   nobody
    log     /var/run/log local0
    daemon
    # enable compression (haproxy v1.5-dev13 and above required)
    tune.comp.maxlevel 5
    spread-checks 5

defaults
    log     global
    option  httpclose
    option  httplog
    option  dontlognull
    option  forwardfor 
    option  abortonclose
    option  redispatch
    mode    http
    balance roundrobin
    retries 3
    timeout connect         5s
    timeout server          30s
    timeout client          30s
    timeout http-keep-alive 200m
    # enable compression (haproxy v1.5-dev13 and above required)
    compression algo gzip
    compression type text/html application/javascript text/css application/x-javascript text/javascript

userlist dev-ops
    user op1 insecure-password hoochi-mama1
    user op2 insecure-password hoochi-mama2

frontend app.example.com
    log-format %ci:%cp\ [%t]\ %ft/%b/%s\ %Tq/%Tw/%Tc/%Tr/%Tt\ %ST\ %U/%B\ %tsc\ %ac/%fc/%bc/%sc/%rc\ %sq/%bq\ %hr\ %hs\ %{+Q}r

    # enable https (haproxy v1.5-dev required)
    # highly recommended to use *.example.com certificate to avoid browser warnings on illegal hostnames
    bind                       :443 ssl crt /path/to/bundle/star.example.com.pem ciphers RC4:HIGH:!aNULL:!MD5
    # modify request headers
    reqadd                     X-Forwarded-Proto:\ https
    reqadd                     X-Forwarded-Port:\ 443
    # modify response headers
    rspdel                     ^Server:.*
    rspdel                     ^X-Powered-By:.*
    rspadd                     Server:\ Dethklok\ (Unix/0.2.3)
    rate-limit sessions        1024

    # haproxy health status
    monitor-uri                /my-health
    monitor-net                10.27.5.64/26

    # guess environment
    acl host-demo              hdr_beg(host) -i demo.
    acl host-devel             hdr_beg(host) -i devel.
    acl host-live              hdr_beg(host) -i www.

    acl is-static-file         path_beg -i /css /js /img /fonts /assets
    acl is-static-file         path_end -i .jpg .png .gif .jpeg .js .css .html .ico .woff .eot .ttf .svg
    acl is-haproxy-stats       path_beg /stats

    use_backend haproxy        if is-haproxy-stats

    use_backend static-demo    if host-demo is-static-file
    use_backend dynamic-demo   if host-demo !is-static-file

    use_backend static-devel   if host-devel is-static-file
    use_backend dynamic-devel  if host-devel !is-static-file

    use_backend static-live    if host-live is-static-file
    default_backend            dynamic-live

#
# HAProxy statistics
#
backend haproxy
    acl is-authnd       http_auth(dev-ops)
    stats uri           /stats
    stats refresh       180s
    stats http-request  auth realm app.example.com\ haproxy\ statistics unless is-authnd
    stats hide-version
    stats show-legends

#
# backends for demo.example.com (demo/lite production environment)
#    
backend static-demo
    option httpchk HEAD /favicon.ico HTTP/1.1\r\nHost:\ demo.example.com
    server ngx1 app-be1.example.net:4040 check inter 30s fall 2 rise 3
    server ngx2 app-be2.example.net:4040 check inter 30s fall 2 rise 3

backend dynamic-demo
    option httpchk HEAD / HTTP/1.1\r\nHost:\ demo.example.com
    server sta1 app-be1.example.net:3040 check inter 30s fall 2 rise 3
    server sta2 app-be2.example.net:3040 check inter 30s fall 2 rise 3

#
# backends for devel.example.com (development environment)
#
backend static-devel
    option httpchk HEAD /favicon.ico HTTP/1.1\r\nHost:\ devel.example.com
    server ngx1 app-be1.example.net:4020 check inter 30s fall 2 rise 3
    server ngx2 app-be2.example.net:4020 check inter 30s fall 2 rise 3

backend dynamic-devel
    option httpchk HEAD / HTTP/1.1\r\nHost:\ devel.example.com
    server sta1 app-be1.example.net:3020 check inter 30s fall 2 rise 3
    server sta2 app-be2.example.net:3020 check inter 30s fall 2 rise 3
 
#
# backends for www.example.com (production environment)
#
backend static-live
    option httpchk HEAD /favicon.ico HTTP/1.1\r\nHost:\ www.example.com
    server ngx1 app-be1.example.net:4000 check inter 30s fall 2 rise 3
    server ngx2 app-be2.example.net:4000 check inter 30s fall 2 rise 3

backend dynamic-live
    option httpchk HEAD / HTTP/1.1\r\nHost:\ www.example.com
    server sta1 app-be1.example.net:3000 check inter 30s fall 2 rise 3
    server sta2 app-be2.example.net:3000 check inter 30s fall 2 rise 3