haproxy.cfg

# configuration for haproxy, a load balancer
# lives in: /etc/haproxy/haproxy.cfg

# very basic config that load balances port 80 to 8080 on the backend servers
global
  daemon
  maxconn 15000 # Max simultaneous connections from an upstream server
  spread-checks 5 # Distribute health checks with some randomness

defaults
  mode http
  option abortonclose # abort request if client closes output channel while waiting
  #option httpclose # add "Connection:close" header if it is missing
  option http-server-close # (better according to https://tech.shareaholic.com/2012/10/26/haproxy-a-substitute-for-amazon-elb/)
  option forwardfor # insert x-forwarded-for header so that app servers can see both proxy and client IPs
  option redispatch # any server can handle any session - redistribute connections if a backend server goes down
  timeout client 60s
  timeout connect 9s
  timeout server 30s
  timeout check 5s
  stats enable
  stats uri /haproxy-stats #web frontend available at *:80/haproxy-stats
  stats realm Haproxy\ Statistics
  stats auth user:password
  monitor-uri /haproxy-monitor # Returns 200 if we're up; real path redacted
  errorfile	400	/etc/haproxy/errors/400.http
  errorfile	403	/etc/haproxy/errors/403.http
  errorfile	408	/etc/haproxy/errors/408.http
  errorfile	500	/etc/haproxy/errors/500.http
  errorfile	502	/etc/haproxy/errors/502.http
  errorfile	503	/etc/haproxy/errors/503.http
  errorfile	504	/etc/haproxy/errors/504.http

frontend http-in
  bind *:80
  reqadd X-Forwarded-Proto:\ http
  default_backend servers

frontend ssl-http-in
  bind *:443 ssl crt /etc/ssl/somekey.pemkey
  reqadd X-Forwarded-Proto:\ https
  default_backend servers

backend servers
  redirect scheme https if !{ ssl_fc }
  balance leastconn
  cookie SERVERID insert indirect nocache maxidle 1h
  option httpchk HEAD /index.html HTTP/1.0\r\nUser-Agent:\ HAProxy01
  rspadd Access-Control-Allow-Origin:\ *
  #
  # Add a header for IE to bypass any compatibility mode settings.
  rspadd X-UA-Compatible:IE=edge,chrome=1
  # enumerate our running web instances, they should look like the line below:
  # server webA 172.31.11.211:8080 cookie A check maxconn 5000
  # Note: these are populated automatically from a template any time
  #       a new web server is brought online or taken out of the pool
  server i-637caa68 11.0.0.1:8080 cookie i-637caa68 check maxconn 5000
  server i-e17aacea 11.0.0.2:8080 cookie i-e17aacea check maxconn 5000