Add config snippet and 429.http file.

The haproxy.cfg file contains just a snippet
to be modified and included in your own
HAProxy configuration.

The 429.http file can be used verbatim.

429.http

@@ -0,0 +1,7 @@
+HTTP/1.1 429 Too Many Requests
+Cache-Control: no-cache
+Connection: close
+Content-Type: text/plain
+Retry-After: 60
+
+Too Many Requests (HAP429).

haproxy.cfg

@@ -0,0 +1,24 @@
+frontend fe_api_ssl
+  bind 192.168.0.1:443 ssl crt /etc/haproxy/ssl/api.pem no-sslv3 ciphers ...
+  default_backend be_api
+
+  tcp-request inspect-delay 5s
+
+  acl document_request path_beg -i /v2/documents
+  acl is_upload hdr_beg(Content-Type) -i multipart/form-data
+  acl too_many_uploads_by_user sc0_gpc0_rate() gt 100
+  acl mark_seen sc0_inc_gpc0 gt 0
+
+  stick-table type string size 100k store gpc0_rate(60s)
+
+  tcp-request content track-sc0 hdr(Authorization) if METH_POST document_request is_upload
+
+  use_backend 429_slow_down if too_many_uploads_by_user mark_seen 
+
+backend be_429_slow_down
+  timeout tarpit 2s
+  errorfile 500 /etc/haproxy/errorfiles/429.http
+  http-request tarpit
+
+backend be_api
+  ...