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Examples

Custom HTTP headers in health check

This example adds the Host header to the health check executed by HAProxy:

{
  "id":"app",
  "labels":{
    "HAPROXY_GROUP":"external",
    "HAPROXY_0_BACKEND_HTTP_OPTIONS":"option  httpchk GET {healthCheckPath} HTTP/1.1\\r\\nHost: www\n  timeout check {healthCheckTimeoutSeconds}s"
  }
}

Setting timeout for long-lived socket connections

If you're trying to run a TCP service which uses long-lived sockets through HAProxy, such as a MySQL instance, you'll need to set longer timeouts for the backend. Try the following:

{
  "id":"app",
  "labels":{
    "HAPROXY_GROUP":"external",
    "HAPROXY_0_BACKEND_HEAD":"backend {backend}\n  balance {balance}\n  mode {mode}\n  timeout server 30m\n  timeout client 30m\n"
  }
}

The example above will set the client and server timeout to 30 minutes for the specified backend.

SSL Termination at an Elastic Load Balancer

Sometimes you want to allow an ELB to terminate SSL for you, but you still want marathon-lb to redirect non-HTTPS requests. ELBs use HTTP headers to communicate that the request came in via a secure channel and has been decrypted. Specifically, if the X-Forwarded-Proto header is set to https, then the request was decrypted by the ELB.

Unless you tell HAProxy to look for the X-Forwarded-Proto header, the request will appear as if it's unencrypted and will get redirected using standard the rules.

"labels": {
  "HAPROXY_BACKEND_HTTP_OPTIONS": "  acl is_proxy_https hdr(X-Forwarded-Proto) https\n  redirect scheme https unless { ssl_fc } or is_proxy_https\n"
}

This configuration instructs marathon-lb to generate a backend rule that looks for the X-Forwarded-Proto header or a regular TLS connection and redirect if neither are specified.