Reload behaviour with AWS EC2 service discovery

Help!
1

Hello. I was wondering if someone can help me as I’m a bit stuck. I am testing out the AWS EC2 Service discovery feature with the Data Plane API. I’ll put my configurations for both the /etc/haproxy/dataplaneapi.yml file and the Service Discovery configuration below.

dataplaneapi.yml

config_version: 2
name: i-04568442dd67098c5
dataplaneapi:
  host: 0.0.0.0
  port: 5555
  advertised:
    api_address: ""
    api_port: 0
  scheme:
  - http
  userlist:
    userlist: dataplaneapi
  transaction:
    transaction_dir: /var/lib/dataplaneapi/transactions
    backups_number: 10
    backups_dir: /var/lib/dataplaneapi/backups
  resources:
    maps_dir: /etc/haproxy/maps
    ssl_certs_dir: /etc/haproxy/ssl
    general_storage_dir: /etc/haproxy/general
    spoe_dir: /etc/haproxy/spoe
haproxy:
  config_file: /etc/haproxy/haproxy.cfg
  haproxy_bin: /usr/sbin/haproxy
  reload:
    reload_delay: 5
    service_name: haproxy
    reload_strategy: systemd
log_targets:
- log_to: file
  log_file: /var/log/dataplaneapi.log
  log_level: info
  log_types:
  - access
  - app

Service Discovery configuration

[
  {
    "description": "Production Environment",
    "enabled": true,
    "id": "e551c0e9-3796-4dd3-b33d-962c7c74e508",
    "ipv4_address": "private",
    "name": "ttek-prod",
    "region": "eu-west-1",
    "retry_timeout": 10,
    "server_slots_base": 10,
    "server_slots_growth_increment": 5,
    "server_slots_growth_type": "exponential"
  }
]

From my understanding, having unused slots should mean reloads won’t happen as often but what I am finding is that any time I add a new server to my ASG, HAProxy is reloading automatically once it sees the new server. I have a total of 10 slots available per backend (as 10 is set for server_slots_base ) and I’m only trying to add a 2nd server which I wasn’t expecting would result in a reload given my configuration. When I add a new server to my ASG, HAProxy reloads and it adds the server IP under the backend in the haproxy.cfg file as well.

Not sure if I have something mis-configured, or maybe I’ve just misunderstood how this worked. I read in HAProxy documentation that the runtime API was meant to minimize reloads during AWS EC2 Auto scaling events. Thank you.