Load Balancing

Load balancing refers to distributing incoming traffic across a group of backend server. In order to serve a high volume of concurrent requests from users or clients, it is required to have a “traffic distributer” sitting in front of the backend servers, and routing requests across all workers capable of fulfilling those requests.

The load balancer is responsible for the following functions:

• Distributes client requests or network load efficiently across multiple backend servers

• Ensures high availability and reliability by sending requests only to servers that are online and that can handle the request in a timely manner

• Provides the flexibility to scale-up or scale-down as demand dictates

In the context of the Object Storage, a Proxy Virtual Controller is referred to as a backend server.

How load is balanced in the Object Storage

The NextGen Object Storage load-balancer has two modes of operation:

Internal load balancer (default)

Any NextGen Object Storage is provisioned with a built-in Load Balancer (referred to as Internal Load Balancer) solution which will work seamlessly out of the box. The internal load balancer is fully configured to provide a secured, reliable and highly-available endpoint. Upon provisioning a new Object Storage instance, the system will be have a globally unique FQDN matching the Object Storage front-end network, along with a matching well-known CA certificate that will be used for a secured communication over HTTPS.

In case a public IP/additional VNI (Virtual Network Interface) is allocated to the Object Storage, the internal load balancer will be used to distribute the workload. The main difference between Frontend network and Public/VNI handling is the load balancer mode of operation:

• Frontend - DSR (Direct Server Return), packets from the Object Storage Virtual Controller bypass the Load Balancer, maximizing egress throughput.

• Public/VNI - The load balancer will be used as a gateway for all traffic from/to the Object Storage Virtual Controller.

Load balancing algorithm

The load balancer is configured to use weighted least connection (wlc) - new connections go to the worker with the least number of connections. Reminder - Controller VCs and Storage VCs are excluded from handling client/users operations.

High availability

As with all other core services in the system, the internal load balancer is highly available. The internal load balancer service will be hosted in a Controller VC (vc-1) and in case of a failure will failover to vc-0 to ensure service continuity.

Load balancer metering

While the actual Object Storage operations will be distributed to the “backend servers”, in some cases the system administrator would like to review the amount of concurrent sessions their Object Storage is handling.

In the NextGen Object Storage the active session count can be reviewed in the management interface:

1. Virtual Controllers view - navigate to the Virtual Controller view and select the virtual controller with vc-1 as ID. In the south pane, select the Frontend Metering tab.

2. Performance section - under the system section, navigate to the Performance section. Expand the Virtual Controller > Controller > vc-1 view and drag and drop the Active Connections pane.

The Active Connections connections graph will provide a breakdown of connections within the Object Storage (per VC). The user can toggle between the graph view and a the table view using the TABLES view.

Using an external load balancer

Zadara’s Object Storage provides an easy way to integrate with an existing or newly provisioned software/hardware load balancer.

The main purpose is to expose the Object Storage S3 interface to external applications.

There are many load balancer solutions in the market. The procedures for setting them up are quite similar. This appendix gives an example of HAproxy, an open-source TCP/HTTP load-balancing proxy server available at www.haproxy.org

The following example sets up an external load balancer to terminate TLS connections and distribute them across all Proxy VCs.

This configuration provides secure and efficient traffic management for all NextGen Object Storage services.:

• SSL Termination occurs on the external load balancer for both Object Operation APIs and GUI connections. This setup ensures centralized TLS handling.

  However, authentication traffic is always terminated within the Object Storage system itself.

• A custom TLS certificate installed on the load balancer is used to secure all TLS connections.

• Object Operation connections are forwarded to the NextGen Object Storage proxy virtual controllers (VCs), with uneven traffic distribution. Proxy VCs handle the majority of the load, storage VCs carry less load, and HA VCs carry the least load.

• The load balancer preserves client visibility by adding a header with the original client IP address, enabling accurate logging and traceability within the Object Storage proxies.

• Continuous HTTP-based health checks are performed by the load balancer to monitor the availability of all proxy VCs.

• Authentication connections are forwarded to the Object Storage floating IP using SSL pass-through, where TLS is terminated by the Object Storage system itself. A matching custom TLS certificate must also be uploaded there.

• User Interface (GUI) traffic is redirected to the Object Storage floating IP over port 8443, providing secure access to the management interface.

• A graphical statistics interface is enabled on the load balancer to monitor connection status, backend health, and traffic metrics.

Object Storage Settings

1. Set the internet-facing domain-name/IP of the external LoadBalancer as the NextGen Object Storage API Hostname/IP.

2. Upload your custom TLS certificate. It will be used for authentication connections. The certificate should match the custom domain name.

3. Set SSL Termination to “External”.

HAProxy Configuration

This example configuration was tested on HAProxy version 2.8.5-1ubuntu3.4 2025/10/01.

This configuration sets up HAProxy as a secure, multi-service reverse proxy and load balancer for Zadara’s Object Storageoperations, authentication, and GUI components.

It terminates TLS on the frontends, forwards requests to internal application nodes, performs health checks, and exposes HAProxy’s small management interface for monitoring.

A custom TLS certificate is required when TLS termination occurs in the HAProxy server. HTTP requests are sent to the Object Storage Proxy controllers.

In this configuration, the following addresses and roles are used:

Frontends definitions

Backends definitions

Stats/Admin Interface

• Listen section: bind *:1936 (should be restricted internally)

• Provides a small HTTP page for live stats and backend health.

• Currently protected by basic auth (zadara:zadara) — should be restricted or replaced with stronger credentials.

Misc Options

• SSL termination: TLS handled at the frontend (cert: /etc/ssl/private/zadara_custom.pem)

• Forwarded headers: Preserves client IP (X-Forwarded-For) and scheme (X-Forwarded-Proto) for accurate logging and app behavior.

• Health checks: Each backend periodically checks /healthcheck for status 200; failed servers are marked DOWN automatically.

• Limits & tuning: maxconn 2048, sensible timeouts (5s connect, 50s client/server).

• Security baseline: TLS1.2+ only.

Known Limitation

Currently, the GUI will not allow mixed HTTPS and HTTP content. Therefore, if the management interface is required for console operation, it must be exposed internally or used via an S3-compatible Object Storage browser/CLI tool.

HAProxy configuration file

Configure /etc/haproxy/haproxy.cfg.

Example:

global
   maxconn 2048
   log /dev/log local0
   log /dev/log local1 notice
   chroot /var/lib/haproxy
   stats socket /run/haproxy/admin.sock mode 660 level admin
   stats timeout 30s
   user haproxy
   group haproxy
   daemon
   tune.ssl.default-dh-param 2048

   # Default SSL material locations
   ca-base /etc/ssl/certs
   crt-base /etc/ssl/private

   # SSL defaults (adjust to your policy)
   ssl-default-bind-options no-sslv3 no-tlsv10 no-tlsv11
   ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
   ssl-default-bind-ciphersuites TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256

defaults
   log     global
   mode    http
   option  httplog
   option  dontlognull
   timeout connect 5s
   timeout client  50s
   timeout server  50s
   option http-server-close
   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 fe-object-operations
   bind 10.0.1.55:443 ssl crt /etc/ssl/private/zadara_custom.pem
   mode http
   option forwardfor if-none
   http-request set-header X-Forwarded-Proto https
   default_backend be-ngos-object-operations

frontend fe-auth
   bind 10.0.1.55:5000
   mode tcp
   option tcplog
   default_backend be-floating-ngos-auth

frontend fe-gui
   bind 10.0.1.55:8443 ssl crt /etc/ssl/private/zadara_custom.pem
   mode http
   option forwardfor if-none

   # Tell the app the original client details
   http-request set-header X-Forwarded-For   %[src]
   http-request set-header X-Forwarded-Proto https
   http-request set-header X-Forwarded-Host  %[req.hdr(Host)]
   http-request set-header X-Forwarded-Port  %[dst_port]
   # Some Rails setups also look at this:
   http-request set-header X-Forwarded-Ssl   on

   default_backend be-floating-ngos-gui

backend be-floating-ngos-gui
   mode http
   option httpchk
   http-check send meth HEAD uri / ver HTTP/1.0
   http-check expect status 200
   server ngos-floating 172.16.224.114:8080 check

backend be-ngos-object-operations
   mode http
   balance roundrobin
   option forwardfor if-none
   option httpchk
   http-check send meth HEAD uri /healthcheck ver HTTP/1.0
   http-check expect status 200
   server ngos-proxy-01 172.16.224.110:80 weight 100 check
   server ngos-proxy-02 172.16.224.111:80 weight 100 check

backend be-floating-ngos-auth
   mode tcp
   option tcp-check
   server ngos-floating 172.16.224.114:5000 check

listen stats
   bind *:1936
   mode http
   stats enable
   stats uri /
   # For stronger auth, replace with a userlist and 'stats auth user:pass' with a hashed password
   stats auth zadara:zadara