Load Balancer Introduction

Overview

Octavia is a scalable, operator-managed Layer 4-7 Load Balancer as a Service (LBaaS) for UNIQCloud. It provides key features to distribute incoming traffic across multiple backend instances:

• High Availability (HA): Active/standby or active/active configurations.
• Session Persistence: Ensures client requests are routed to the same backend server.
• Multiple Load Balancing Algorithms: Round Robin, Least Connections, Source IP, etc.
• Listener Types: Supports TCP, HTTP, HTTPS, and TERMINATED_HTTPS.
• Health Monitoring: Continuous probes to check backend server health.

CLIENT IP PASS-THROUGH (PROXY PROTOCOL)

To ensure the client IP address is passed through to the backend servers, you must configure the PROXY protocol (v2) on the listener. This is critical for applications that rely on the client's IP for logging, security, or session persistence.

Note that the backend servers must also be configured to parse the PROXY protocol header to extract the client IP.

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Configuration Options

1. Session Persistence

Session persistence ensures that requests from the same client are always routed to the same backend server. The following types are supported:

• SOURCE_IP: Persistence based on the client's source IP address.
• HTTP_COOKIE: Persistence using HTTP cookies.
• APP_COOKIE: Persistence using application cookies.

Example: Enable Session Persistence for a Pool

openstack loadbalancer pool create \
  --name my-pool \
  --lb-algorithm ROUND_ROBIN \
  --listener <listener-id> \
  --protocol HTTP \
  --session-persistence type=SOURCE_IP

2. High Availability (HA)

The Load Balancer supports active/standby and active/active HA configurations. HA is enabled by default for most deployments.

Example: Create an HA Load Balancer

openstack loadbalancer create \
  --name my-ha-lb \
  --vip-subnet-id <subnet-id> \
  --provider octavia \
  --availability-zone nova

3. Load Balancing Algorithms

The following algorithms are supported for distributing traffic among backend servers:

Algorithm	Description
ROUND_ROBIN	Distributes requests sequentially across the backend servers.
LEAST_CONNECTIONS	Sends requests to the backend server with the fewest active connections.
SOURCE_IP	Uses a hash of the client's source IP to determine the backend server.
URI	Uses a hash of the request URI to determine the backend server.
HTTP_HEADER	Uses a hash of a specified HTTP header to determine the backend server.

Example: Set Algorithm for a Pool

openstack loadbalancer pool create \
  --name my-pool \
  --lb-algorithm LEAST_CONNECTIONS \
  --listener <listener-id> \
  --protocol HTTP

4. Listener Types

A listener defines the port and protocol for incoming traffic to the load balancer. The following listener types are supported:

Listener Type	Protocol	Port	Use Case
TCP	TCP	Any	Generic TCP load balancing (databases, custom applications).
HTTP	HTTP	80	Web traffic without encryption.
HTTPS	HTTPS	443	Encrypted web traffic (end-to-end encryption).
TERMINATED_HTTPS	HTTPS	443	Encrypted web traffic where the load balancer terminates SSL/TLS.
UDP	UDP	Any	UDP-based applications (DNS, VoIP).

Example: Create a Listener

# Create an HTTP listener
openstack loadbalancer listener create \
  --name my-http-listener \
  --protocol HTTP \
  --protocol-port 80 \
  --loadbalancer <lb-id>

# Create a TERMINATED_HTTPS listener (SSL termination)
openstack loadbalancer listener create \
  --name my-https-listener \
  --protocol TERMINATED_HTTPS \
  --protocol-port 443 \
  --loadbalancer <lb-id> \
  --default-tls-container-ref <tls-container-id>

5. PROXY Protocol (v2) Configuration

To ensure the client IP address is passed through to backend servers, configure the PROXY protocol (v2) on the listener:

openstack loadbalancer listener set \
  --proxy-protocol \
  <listener-id>

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Complete Management Lifecycle

Create a Load Balancer with HTTP Listener and Pool

# Step 1: Create a load balancer
openstack loadbalancer create \
  --name my-lb \
  --vip-subnet-id <subnet-id> \
  --provider octavia

# Step 2: Create an HTTP listener with PROXYv2 enabled
openstack loadbalancer listener create \
  --name my-http-listener \
  --protocol HTTP \
  --protocol-port 80 \
  --loadbalancer <lb-id>

openstack loadbalancer listener set \
  --proxy-protocol \
  <listener-id>

# Step 3: Create a pool with ROUND_ROBIN algorithm
openstack loadbalancer pool create \
  --name my-pool \
  --lb-algorithm ROUND_ROBIN \
  --listener <listener-id> \
  --protocol HTTP

# Step 4: Add backend servers (members) to the pool
openstack loadbalancer member create \
  --name member1 \
  --address <server-ip-1> \
  --protocol-port 80 \
  --subnet-id <subnet-id> \
  --pool <pool-id>

openstack loadbalancer member create \
  --name member2 \
  --address <server-ip-2> \
  --protocol-port 80 \
  --subnet-id <subnet-id> \
  --pool <pool-id>

# Step 5: Enable session persistence for the pool
openstack loadbalancer pool set \
  --session-persistence type=SOURCE_IP \
  <pool-id>

Delete a Load Balancer and Its Resources

# Step 1: Delete members from the pool
openstack loadbalancer member delete <member-id-1>
openstack loadbalancer member delete <member-id-2>

# Step 2: Delete the pool
openstack loadbalancer pool delete <pool-id>

# Step 3: Delete the listener
openstack loadbalancer listener delete <listener-id>

# Step 4: Delete the load balancer
openstack loadbalancer delete <lb-id>

# Alternative: Force delete a load balancer and all cascading resources
openstack loadbalancer delete --cascade <lb-id>

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CLI Querying & Troubleshooting

Use the following table to debug common issues with Load Balancer instances:

Issue	Possible Cause	Solution
Load balancer stuck in PENDING_CREATE	Insufficient resources or network issues	Check logs and ensure sufficient quotas.
Listener fails to create	Invalid protocol or port	Verify the protocol and port are supported.
Backend servers not receiving traffic	Incorrect member configuration	Check member IPs, ports, and security groups.
Session persistence not working	Misconfigured persistence type	Verify the persistence type and backend support.
Client IP not visible to backend	PROXY protocol not enabled	Enable PROXYv2 on the listener and configure backend to parse it.

# List all load balancers
openstack loadbalancer list

# Show details of a specific load balancer
openstack loadbalancer show <lb-id>