Azure Load Balancer: Basic Configuration

Step 1: Create an Azure Load Balancer

Navigate to the Azure portal and search for "Load balancers". Click "Create load balancer".

• Subscription and Resource group: Select appropriate values.
• Name: Provide a unique name for your load balancer.
• Region: Choose the region where your resources are located.
• SKU: For basic configurations, choose 'Standard' for more features and availability, or 'Basic' for simpler scenarios. For this guide, we'll assume 'Standard'.
• Type: Select 'Public' for internet-facing applications or 'Internal' for applications accessible only within your VNet.
• Public IP address: Create a new public IP address or select an existing one for the frontend.

Click "Review + create" and then "Create".

Step 2: Configure the Backend Pool

Once the load balancer is deployed, go to its resource page and navigate to "Backend pools". Click "Add".

• Name: Provide a name for your backend pool.
• Virtual machines: Select the VMs or VMSS you want to include in this pool.
• Network interface: Ensure the correct network interface is selected for each VM.

Click "Add" to save the backend pool.

Step 3: Create a Health Probe

In the load balancer resource, navigate to "Health probes" and click "Add".

• Name: A descriptive name for the probe (e.g., http-probe).
• Protocol: Select the protocol your application uses (e.g., HTTP, TCP, HTTPS).
• Port: The port on your backend VMs that the probe will check (e.g., 80 for HTTP).
• Path (if HTTP/HTTPS): The URL path for the probe to check (e.g., /health).
• Interval: The time in seconds between probe attempts.
• Unhealthy threshold: The number of consecutive probe failures before an instance is marked as unhealthy.

Click "Add".

Step 4: Configure a Load Balancing Rule

Navigate to "Load balancing rules" and click "Add".

• Name: A descriptive name (e.g., web-traffic-rule).
• IP Version: IPv4 or IPv6.
• Frontend IP address: Select the frontend IP you configured.
• Protocol: TCP or UDP.
• Port: The port clients will connect to (e.g., 80 for HTTP).
• Backend port: The port your application is listening on the backend VMs (often the same as the frontend port, e.g., 80).
• Backend pool: Select the backend pool you created.
• Health probe: Select the health probe you created.
• Session persistence: Choose whether to direct a client to the same backend instance for the duration of a session (None, Client IP, Client IP and protocol).
• Floating IP (Direct Server Return): Enable if your scenario requires it (usually for specific high-availability scenarios like SQL Server Always On).

Click "Add".

# Create a Load Balancer
az network lb create \
    --name myLoadBalancer \
    --resource-group myResourceGroup \
    --frontend-ip-name myFrontendIP \
    --public-ip-address myPublicIP \
    --sku Standard

# Create a Backend Pool
az network lb address-pool create \
    --lb-name myLoadBalancer \
    --resource-group myResourceGroup \
    --name myBackendPool

# Add a VM to the Backend Pool (example)
az network nic ip-config address-pool add \
    --ip-config-name ipconfig1 \
    --lb-name myLoadBalancer \
    --resource-group myResourceGroup \
    --pool-name myBackendPool \
    --nic-name myVMnic

# Create a Health Probe
az network lb probe create \
    --lb-name myLoadBalancer \
    --resource-group myResourceGroup \
    --name myHTTPProbe \
    --protocol http \
    --port 80 \
    --path /health

# Create a Load Balancing Rule
az network lb rule create \
    --lb-name myLoadBalancer \
    --resource-group myResourceGroup \
    --name myHTTPRule \
    --protocol tcp \
    --frontend-port 80 \
    --backend-port 80 \
    --frontend-ip-name myFrontendIP \
    --backend-pool-name myBackendPool \
    --probe-name myHTTPProbe

Further Reading

• Azure Load Balancer documentation overview
• Load balancing rules
• Health probes