Attempts to reserve capacity across Azure zones for a selected VM SKU.

azure-vm-capacity-reservation-check-and-reserve.sh

#!/bin/bash

# -----------------------------------------------------------------------------
# DISCLAIMER:
# This script is provided as a sample for informational purposes only.
# There is no guarantee of fitness for a particular purpose, and it may not be
# suitable for use in production environments. Use at your own risk.
# The authors and distributors accept no liability for any damages or losses
# resulting from the use or misuse of this script. Review, test, and modify
# as needed before deploying in any environment.
# -----------------------------------------------------------------------------

set -e

# --- User-defined variables ---
SUBSCRIPTION_ID="yourSubscriptionId"
RG_NAME="yourResourceGroup"
LOCATION="eastus2"
CRG_NAME="yourCapacityReservationGroup"
VM_SIZE="Standard_E32s_v5"
TARGET_COUNT=15
ZONES="1 2 3"

# --- Check if user is logged in to Azure CLI ---
echo "Checking if user is logged in to Azure CLI..."
if ! az account show >/dev/null 2>&1; then
  echo "Not logged in to Azure CLI. Attempting to log in..."
  az login
fi

USER=$(az account show --query user.name -o tsv 2>/dev/null)
if [ -n "$USER" ]; then
  echo "Logged in as: $USER"
fi

# --- Set the subscription ---
az account set --subscription "$SUBSCRIPTION_ID"

# --- Check if Capacity Reservation Group exists ---
echo "Checking if Capacity Reservation Group '$CRG_NAME' exists..."

CRG_EXISTS=$(az capacity reservation group show \
  --resource-group "$RG_NAME" \
  -n "$CRG_NAME" \
  --query "name" \
  --output tsv 2>/dev/null || true)

if [ -z "$CRG_EXISTS" ]; then
  echo "Capacity Reservation Group not found. Creating group..."
  az capacity reservation group create \
    --resource-group "$RG_NAME" \
    --location "$LOCATION" \
    -n "$CRG_NAME" \
    --zones $ZONES
else
  echo "Capacity Reservation Group '$CRG_NAME' already exists."
fi

# --- Get current reservations for the specified SKU in each zone ---
for ZONE in $ZONES; do
  echo "Retrieving current reserved quantity for VM size '$VM_SIZE' in zone '$ZONE'..."

  CURRENT_COUNT=$(az capacity reservation list \
    --resource-group "$RG_NAME" \
    --capacity-reservation-group "$CRG_NAME" \
    --query "[?sku.name=='$VM_SIZE' && properties.zone=='$ZONE'].properties.quantity" \
    --output tsv | awk '{sum+=$1} END {print sum}')

  if [ -z "$CURRENT_COUNT" ]; then
    CURRENT_COUNT=0
  fi

  # --- Calculate how many more are needed ---
  NEEDED_COUNT=$((TARGET_COUNT - CURRENT_COUNT))

  # --- Output summary ---
  echo "Zone: $ZONE"
  echo "Current reserved count: $CURRENT_COUNT"
  echo "Target reserved count: $TARGET_COUNT"

  if [ "$NEEDED_COUNT" -le 0 ]; then
    echo "Reservation target already met or exceeded for zone '$ZONE'. No further action needed."
  else
    echo "Additional $NEEDED_COUNT instance(s) needed to meet target for zone '$ZONE'."

    for ((i = 1; i <= NEEDED_COUNT; i++)); do
      RES_NAME="${CRG_NAME}-${VM_SIZE//_/}-zone${ZONE}-resv-$((CURRENT_COUNT + i))"
      echo "Creating capacity reservation '$RES_NAME' for VM size '$VM_SIZE' in zone '$ZONE'..."
      az capacity reservation create \
        --resource-group "$RG_NAME" \
        --capacity-reservation-group "$CRG_NAME" \
        -n "$RES_NAME" \
        --sku "$VM_SIZE" \
        --capacity 1 \
        --location "$LOCATION" \
        --zone "$ZONE"
    done

    echo "All required reservations have been created for zone '$ZONE'."
  fi

done