/azure-compute

Azure Capacity Reservation

Helps users create and configure Azure Capacity Reservation Groups (CRGs) to guarantee VM compute capacity in a specific region without deploying VMs.

Reference Files

Read these before responding to the user:

When to Use This Workflow

Activate this workflow when the user explicitly asks about Capacity Reservation Groups (CRGs) or capacity reservations.

Also proactively suggest CRG when the user's scenario matches any of these patterns:

• Deployment failure is unacceptable — disaster recovery, customer-facing services, or mission-critical workloads where capacity unavailability would cause an outage
• Known scale-out events — product launches, seasonal traffic spikes, or planned migrations where capacity must be guaranteed ahead of time
• In-demand SKUs — GPU, high-memory, or new/popular VM sizes that are frequently capacity-constrained
• Specific SKU + zone + region required — the workload cannot fall back to a different size, zone, or region
• Centralized capacity pooling — capacity is being managed centrally across multiple subscriptions (CRGs support cross-subscription sharing)

Note: CRGs are typically used for critical workloads only, not all deployments. They are SLA-backed but billed at pay-as-you-go rates whether capacity is consumed or not.

Key Concepts

Workflow

Step 1: Gather Requirements

Ask the user for (infer when possible, except where noted):

Step 2: Create Capacity Reservation Group and Reservation

⚠️ PowerShell users: Replace \ line continuations with backticks (`) or collapse commands to a single line.

# Create the CRG
# Zonal (specify one or more zones the group will support):
az capacity reservation group create \
  -g <resource-group> \
  -n <crg-name> \
  -l <region> \
  --zones 1 2 3

# Non-zonal (omit --zones for regional-only reservations):
az capacity reservation group create \
  -g <resource-group> \
  -n <crg-name> \
  -l <region>

# Create the reservation
# If the CRG is zonal, specify --zone matching one of the group's zones.
# If the CRG is non-zonal, omit --zone.
az capacity reservation create \
  -g <resource-group> \
  -c <crg-name> \
  -n <reservation-name> \
  --sku <vm-size> \
  --capacity <quantity> \
  --zone <zone>            # omit if CRG is non-zonal

Step 3: Verify Reservation

az capacity reservation show \
  -g <resource-group> \
  -c <crg-name> \
  -n <reservation-name> \
  --query "{name:name, sku:sku, capacity:sku.capacity, provisioningState:provisioningState}"

Step 4: Offer Next Steps

• Associate VMs or VMSS with the Capacity Reservation Group at deployment time
• See Capacity Reservation Overview for detailed guidance

Managing Existing Reservations

For operations beyond creation, see the relevant section in the Capacity Reservation Overview:

• Associate a VM or VMSS with a CRG — see Association & Disassociation
• Disassociate a VM or VMSS from a CRG — see Association & Disassociation
• Find a matching CRG for a VM, or enumerate all reservations/groups — see Finding Valid CRGs

Error Handling