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Overview

The Hypervisor class provides an interface for working with OpenStack compute hosts (hypervisors). Hypervisors are the physical or virtual machines that run your cloud instances. This guide shows you how to query hypervisor information and monitor the servers running on them.

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Creating a Hypervisor Instance

1

Initialize by hostname

Create a hypervisor instance using the hostname:
from myos.hypervisor import Hypervisor

hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk")
2

Initialize by ID

Alternatively, create a hypervisor instance using the hypervisor ID:
hypervisor = Hypervisor(hypervisor_id="42")
3

Specify cloud configuration

Optionally specify a custom cloud configuration:
from myos.cloud import Cloud

cloud = Cloud(cloud="admin")
hypervisor = Hypervisor(name="hv300.nubes.rl.ac.uk", cloud=cloud)
Hypervisor operations typically require administrator privileges in OpenStack.

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Querying Hypervisor Properties

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Basic Properties

Access core hypervisor information: 
from myos.hypervisor import Hypervisor

hypervisor = Hypervisor(name="hv300.nubes.rl.ac.uk")

# Get hypervisor details
print(hypervisor.hostname)  # Hypervisor hostname
print(hypervisor.name)      # Same as hostname
print(hypervisor.id)        # Hypervisor ID
The name and hostname properties are equivalent for the Hypervisor class.

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Status and State

Check the operational status of a hypervisor: 
hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk")

print(f"Status: {hypervisor.status}")
print(f"State: {hypervisor.state}")
Status indicates whether the hypervisor is enabled:
  • enabled: Hypervisor is active and can host VMs
  • disabled: Hypervisor is disabled
State indicates the hypervisor’s current operational state:
  • up: Hypervisor is running normally
  • down: Hypervisor is not responding
Always check both status and state to get a complete picture of hypervisor health.

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Managing Servers on Hypervisors

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Listing All Servers

Retrieve all servers running on a specific hypervisor: 
from myos.hypervisor import Hypervisor

hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk")

# Get all servers on this hypervisor
servers = hypervisor.servers

print(f"Hypervisor {hypervisor.hostname} hosts {len(servers)} servers\n")

for server in servers:
    print(f"Server: {server.name}")
    print(f"  ID: {server.id}")
    print(f"  Status: {server.status}")
    print(f"  Flavor: {server.flavor.name}")
    print()

Hypervisor hv-a100x8-8.nubes.rl.ac.uk hosts 3 servers

Server: vwn-gpu-2025-12-05-21-03-17-0
  ID: 79b3b46d-c7d8-47d2-a59d-ce5ded79b63b
  Status: ACTIVE
  Flavor: g-a100-80gb-2022.x1

Server: vwn-gpu-2025-12-17-13-17-19-0
  ID: 4027da2e-c42b-411b-88f7-cc41f431959a
  Status: ACTIVE
  Flavor: g-a100-80gb-2022.x1
The servers property searches across all projects, making it useful for monitoring hypervisor workload.

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Relationship Traversal

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From Hypervisor to Servers to Users

Traverse relationships to understand who is using resources on a hypervisor: 
from myos.hypervisor import Hypervisor

hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk")

print(f"Analyzing hypervisor: {hypervisor.hostname}\n")
print(f"Status: {hypervisor.status}, State: {hypervisor.state}\n")

# Get all servers and their creators
servers = hypervisor.servers
print(f"Total servers: {len(servers)}\n")

user_server_count = {}

for server in servers:
    print(f"Server: {server.name}")
    print(f"  Status: {server.status}")
    print(f"  Image: {server.image.name}")
    
    # Get the user who created this server
    user = server.user
    print(f"  Created by: {user.name}")
    print(f"  User domain: {user.domain.name}")
    
    # Track servers per user
    if user.name not in user_server_count:
        user_server_count[user.name] = 0
    user_server_count[user.name] += 1
    print()

# Summary
print("User Summary:")
for username, count in user_server_count.items():
    print(f"  {username}: {count} server(s)")

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From Server to Hypervisor

Find which hypervisor is running a specific server: 
from myos.server import Server

server = Server(server_id="79b3b46d-c7d8-47d2-a59d-ce5ded79b63b")

# Get the hypervisor running this server
hypervisor = server.hypervisor

print(f"Server {server.name} is running on:")
print(f"  Hypervisor: {hypervisor.hostname}")
print(f"  HV Status: {hypervisor.status}")
print(f"  HV State: {hypervisor.state}")

# Get other servers on the same hypervisor
sibling_servers = hypervisor.servers
print(f"\nOther servers on this hypervisor ({len(sibling_servers) - 1}):")

for srv in sibling_servers:
    if srv.id != server.id:
        print(f"  - {srv.name} ({srv.status})")
This pattern is useful for understanding resource colocation and planning migrations.

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Capacity Planning Example

Monitor hypervisor utilization for capacity planning: 
from myos.hypervisor import Hypervisor

hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk")

print("=" * 60)
print(f"Hypervisor Capacity Report: {hypervisor.hostname}")
print("=" * 60)

# Health check
print(f"\nHealth Status:")
print(f"  Status: {hypervisor.status}")
print(f"  State: {hypervisor.state}")

# Get all servers
servers = hypervisor.servers

print(f"\nWorkload Summary:")
print(f"  Total Servers: {len(servers)}")

# Count servers by status
status_counts = {}
for server in servers:
    status = server.status
    if status not in status_counts:
        status_counts[status] = 0
    status_counts[status] += 1

for status, count in sorted(status_counts.items()):
    print(f"    {status}: {count}")

# Analyze flavors in use
print(f"\nFlavor Distribution:")
flavor_counts = {}

for server in servers:
    flavor_name = server.flavor.name
    if flavor_name not in flavor_counts:
        flavor_counts[flavor_name] = 0
    flavor_counts[flavor_name] += 1

for flavor, count in sorted(flavor_counts.items(), key=lambda x: x[1], reverse=True):
    print(f"  {flavor}: {count} server(s)")

# List active servers
active_servers = [s for s in servers if s.status == "ACTIVE"]

print(f"\nActive Servers ({len(active_servers)}):")
for server in active_servers[:10]:  # Show first 10
    user = server.user
    print(f"  - {server.name}")
    print(f"    Owner: {user.name} ({user.domain.name})")
    print(f"    Flavor: {server.flavor.name}")

print("\n" + "=" * 60)

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Multi-Hypervisor Analysis

Compare workloads across multiple hypervisors: 
from myos.hypervisor import Hypervisor

hypervisor_names = [
    "hv300.nubes.rl.ac.uk",
    "hv-a100x8-8.nubes.rl.ac.uk",
]

print("Multi-Hypervisor Workload Report\n")
print(f"{'Hypervisor':<40} {'Status':<10} {'State':<10} {'Servers':<10}")
print("=" * 70)

total_servers = 0

for hv_name in hypervisor_names:
    hv = Hypervisor(name=hv_name)
    server_count = len(hv.servers)
    total_servers += server_count
    
    print(f"{hv.hostname:<40} {hv.status:<10} {hv.state:<10} {server_count:<10}")

print("=" * 70)
print(f"{'Total':<40} {'':<10} {'':<10} {total_servers:<10}")
Querying multiple hypervisors and their servers can be slow. Consider caching results for dashboards.

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Complete Example

Here’s a comprehensive example for hypervisor monitoring: 
from myos.hypervisor import Hypervisor
from myos.cloud import Cloud

# Initialize with admin cloud
admin_cloud = Cloud(cloud="admin")
hypervisor = Hypervisor(name="hv-a100x8-8.nubes.rl.ac.uk", cloud=admin_cloud)

print("=" * 60)
print(f"Hypervisor Details: {hypervisor.hostname}")
print("=" * 60)

# Basic information
print(f"\nIdentification:")
print(f"  ID: {hypervisor.id}")
print(f"  Hostname: {hypervisor.hostname}")

# Health status
print(f"\nHealth:")
print(f"  Status: {hypervisor.status}")
print(f"  State: {hypervisor.state}")

if hypervisor.status == "enabled" and hypervisor.state == "up":
    print("  ✓ Hypervisor is healthy")
else:
    print("  ⚠ Hypervisor requires attention")

# Workload analysis
servers = hypervisor.servers
print(f"\nWorkload:")
print(f"  Total Servers: {len(servers)}")

active_count = len([s for s in servers if s.status == "ACTIVE"])
print(f"  Active Servers: {active_count}")

# Detailed server list
if servers:
    print(f"\nServer Details:")
    for server in servers[:5]:  # First 5 servers
        print(f"\n  {server.name}:")
        print(f"    Status: {server.status}")
        print(f"    Flavor: {server.flavor.name}")
        print(f"    Image: {server.image.name}")
        print(f"    Owner: {server.user.name}")

print("\n" + "=" * 60)

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Cloud Configuration

Hypervisor operations typically require admin credentials: 
from myos.hypervisor import Hypervisor
from myos.cloud import Cloud

# Use default cloud (may require admin)
hypervisor = Hypervisor(name="hv300.nubes.rl.ac.uk")

# Use specific admin cloud configuration
admin_cloud = Cloud(cloud="admin")
hypervisor = Hypervisor(name="hv300.nubes.rl.ac.uk", cloud=admin_cloud)
Ensure your cloud configuration has sufficient privileges to query hypervisor information.

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