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The Cloud class is the main entry point for interacting with your OpenStack infrastructure using myos. It provides a unified interface to access all OpenStack resources including hypervisors, flavors, images, projects, and floating IPs.

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Overview

The Cloud class acts as a gateway to your OpenStack cloud, wrapping OpenStack CLI commands and returning resource objects that you can work with programmatically.

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Key Features

  • Unified Access: Single interface to access all OpenStack resources
  • Lazy Loading: Resources are loaded on-demand when you access properties
  • EntityList Support: All resource collections return EntityList objects with built-in filtering, sorting, and mapping
  • Cloud Context: Automatically passes cloud authentication to all resource objects

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Basic Usage

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Creating a Cloud Instance

from myos.cloud import Cloud

# Connect to the default 'admin' cloud
cloud = Cloud()
The cloud parameter corresponds to the cloud name in your OpenStack CLI configuration (see Authentication).

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Accessing Resources

The Cloud class provides property-based access to different resource types. Each property returns an EntityList containing resource objects.

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Available Resources

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Hypervisors

Access all hypervisors in your cloud: 
cloud = Cloud("admin")
hypervisors = cloud.hypervisors

print(f"Total hypervisors: {len(hypervisors)}")

for hv in hypervisors:
    print(hv.hostname)

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Flavors

Retrieve all available instance flavors: 
flavors = cloud.flavors

# Find large flavors
large_flavors = flavors.filter(lambda f: 'large' in f.name.lower())
The flavors property fetches all flavors including private ones using the --all flag.

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Images

Get all images available in the cloud: 
images = cloud.images

for image in images:
    print(f"Image: {image.id}")

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Projects

Access all projects (tenants): 
projects = cloud.projects

for project in projects:
    print(f"Project: {project.name} (ID: {project.id})")

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Floating IPs

Retrieve all floating IP addresses: 
fips = cloud.fips

print(f"Total floating IPs: {len(fips)}")

for fip in fips:
    print(fip.ip)

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How It Works

The Cloud class uses the OpenStack CLI under the hood. When you access a resource property, myos:
  1. Constructs an OpenStack CLI command with the appropriate --os-cloud parameter
  2. Executes the command and captures JSON output
  3. Parses the JSON and creates resource objects
  4. Returns an EntityList containing all resources

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Example Internal Flow

When you call cloud.hypervisors, myos executes: 
openstack --os-cloud admin hypervisor list --format json
The JSON response is parsed and Hypervisor objects are created for each entry.
The Cloud class requires the OpenStack CLI to be installed and properly configured. See Authentication for setup instructions.

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Working with EntityLists

All resource properties return EntityList objects, which support functional programming patterns: 
from myos.cloud import Cloud

cloud = Cloud("admin")

# Get all hypervisors
hypervisors = cloud.hypervisors

# Filter by hostname pattern
filtered = hypervisors.filter(lambda hv: 'gpu' in hv.hostname)

# Sort by hostname
sorted_hvs = filtered.sort(lambda hv: hv.hostname)

# Map to just hostnames
hostnames = sorted_hvs.map(lambda hv: hv.hostname)
EntityList objects support chaining, allowing you to combine filter, sort, and map operations elegantly.

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Complete Example

Here’s a complete example that demonstrates accessing multiple resource types: 
from myos.cloud import Cloud

# Initialize cloud connection
cloud = Cloud("admin")

# Get resource counts
print("=== Cloud Resources ===")
print(f"Hypervisors: {len(cloud.hypervisors)}")
print(f"Flavors: {len(cloud.flavors)}")
print(f"Images: {len(cloud.images)}")
print(f"Projects: {len(cloud.projects)}")
print(f"Floating IPs: {len(cloud.fips)}")

# Work with specific resources
projects = cloud.projects
for project in projects:
    servers = project.servers
    if len(servers) > 0:
        print(f"\nProject '{project.name}' has {len(servers)} servers")

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Source Reference

The Cloud class implementation can be found in cloud.py:5-83. Each resource property follows a consistent pattern:
  • Execute OpenStack CLI command with --os-cloud parameter
  • Parse JSON response
  • Create resource objects
  • Return EntityList

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Next Steps

  • Learn about Authentication to configure cloud access
  • Explore individual resource classes like Hypervisor, Project, and Server
  • Understand EntityList methods for filtering and transforming data

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