4 Cloud Computing Fundamentals
Learn how cloud computing works, how cloud services and infrastructure are organized, and how to plan for capacity, availability, and shared security responsibilities.
essentials
provides on-demand network access to a shared pool of resources, including servers, storage, networks, and applications. These resources can be quickly provisioned and released. Instead of buying and operating every resource, a customer can use resources supplied by a cloud provider.
Cloud services commonly have several related features:
: Users can provision resources when needed, often through a web console or API.
: Services are available over networks to different kinds of devices.
: A provider serves multiple customers using shared infrastructure while logically separating their resources.
: Capacity can expand or contract as demand changes.
: Usage can be monitored and billed according to the service’s terms.
Virtual machines (VMs) and containers are common ways to run software in the cloud. A VM runs its own operating system on virtualized hardware. A container packages an application and its dependencies while sharing the host operating system. These are technologies for delivering or running workloads, not cloud .
Service and
describe what the provider manages, while describe who the cloud infrastructure is for and how it is arranged. The two categories answer different questions, and a service model can be used with different .
The main are:
Infrastructure as a Service (IaaS): Customers have more control over virtual machines and operating systems.
Platform as a Service (PaaS): The provider manages more of the application platform.
Software as a Service (SaaS): Customers use an application operated by the provider.
The four are:
Public cloud: Infrastructure offered for use by the general public and operated by a cloud provider.
Private cloud: Infrastructure set aside for one organization. It can be hosted on-site or elsewhere and managed by the organization, a provider, or both.
Community cloud: Infrastructure for a specific group of organizations with shared concerns, such as security or compliance requirements.
Hybrid cloud: Two or more distinct cloud infrastructures connected to support data or application portability. For example, an organization might keep some systems in its private cloud while using public-cloud capacity for variable workloads.
Regions, zones, and
A region is a geographic area where a provider operates cloud infrastructure. Regions can differ in available services. An organization may select a region to reduce latency, meet data-location requirements, or support recovery planning.
A zone, called an Zone by some providers, is an isolated location within a region. The exact terminology and physical arrangements vary by provider.
is the ability of a service to remain usable when expected. Choosing a region or zone does not by itself make an application highly available; the application must be designed to withstand failures. An application running in a single zone remains exposed to a failure affecting that zone, while distributing suitable components across multiple zones can reduce that risk.
Recovery across regions can address some wider failures, but requires deliberate planning. This includes deciding how data is replicated and how traffic is redirected.
and elasticity
is the ability to increase or decrease capacity to handle changing workload demands. Two common approaches are:
Vertical scaling (scale up or down): Give one machine more or fewer resources, such as CPU or memory.
Horizontal scaling (scale out or in): Add or remove machines or instances to share the workload.
For example, a web application might add VM instances behind a load balancer during a traffic spike, then remove the extra instances afterward. Elasticity emphasizes adjusting capacity dynamically as demand changes.
Scaling can improve performance, but it does not automatically ensure . A scalable application can still depend on a single component that may fail.
Shared security responsibilities
Cloud security and operations involve responsibilities shared between the provider and the customer. The provider manages the cloud infrastructure it operates, while the customer remains responsible for duties assigned to them. Customer duties can include managing data, identities, access settings, and application configuration.
The exact division depends on the service and provider. Generally, the provider manages more of the underlying stack for SaaS than for IaaS, where customers typically manage more of the operating system and workload configuration. Using a cloud service does not automatically secure an application or its data.