Cloud
Public, private and hybrid clouds
Private cloud: servers hosted within an organization’s own data center or managed by a vendor on behalf of a single customer. Servers in a private cloud are single-tenant, not shared with other customers as in a public cloud.
Hybrid Cloud: A combination of public and private clouds useful when migrating from local servers or handling peak loads. Operating two distinct cloud presences in tandem increases complexity more than proportionally.
Public Cloud: The term “public cloud” is a bit unfortunate, representing false connotations. Customers of public clouds are isolated from each other by multiple layers of hardware and software virtualization. A private cloud offers little or no practical security benefit over a public cloud.
Regions and Zones
Pithy
Region: a location where a cloud provider has data centers
us-east-1
Zone: a data center within a regiona-Z
Serverless functions
Traditional web server:
- HTTP requests are forwarded by the networking stack of the OS to a web server
- When the response completes the web server continues to wait for requests
Serverless function example:
- an HTTP request arrives
- it triggers a cloud function to handle the response
- when complete the function terminates, the owner pays for the time of execution
Providers
AWS
Spot instances pay a discounted rate for otherwise spare capacity. AWS can interrupt your spot instance, which is why it’s cheaper.
Digital Ocean
Super cheap, droplets (virtual machines) all come with a public IP and start at 4$