Cloud computing

Once upon a time...

Infrastructure used to be hosted on-premises (and still is in many cases)
Some advantages…

• Under your team's supervision
• More control over security
  
  But more disadvantages…
• Breakdowns? Your responsibility!
• Keeping everything up-to-date? Your responsibility!
• Managing access? Your responsibility!
• Need more space (scaling)? Guess what… your responsibility!

Nowadays...

Infrastructure on-premises still exists, but gets less common every year
Cloud computing: allocation of one, several or all parts of your infrastructure to the management of a third party
Biggest advantage: less responsibilities, so less worries

3 main types of cloud computing 'as a Service'

• Infrastructure as a Service (IaaS)
• Platform as a Service (PaaS)
• Software as a Service (SaaS)

IaaS vs. PaaS vs. SaaS

Infrastructure as a Service (IaaS)

• Third party provides you with infrastructure services, like storage and virtualization, as you need them, via a cloud, through the internet
• You provide: operating system, data, applications, middleware and runtimes
• No on-site datacenter anymore
• Access and control of infrastructure using an API or dashboard
• Big flexibility: scaling up or down easily
• Low overhead and no maintenance cost
  
  
• Public cloud providers: AWS, Microsoft Azure, Google Cloud, etc.
  

Platform as a Service (PaaS)

• One step further than IaaS
• You provide: data and applications
• Provider hosts the hardware and software
• You write the code, build, and manage your apps, but you do it without the headaches of software updates or hardware maintenance
  
  
• PaaS providers: AWS Elastic Beanstalk, Heroku, Red Hat OpenShift, etc.
  

Software as a Service (SaaS)

• Cloud application services
• Delivering an entire application that is managed by a provider, via a web browser
• Software updates, bug fixes, and general software maintenance handled by provider
• Users connect to the app using an API or dashboard
• No installation of the software on individual machines
• Ideal for small businesses because of relatively low cost
  
  
• SaaS providers: Dropbox, Salesforce, Google Apps, Red Hat Insights, etc.
  

Scalability and Elasticity

Vertical or horizontal scaling

• Scaling up / vertical scaling: adding more resources (additional CPU, memory, etc.) to an instance that already has resources allocated, or removing resources
  • Not always easy: often requires a redeployment of an instance or powering down to make the change
    
    
• Horizontal scaling: add additional instances that can handle the workload (extra VMs, container pods, etc.)
  • Distribution of users over instance: using a load balancer which will choose the instance the user will connect with
  • Advantage over vertical scaling: no need to make changes to the virtual hardware on each machine, but rather add and remove capacity from the load balancer itself

Load balancing

Load balancer:

• Will distribute the incoming traffic over the available servers (acts as a reverse proxy)
• Similar to a traffic cop at a crossroads
• Goal:
  • Make the overall processing more efficient
  • Optimize the response time
  • Avoid overloading of instances

Elasticity

Elasticity: the workload’s ability to scale up and down

• Static scaling: provisioning resources to account for the “peak” even though the underlying workload is constantly changing
• Elastic scaling: allow for the resources to be added on demand, while ensuring some buffer room
  • Big advantage: only pay for what you need