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Introduction

Terminology

What is a Cloud?

What is a Cloud?

Traditional Solution to Infrastructure

traditional-hardware

Good Performance – Cloud Solution

scalable-cloud-model

CAPEX vs. OPEX

Cloud Computing Concepts

Cloud Computing Concepts (Cont.)

Cloud Architecture
Service Models

Service Models

IaaS: Infrastructure as a Service

  • Usage
    • Predefined shapes of compute instances (e.g. micro, small, large, extra-large)
      • for example: RedHat 7.8, 613 MB of memory, 1 TB block storage
    • Pay-per-use – pay for resources you use (time or amount)
      • no up-front costs
  • IaaS Services Examples
    • Load balancer
    • Autoscaling
    • Connectivity with on-premise network
    • Resource monitoring
  • IaaS providers
    • Amazon EC2, GoGrid, Rackspace, OpenNebula, Google Cloud, Oracle OCI, ...

PaaS: Platform as a Service

  • Usage
    • Choose software platform, e.g., JEE, .NET, Python, etc.
    • Pay-per-use – pay for the resources you use; no up-front costs
    • Cloud native, microservices, containers
  • PaaS features
    • Serverless
    • Auto Scalling and Load balancing
    • Local development environment
    • Administration API
  • PaaS providers
    • Google App Engine – first PaaS service
    • Today, mostly Kubernetes, Google, Heroku, Azure, AWS, Oracle

SaaS: Software as a Service

  • Software delivery model for applications hosted in the cloud
    • typically software for end-users
    • services accessed using a web browser
    • provides API for programmatic access
  • SaaS characteristics
    • Typically build on top of IaaS or PaaS
    • Configurable and customizable modern Web applications
    • Usually basic version for free, need to pay for "pro" version
    • Global availability - any computer, any device
    • Easy management - automatic and fast updates
    • Pay-per-use – pay for the time you use
  • SaaS providers
    • Google Apps, Salesforce, ...
Multitenancy

Multitenancy

  • Architectural approach where resources are shared between multiple tenants or consumers
  • Implications
    • Centralization of infrastructure in locations with lower costs
    • Peak-load capacity increases
    • Utilisation and efficiency improvements for systems that are not well utilised
  • Sharing options
    • Shared Everything
    • Shared Infrastructure
      • Virtual Machines
      • OS "virtualization"

Shared Everything

  • Resources are shared between all tenants or consumers
    • tenant: a service consumer
  • Common for the SaaS model
  • The application should provide tenant isolation
  • Data for multiple tenants is stored in the same database tables

Shared Infrastructure: Virtual Machines

  • Infrastructure shared via virtual machines
    • each tenant has its own virtual environment
    • Isolation provided by hypervisor
      • hypervisor: virtual machine manager, runs virtual machines
    • Resource contention depends on VM capability and configuration
    • Adds an additional layer and processes to run and manage

Shared Infrastructure: OS Virtualization

  • Infrastructure shared via OS Virtualization
    • Each tenant has its own processing zone
    • Isolation provided by the operating system
    • Resource contention depends on zone configuration
    • No VMs to run and manage, no abstraction layer between app & OS
Infrastructure as a Service

Overview

Region

Datacenters

Off-box Network Virtualization

Networking

Virtual Cloud Network

  • VCN = a private network in a single region in which your instances reside
  • A a single and contigous IPV4 CIDR block of your choice
    • CIDR (classless inter-domain routing) notation
    • IP address:
      • network prefix (the most significant bits) and
      • interfaces on the network (least significant bits) ~ network hosts
    • Example: 192.168.1.0/24
      • IP range: 192.168.1.0 - 192.168.1.255
  • You further create subnets on a VCN to organize your instances
    • The subnets must be "within" the VCN, they can span across ADs
    • Example: using 27 bits for a subnet mask allow for 8 subnets
      • 192.168.1.0/27, 192.168.1.32/27, 192.168.1.64/27, ...
      • Each subnet can have 32 hosts

VCN Routing and Security

  • Private and Public subnets
    • Public can communicate in/out from/to Internet
    • Internet traffic routed to public subnet
    • Private can be completely isolated or communicate to Internet only
  • Route tables
    • Required to route across subnets and in/out from the Internet
  • Security
    • Control access to/from the subnet

Peering

  • Local Peering
    • Connecting two VCNs in a region
  • Remote Peering
    • Connecting two VCNs across regions
  • Connectivity with on-premise datacenter
    • Fast connection needs to be in place
    • Secure VPN needs to be established
Compute

Compute Instances

  • Shape = amount of memory and CPU an instance is using
    • There are classes of shapes that you can choose from
    • Standard and HPC/GPU shapes
  • Virtual Machine (VM) – multi-tenant model
    • A hypervisor to virtualize the underlying Bare Metal server into smaller VMs
  • Bare Metal (BM) – single-tenant model
    • Direct hardware access, full bare metal server
    • Types of workloads: performance intensive, require a specific hypervisor
  • Dedicated VM Hosts (DVM) – single-tenant model
    • VM instances running on dedicated single-tenant servers
    • Not shared with other customers
  • States: start, stop, reboot, terminate
    • Billing pauses in STOP state but depends on shape

Image

  • Image
    • A template of a virtual hard drive with OS
    • Other software, libraries, configurations, etc.
  • Stored on a boot volume
  • Base images are provided
    • CentOS, Ubuntu, Windows Server, Oracle Linux, RedHat, etc.
    • Some may require licence costs
  • Custom images
    • You can create a custom image from the base image
    • Specific packages, libraries or custom configuiration
    • You store the image in the object storage

Autoscaling

  • Instance configuration
    • OS image, metadata, shape, vNICs, storage, subnets
    • Apply configuration to multiple instances at the same time
      • You can manage them all together (start, stop, terminate)
  • Autoscaling
    • Automatically adjust a number of compute instances in an instance pool
    • Control using performance metrics such CPU or memory utilization
    • cooldown period – time between scale in and scale out (e.g. 300 seconds)

Load Balancer

  • Managed service
    • Health check – checks health status of backends (TCP, HTTP)
    • Algorithm – round-robin, IP hash, least connections
  • Supports protocols
    • TCP, HTTP 1.1, HTTP/2, WebSocket, SSL termination, end-to-end SSL
    • Supports sticky sessions (sessions persistence)
  • High Availability
    • Primary and stand-by LB
    • Each LB is in different AD
    • Failover uses floating IP
Storage

Object Storage

  • Types of data to store
    • Storage for unstructured data (images, media files, logs, backups)
    • Data managed as objects, provides API using HTTP verbs
  • Namespace
    • Logical entity that serves as top-level container for all bueckts and objects
    • Each tenancy is provided one unique namespace
  • Bucket
    • A logical container for storing objects
    • Bucket names must be unique within tenancy
    • Hot bucket – standard, can be accessed immediatelly
    • Cold bucket – rarely accessed data, need to be restored
      • Minimum retention, such as 90 days
      • Time to First Byte (TTFB) is in hours, e.g. 4 hours
  • Object and metadata
    • data managed as objects regardless data type
  • Example object URL path:
    • /n/<namespace>/b/<bucket>/o/<object_name>

Block Storage

  • Local NVMe SSD device
    • Locally attached device, provided by some shapes, 200K IOPS - 1M IOPS
    • Workloads that require high storage performance
    • usually no RAID, snapshots, backups
  • Block volumes
    • Reside in storage servers
    • NVMe SSD based, up to 35K IOPS
    • Data stored on block volumes beyond the lifespan of compute instance
    • Multiple replicas across multiple storage servers
  • File Storage
    • Network file server (NFS)
    • Client mounts a mount target (NFS endpoint) and an export path
    • Example
      • sudo mount 10.0.0.6/example1/path /mnt/mountpointA
Infrastructure as Code

Overview

  • Definition
    • Application envs (in a cloud) managed via definition files
    • Version control, team development, scripting, etc.
  • Major Technologies
    • Configuration Management Tools
      • install and manage software on machines that already exist
      • Examples: Ansible, Chef, Puppet
    • Abstraction of cloud infrastructure
      • Terraform

Terraform

  • Higher-level abstraction of the datacenter and associated services
  • Supports many service providers
    • Google, Microsoft, Oracle, AWS
  • Steps
    1. Description of resources in Hashicorp Configuration Language (HCL)
      • instances, networks, firewall rules, routing tables, etc.
    2. Terraform generates execution plan to reach the desired state
    3. Terraform executes the plan to reach the desired state; can generate incremental execution plan