feat: add module 9

Author: sergkudinov

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+---
+duration: 3 hours
+---
+
+# Cloud-native applications. Microservice architecture | with Istio
+
+Cloud-native is a term used to describe container-based environments. Cloud-native technologies are used to develop applications built with services packaged in containers, deployed as microservices, and managed on elastic infrastructure through agile DevOps processes and continuous delivery workflows.
+
+[Cloud Native Computing Foundation (CNCF)](https://www.cncf.io/), [launched](https://www.cncf.io/announcements/2015/06/21/new-cloud-native-computing-foundation-to-drive-alignment-among-container-technologies/) in 2015 by the Linux Foundation.
+
+## What is Cloud?
+
+- remote data centers
+- offers software or hardware to a business or individual
+- you can access it through the Internet
+
+## Why business is moving to the Cloud?
+
+- **Flexibility and agility**   
+  Cloud computing makes it easy to quickly scale up/down the capacity.
+- **Security**   
+  Implement effective disaster recovery solutions without large, upfront investments.
+- **Automatic software and hardware updates**   
+  The servers are maintained by your supplier.
+- **Saves money on hardware, “pay as you go”**
+- **Increased collaboration**   
+  Team members can work anywhere.
+- **Сompetitive advantage**   
+  Small businesses have access to enterprise-class technology they couldn’t afford on their own.
+
+[Read more](https://www.pointclick.net/moving-to-the-cloud/)
+
+## Choose your service model
+
+- How much you can and want **to manage yourself**?
+- How much you want **your service provider to manage**?
+
+![Cloud service models](image/aaS.jpg)
+
+Match services yourself: DigitalOcean, Wix, Heroku, Shopify, Amazon Web Services (AWS), Salesforce, Google Cloud Platform (GCP), GitHub, Youtube, GitLab, Travis CI, IBM cloud, Trello.
+
+[Read more](https://www.bmc.com/blogs/saas-vs-paas-vs-iaas-whats-the-difference-and-how-to-choose/_)
+
+## What are cloud-native applications?
+
+Cloud-native applications are:
+- a collection of small, independent, and loosely coupled services
+- providing a consistent development and automated management
+- designed to run in the cloud.
+
+**Key attributes of cloud-native:**
+
+1. Packaged as lightweight **containers**
+2. Developed with best-of-breed **languages and frameworks**
+3. Designed as **loosely coupled microservices**
+
+**Other attributes:**
+
+4. **Centered around APIs** for interaction and collaboration
+5. **Architected** with a clean separation of **stateless and stateful** services
+6. **Isolated** from the server and operating system dependencies
+7. **Deployed** on self-service, elastic, cloud infrastructure
+8. **Managed** through agile DevOps processes   
+  Each service has an independent life cycle and CI/CD.
+9. **Automated** capabilities
+10. Defined, policy-driven resource allocation
+
+[Read more](https://thenewstack.io/10-key-attributes-of-cloud-native-applications/)
+
+## Monolithic vs Microservices architecture
+
+![Monolithic vs Microservices architecture](image/monolithic-vs-microservices.jpg)
+
+**Microservices** - a style that structures an application as a collection of services that are:
+
+- highly maintainable and testable
+- [loosely coupled](https://en.wikipedia.org/wiki/Loose_coupling)
+- independently deployable
+- organized around business capabilities
+- owned by a small team
+- sourced as a separate Git repo with its tests
+
+**Monolithic** - a style where a single-tiered software application in which different components are combined into a single program from a single platform.
+
+## Microservices are NOT
+
+1. Your SOA (service-oriented architecture) cut into services
+
+2. Anything involving a large framework   
+  What part of "micro" are folks missing?
+
+3. Development patterns where you deploy things into containers   
+  You want containers,  do containers. Fine with me. Deployment decisions have nothing to do with microservices. If you're coupling your code to the architecture that tightly, re-read #2.
+  
+4. Things with some cool language   
+  Once again, if you like cool languages, use them. Sounds fun. It's just has nothing to do with microservices.
+  
+5. Systems with thousands of little tiny pieces of code scattered all over the place making it impossible to reason about anything
+  You're loving the idea to death. You've gone too far the other way. Both the "micro" and "service" part are equally important.
+
+[Reference](https://danielbmarkham.com/honest-microservices/)
+
+## Application centered around APIs
+
+![Application centered around APIs](image/api.jpg)
+
+## Service mesh
+
+**Service mesh** - an infrastructure layer for facilitating service-to-service communications between microservices, often using a **sidecar proxy**.
+
+**Provides:**
+
+  - Connection between microservices
+  - Monitoring, observability into communications
+  - Securing
+  - Managing
+
+![Service mesh](image/service-mesh.jpg)
+
+## Service mesh architecture
+
+![Service mesh architecture](image/sm-architecture.jpg)
+
+Platforms implementing service mesh:
+
+  - **Istio**
+  - Consul
+  - Linkerd
+
+## Service mesh example
+
+![Service mesh example](image/sm-bookinfo.jpg)
+  
+## Real large examples of service mesh 
+
+![Real big service mesh examples](image/sm-amazon-netflix.jpg)
+
+## Istio
+
+**Istio** - a platform that implements service mesh (provides a uniform way to secure, connect, and monitor microservices).
+
+![Istio architecture](image/istio.jpg)
+
+## What can you do with Istio?
+
+Istio provides operational requirements:
+
+- canary rollout (deployment)
+- A/B testing
+- rate-limiting
+- access control
+- end-to-end authentication

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+
+# Lab
+
+## Objectives
+
+1. Quickstart with Istio
+2. Route requests
+3. Traffic shifting (canary rollout)
+
+## Before starting
+
+1. Install Minikube and start a Kubernetes cluster
+
+After Minikube installation run:
+
+- `minikube config set vm-driver virtualbox` (or `vmware`, or `kvm2`)
+- `minikube start --memory=16384 --cpus=4 --kubernetes-version=v1.18.0`
+
+> **Note!** If you don’t have enough RAM to allocate to the minikube virtual machine then try to put the maximum you have on your laptop.
+
+Reference - https://istio.io/docs/setup/platform-setup/minikube/
+
+## 1. Quick start with Istio
+
+This task lets you quickly evaluate Istio.
+
+Instructions - https://istio.io/docs/setup/getting-started/
+
+Do everything until [Next steps](https://istio.io/docs/setup/getting-started/#next-steps) section.
+
+**Results:**
+
+- running [Bookinfo example application](https://istio.io/docs/examples/bookinfo/) and available at `http://$GATEWAY_URL/productpage` (where $GATEWAY_URL - is the specific IP and PORT for every deployment)
+- running [Kiali dashboard](https://kiali.io/) with an overview of your mesh with the relationships between the services
+
+![Kiali dashboard](image/kiali-example2.jpg)
+
+## 2. Request Routing
+
+This task shows you how to route requests dynamically to multiple versions of a microservice.
+
+Instructions - https://istio.io/docs/tasks/traffic-management/request-routing/
+
+**Results:**
+
+- sending 100% of the traffic to the `v1` version of each of the Bookinfo services
+- setting a rule to selectively send traffic to version `v2` of the reviews service based on a custom `end-user` header
+
+## 3. Traffic Shifting (canary rollout)
+
+This task shows you how to gradually migrate traffic from an older version to a new version.
+
+Instructions - https://istio.io/docs/tasks/traffic-management/traffic-shifting/
+
+**Results:**
+
+- migrating traffic from an old to new version of the `reviews` service using Istio’s weighted routing feature