Section 14 - Devops

Question 1

What is CI / CD?

Answer 1

• Software development best practice
  
  • Continous integration, Continous delivery / Deployment
• Make Small Changes & Automate Everything
  
  • Small, Incremental code changes, Automate as much as possible
  • e.g. code integration, build, test , deployment

Question 2

AWS Developer Tools?

Answer 2

• CodeCommit (Source & version Control)
  
  • Source control service enabling teams to collaborate on code.
• CodeBuild (Automated Build)
  
  • Compiles source code, runs tests and produces packages that are ready to deploy.
• CodeDeploy(Automated Deployment)
  
  • Automates code deployments to any instance, including EC2, Lambda and on-premises.
• CodePipeline(Manages The workflow)
  
  • End-to-end solution, build,test, and deploy your application everytime there is code change.

Question 3

What is CodeDeploy?

Answer 3

• Automated Deployment
• EC2 Instances, on-premises & Lambda
• Quickly release new features
• Avoid downtime during deployments
• CodeDeploy Deployment Approaches
  
  • In-Place
    
    • The application is stopped on each instance and the new release is installed. Also known as a Rolling Update
    • Capacity is reduced during the deployment.
    • Lambda is not supported.
    • Rolling back invloves a re-deploy
    • Greate when deploying the first time.
  • Blue / Green​ (Safest Option)
    
    • ​New instances are provisioned and the new release is installed on the new instances.
    • Blue represents the active deployment,
    • Green is the new release.
    • No capacity reduction.
    • Green instances can de created ahead of time.
    • Easy to switch between old and new.
    • You pay for 2 environments until you terminate the old servers.

Question 4

Example In-Place Deployment?

Answer 4

• The application is stopped on the first instance.
• The instance will be out of service during the deployment so capacity is reduced.
• You should configure your Elastic Load balancer to stop sending requests to the instance.
• CodeDeploy installs the new version, known as Revision.
• The instance comes back into service.
• How to Roll Back? You’ll need to re-deploy the previous version which can be time consuming.

Question 5

Example Blue/Green Deployment?

Answer 5

• Blue represents the current version of our application.
• CodeDeploy provisions new instances. (Step 1)
• The new Revision is deployed to the Green envrionment.(Step 2)
• The Green instances are registered with the Elastic Load balancer. (Step 3)
• Traffic is routed away from the old environment.(Step 4)
• The Blue environment is evntually terminated (Step 5)
• How do you rollback? Just set the Load balancer to direct the traffic back to the original environment.

Question 6

CodeDeploy using the AppSpec File?

Answer 6

• Configuration File
  
  • Defines the parameters to be used during a CodeDeploy deployment
• EC2
  
  • For EC2 and on-premises systems, YAML Only.
• Lambda
  
  • YAML and JSON supported. File structure depends on wheather you are deploying to Lambda or EC2.

Question 7

EC2 AppSpec File Structure?

Answer 7

NB: The appspec.yml must be placed in the root of the directory of your Revision, otherwise the deployment will fail.

• Version
  
  • Reserved for Future USE
  • Currently the allowed value is 0.0
• OS
  
  • Operating system version
  • The operating system version you are using e.g Linux, Windows
• Files
  
  • Configuration Files, packages
  • The location of any application files that need to be copied and where they should be copied to.
• Hooks
  
  • Lifecycle event hooks
  • Scripts which need to run at set points in the deployment lifecycle.
  • Hooks have a very specific run order.

Question 8

CodeDeploy Lifecycle Event Hooks?

Answer 8

• Run Order
  
  • Lifecycle event hooks are run in a specific order known as the Run order.
• In-Place Deployment
  
  • Broadly 3 Phases: de-register, installaing, re-registering with a Load Balancer
• Logical Flow
  
  • For the exam you’ll need to understand the Logical Flow.

Question 9

What is CodePipeline?

Answer 9

A fully managed CI/CD service.

• Orchestrates Build,Test and Deployment
  
  • The pipeline is triggered every time there is change to your code.
  • a workflow must be defined for codepipeline
• Automated Release Process
  
  • ​Fast, consistent, fewer mistakes. Enables quick release of new features and bug fixes
• CodePipeline integrates with:
  
  • CodeCommit, CodeBuild, CodeDeploy, Github, Jenkins, Elastic Beanstalk, CloudFormation, Lambda, Elastic Container Service.

Question 10

What is Elastic Container Service?

Answer 10

• A container orchestration service which supports Docker and Windows Containers.
• Quickly deploy and scale containerized workloads without having to install, configure, manage and scale your own orchestration platform.
• Similar to Kubernetes, but with deep integration with AWS service e.g IAM, VPC, Route53
• Running options for ECS:
  
  • Clusters of Virtual Machines
    
    • ECS will run your containers on clusters of virtual machine
  • Fargate for serverless
    
    • Use Fargate for serverless containers and you don’t need to worry about the underlying EC2 instances!
  • EC2 for More Control
    
    • If you want to control the installation, configuration and management of your compute environment

Question 11

What is Elastic Container Registry (ECR)?

Answer 11

• Amazon Elastic Container Registry (Amazon ECR) is a fully managed container registry that makes it easy to store, manage, share, and deploy your container images and artifacts anywhere.
• Amazon ECR eliminates the need to operate your own container repositories or worry about scaling the underlying infrastructure

Question 12

Docker & and CodeBuild Exam Tips?

Answer 12

• Docker
  
  • docker build -t myexamplerepo .
  • docker tag myexamplerepo:latest 475745664.dkr.ecr.ue-centa-1.amazonaws.com ….:latest
  • docker push 475745664.dkr.ecr.ue-centa-1.amazonaws.com ….:latest
• “​buildspec.yml” File
  
  • Use buildspec.yml to define the build commands and settings used by CodeBuild to tun your build.
• Override “buildspec.yml” settings
  
  • You can override the settings in buildspec.yml by adding your own commands in the console when you launch the build.

Question 13

Elastic Beanstalk & Docker Containers?

Answer 13

• Elastic Beanstalk supports the deployment of Docker containers.
• Docker containers are self-contained and include all the configuration information and software your web application requires to run.
• Elastic Beanstalk handles the capacity provisioning, load balancing, scaling and application health monitoring.
• Deployment options:
  
  • Single Docker Container
    
    • You can either run a single Docker container on an EC2 instance provisioned by Elastic Beanstalk
  • Multiple Docker Containers
    
    • Use Elastic Beanstalk to build an ECS cluster and deploy multiple Docker containers on each instance
  • Deploy Your Code
    
    • Upload a zip file containing your code and bundle Elastic Beanstalk will do the rest.
    • Code can be uploaded directly from your local machine or a public S3 bucket.
    • You can also store your code in CodeCommit - But must use the Elastic Beanstalk CLI.
  • Upgrade Your Code
    
    • If you want to upgrade your application to a new version, it’s one easy step in the console to upload and deploy.

Question 14

What is CloudFormation?

Answer 14

• Infrastructure As Code
  
  • Cloud formation allows you to manage , configure , and provision AWS infrastructure as YAML or JSON code.
• Parameters
  
  • input custom values
• Conditions
  
  • e.g. Provision resources based on environment
• Resources
  
  • This section is manadory and describes the AWS resources that CloudFormation will create.
• Mappings
  
  • Allows you to create custom mappings like Region: AMI
• Transform
  
  • Allows you to reference code located in S3, e.g. Lambda code or resuable snippets of CloudFormation code.

Question 15

Serverless Application Model (SAM) ?

Answer 15

• Define and provision serverless applications using CloudFormation
• “sam package”
  
  • Packages your application and uploads to S3
• “sam deploy”
  
  • Deploys your serverless app using CloudFormation

Question 16

CloudFormation Nested Stacks?

Answer 16

• CloudFormation nested stacks enable re-use of CloudFormation Code for common use cases. e.g. Standard configuration for a load balancer, web server or application server.
• Instead of copying out the code each time, create a standard template for each common use case and reference from withon your CloudFormation template.
• CloudFormation Template reference:
  
  • Resource
    
    • Type: AWS::CloudFormation::Stack
  • Template must be hosted on S3
• You can have multi level stacks …but only one level is recommended