Chapter 6 Deployment Strategies

Question 1

How does continuous delivery extend CI?

Answer 1

Continuous delivery expands upon continuous integration by deploying all code changes to a testing environment and/or a production environment after the build stage. When properly implemented, developers will always have a deployment-ready build artifact that has passed through a standardized test process.

Question 2

How does continuous deployment extend continuous delivery?

Answer 2

It is the automated release of software to customers, from check in through production.

Question 3

Elastic Load Balancing and _____ are designed to work together.

Answer 3

Auto Scaling

Question 4

Components required for scalability and availability

Answer 4

1. Multi AZ and multi region
2. Health Check and failover
3. Stateless applications that store state in cache/DB
4. AWS services (i.e. auto scaling)

Question 5

What are 3 of the core underlying technologies used by Elastic Beanstalk?

Answer 5

1. EC2
2. ELB
3. Auto Scaling

Question 6

Pre-configured options for Elastic Beanstalk

Answer 6

1. Single-instance (development, low cost)

2. Load balanced, AWS Auto Scaling (production)

Question 7

What is required to deploy an Elastic Beanstalk application?

Answer 7

A ‘source bundle’. This can come from a source repository (i.e. CodeCommit, BitBucket) or S3 bucket.

Question 8

T/F: Each Elastic Beanstalk environment is a separate version of the application, and that version’s AWS Cloud components deploy onto AWS resources to support that version. Each environment runs one application version at a time, but you can run multiple environments, with the same application on each, along with its own customizations and resources.

Answer 8

True

Question 9

In Elastic Beanstalk, to launch an environment you must first choose a/an _____.

Answer 9

environment tier

The environment tier designates the type of application that the environment runs, and determines what resources Elastic Beanstalk provisions to support it. An application that serves HTTP requests runs in a web server environment tier. An environment that pulls tasks from an Amazon Simple Queue Service (Amazon SQS) queue runs in a worker environment tier.

Question 10

Where are Elastic Beanstalk configuration files stored? What is the file format?

Answer 10

Stored in the ‘.ebextensions’ directory of your web application. The format is YAML (or JSON), and the file extension is ‘.config’

Question 11

Environment

Answer 11

An environment is a collection of AWS resources running an application version.

Question 12

How to modify application stack in Beanstalk without introducing unrecoverable failures?

Answer 12

Use the Elastic Beanstalk service and ebextensions to make modifications instead of CloudFormation

Question 13

What is a deployment in the context of EC2 instances?

Answer 13

process of copying content and executing scripts on instances in your deployment group

Question 14

all-at-once deployment

Answer 14

applies update to all instances at once. Involves downtime

Question 15

in-place deployment

Answer 15

CodeDeploy stops application on target instance, deploys, validates. Works well if you have a load balancer (no downtime).

FYI in-place deployments not available for AWS Lambda.

Question 16

rolling deployment

Answer 16

With rolling deployments, Elastic Beanstalk splits the environment’s EC2 instances into batches and deploys the new version of the application to one batch at a time, leaving the rest of the instances in the environment running the old version of the application. During a rolling deployment, some instances serve requests with the old version of the application, while instances in completed batches serve other requests with the new version.

Question 17

what is ‘rolling with batch’ deployment

Answer 17

Elastic Beanstalk related. Under this option, when applying a rolling deployment, a new batch of instances is launched before you take instances out of service for rolling updates. These batches are used for potential rollbacks from a failed update. After the deployment is complete, these instances are terminated.

Question 18

green/blue deployment

Answer 18

running environment is blue, new environment with update is green. When changes complete and tested in green, swap CNAMEs of environments to redirect traffic flow.

• Zero downtime.
• Lambda uses this.
• Not a good idea with RDS without snapshot backups

Question 19

immutable deployment

Answer 19

when you need to replace instances in deployment (new VMs). Code deployed to new instances.

Instead of roll back process in event of failed health check (i.e. rolling deployments), you simply terminate an auto scaling group.

Question 20

Metrics with Elastic Beanstalk

Answer 20

Not charged for default metrics, since they are published to Cloudwatch.

Custom metrics can be enabled via CloudWatch

Question 21

Environment

Answer 21

An environment is a collection of AWS resources running an application version.

Question 22

environment tier

Answer 22

environment tier designates the type of application that the environment runs, and determines what resources Elastic Beanstalk provisions to support it. An application that serves HTTP requests runs in a web server environment tier. An environment that pulls tasks from an Amazon Simple Queue Service (Amazon SQS) queue runs in a worker environment tier.

Question 23

Application version

Answer 23

In Elastic Beanstalk, an application version refers to a specific, labeled iteration of deployable code for a web application. An application version points to an Amazon Simple Storage Service (Amazon S3) object that contains the deployable code, such as a Java WAR file.

Question 24

How to record and track environment and instance health over time within Elastic Beanstalk?

Answer 24

Configure your environment to publish the information gathered by Elastic Beanstalk for enhanced health reporting to Amazon CloudWatch as custom metrics. This involves charges.

Question 25

What is only metric for which there is no charge in Elastic Beanstalk?

Answer 25

Environment Health

Question 26

What OS options does Elastic Beanstalk support?

Answer 26

Amazon Linux and Windows Server

Question 27

What is a service role

Answer 27

a role that an AWS service assumes to perform actions on your behalf.

Question 28

How does Elastic Beanstalk pricing work?

Answer 28

There are no charges for using Elastic Beanstalk. But the underlying services which are composed by the service (RDS, EC2, etc.) are charges at normal rates.

Question 29

What happens the an environment’s RDS database if the environment is deleted?

Answer 29

The database is deleted as well. You need a snapshot to retain and restore it.

Question 30

rolling deployment with an additional batch

Answer 30

To maintain full capacity during deployments, you can configure your environment to launch a new batch of instances before taking any instances out of service.