Deployment strategies are a crucial facet of any software development project. When reviewing for the AWS Certified SysOps Administrator – Associate (SOA-C02) exam, understanding these strategies and their application in AWS services like AWS Elastic Beanstalk and AWS CodeDeploy is paramount. Primarily, three deployment strategies are widely recognized as industry standard – Blue/Green, Rolling, and Canary.
Blue/Green Deployment
With the Blue/Green deployment, two identical production environments (blue and green) are established. At any one time, only one environment is live. For instance, if the blue environment currently hosts the live application, the green environment is idle.
The development team prepares a new version of the application in the idle environment (green). After rigorous testing and validation, the router’s configuration is updated to redirect all incoming requests from the old environment (blue) to the new one (green).
In AWS, implementing Blue/Green deployments is achieved effortlessly using AWS CodeDeploy. CodeDeploy allows easy rerouting of production traffic from the existing environment (blue) to the newly launched environment (green) after tests have passed.
Advantages of Blue/Green deployment include nearly zero downtime during software rollouts and an instant rollback option if something goes wrong.
Rolling Deployment
Rolling deployment is another strategy which involves releasing new versions of an application in a staggered and controlled manner. The application is partitioned into subsets, often referred to as chunks or batches.
This strategy thrives in AWS Elastic Beanstalk service deployment. You update the application version to your environment, then Elastic Beanstalk will sequentially switch out instances with the new version.
The advantages of the Rolling deployment scenario are mitigated risk and reduced load on the system while deploying new versions.
Canary Deployment
Canary deployment is a strategy that routes a small subset of users to a new version of an application, while the rest of the users remain on the stable, existing version. The term ‘canary’ stems from the ‘canary in a coal mine’ analogy where birds were used to test the safety of mining conditions.
In AWS context, AWS CodeDeploy offers canary deployments. AWS Lambda and AWS API Gateway also provide native support. Typically, 5-10% of the total user base is selected to try out the new application version before making a decision to roll it out to the rest of the users.
The key advantage of Canary deployment scenarios lies in their risk mitigation especially when introducing substantial changes. This technique allows for better testing and detection of any potential issues with a new version before it affects all users.
| Deployment Type | Pros | Cons | AWS Services |
|---|---|---|---|
| Blue/Green | Nearly zero downtime, instant rollback | Requires double resources | AWS CodeDeploy, EC2, Elastic Load Balancing |
| Rolling | Reduces system load and risk | Possibility of different versions running at the same time | AWS Elastic Beanstalk |
| Canary | Enhanced risk mitigation, better testing | Requires high user volume, increased complexity | AWS CodeDeploy, Lambda, API Gateway |
Ultimately, the choice between Blue/Green, Canary, and Rolling deployment strategies mainly depend on aspects such as team capacity, tolerance for risk, application requirements, and end-user expectations. Being familiar with these deployment strategies and how to effectively implement them in a cloud environment like AWS certainly adds invaluable skills for any SysOps Administrator and is a significant aspect of the SOA-C02 exam preparation.
Practice Test
True or False: Blue/Green deployment model allows you to reduce downtime during deployments.
- True
- False
Answer: True
Explanation: Blue/Green deployment model reduces risks by running two identical production environments known as Blue and Green, allowing a safe way to migrate users’ traffic to the new version without downtime.
True or False: Canary deployment is not an appropriate strategy for testing a new feature on a small percentage of users before giving it to everyone.
- True
- False
Answer: False
Explanation: Canary deployment is specifically for gradually rolling out changes to a subset of users, making it a perfect strategy for testing new features.
What is the main advantage of Rolling deployment?
- A. No Downtime
- B. All users get the new version at once
- C. No extra resources are needed
- D. All of the above
Answer: C. No extra resources are needed
Explanation: Rolling deployment divides the instances into subsets and deploys the new version to one subset at a time, making it not require extra resources. It however may result in downtime and users getting the new version gradually.
Multiple Select: Which of the following are types of monolithic deployment scenarios?
- A. Blue/Green
- B. Canary
- C. Rolling
- D. Spiral
Answer: A. Blue/Green, B. Canary, C. Rolling
Explanation: Blue/Green, Canary, and Rolling are popular monolithic deployment scenarios. Spiral is not a monolithic deployment scenario.
Single Select: For a zero-downtime deployment, which strategy is more appropriate?
- A. Blue/Green
- B. Rolling
- C. Canary
Answer: A. Blue/Green
Explanation: Blue/Green deployment model swaps environments with no downtime, making it suitable for zero-downtime deployment.
True or False: A Canary deployment model requires additional resources.
- True
- False
Answer: True
Explanation: A Canary deployment deploys the new version on a subset of instances, requires additional resources for maintaining two versions of the application in parallel.
Single Select: What AWS service can be used to deploy your application to several AWS services?
- A. AWS Elastic Beanstalk
- B. AWS Lambda
- C. Amazon Redshift
- D. AWS Green/Blue
Answer: A. AWS Elastic Beanstalk
Explanation: AWS Elastic Beanstalk is a service that allows you to deploy and run applications without worrying about the underlying infrastructure.
True or False: Blue/Green deployment model is used for critical production environments.
- True
- False
Answer: True
Explanation: Blue/Green deployment is ideal for critical production environments to ensure zero downtime during software deployment, and immediate rollback in case issues are detected.
Single Select: Which deployment scenario is associated with gradually shifting user traffic from one version to another?
- A. Blue/Green
- B. Rolling
- C. Canary
Answer: C. Canary
Explanation: Canary deployment gradually redirects a small percentage of users to a new version until it is proven safe and all traffic is redirected.
Single Select: Which AWS service helps to automate deployments to Amazon EC2 instances?
- A. AWS Elastic Beanstalk
- B. Amazon ECS
- C. AWS CodeDeploy
- D. Amazon S3
Answer: C. AWS CodeDeploy
Explanation: AWS CodeDeploy automates code deployments to any instance, including Amazon EC2 instances and instances running on-premises.
True or False: AWS Elastic Beanstalk does not support Blue/Green deployment.
- True
- False
Answer: False
Explanation: AWS Elastic Beanstalk does support Blue/Green deployments, providing the ability to clone existing environments and swap URLs between them.
Single Select: Which one among these is NOT a deployment strategy?
- A. Blue/Green
- B. Rolling
- C. Canary
- D. Amazon S3
Answer: D. Amazon S3
Explanation: Amazon S3 is a storage service, not a deployment strategy.
True or False: Rolling deployments don’t have any impact on the application availability.
- True
- False
Answer: False
Explanation: During a rolling deployment, new versions are gradually rolled out. This means that some users may not have access to the newest features until the deployment is completed.
Single Select: What deployment strategy involves two identical environments with only one serving live user traffic at any given time?
- A. Rolling
- B. Canary
- C. Blue/Green
- D. None of the above
Answer: C. Blue/Green
Explanation: In a Blue/Green deployment, the ‘Blue’ environment is live serving user traffic while the ‘Green’ is idle. When an update is ready, the ‘Green’ environment is updated and switched to be the live environment.
Multiple Select: Which of the following are typical benefits of the Canary release strategy?
- A. Controlling the impact of negative user reaction to a new release
- B. Easier rollback
- C. Identifying and fixing bugs sooner
- D. Shortening software development cycles
Answer: A. Controlling the impact of negative user reaction to a new release, B. Easier rollback, C. Identifying and fixing bugs sooner
Explanation: Canary release strategy allows for a controlled rollout to a small subset of users and is particularly useful to limit the exposure to any bugs or issues, making it easier to rollback and fix the issues.
Interview Questions
What is the main purpose of blue-green deployment in AWS?
Blue-green deployment is a strategy that aims to reduce downtime and risk by running two identical production environments known as Blue and Green. At any time, only one of the environments is live and the other is ready to take over at any moment in case anything goes wrong.
What is rolling deployment in AWS?
Rolling deployment is a strategy where the new version of the application gradually replaces the old version. This is done by replacing instances of the old version of the application with the new version gradually.
Explain the role of AWS Elastic Beanstalk as a managed service in deployment scenarios?
AWS Elastic Beanstalk is a PaaS (Platform as a Service) offered by Amazon Web Services. Users can easily deploy and run applications in multiple languages without worrying about infrastructure management. Elastic Beanstalk handles capacity provisioning, load balancing, and automatic scaling.
What is a Canary Release in AWS and why is it used?
Canary releasing is a technique to reduce the risk of introducing a new software version in production by rolling out the change to a small subset of users before it is rolled out to the entire infrastructure. It is used to ensure that the software runs as expected without impacting the entire user base.
In accordance with the AWS Well-Architected Framework, how can you improve your deployment strategy?
The strategy can be improved through automation, where it would minimize human error, facilitate consistent responses, and enable frequent and predictable deployment.
What are the benefits of employing a blue/green deployment with AWS?
The benefits include zero downtime during deployments, instant rollback, and simpler process as it separates the live production environment from the testing or staging environment.
How does AWS CodeDeploy facilitate blue/green deployments?
AWS CodeDeploy facilitates blue/green deployments by routing production traffic from an old version to a new version. It automatically scales down the old versions, reducing the extra costs involved in running two environments simultaneously.
What is the purpose behind using the AWS Lambda service in deployment scenarios?
AWS Lambda is a serverless computing service that automatically manages the compute resources for applications. Developers can simply write code and upload it to Lambda, without the need to manage servers, making it an excellent choice for deploying applications swiftly.
How do health checks get used in a blue/green deployment strategy?
Health checks are used to ensure that the new service is capable of handling production traffic before switching from the blue environment. If the health check fails, the traffic can be immediately rerouted to the blue environment, minimizing the impact on users.
In a rolling deployment on AWS, how can you ensure zero downtime?
On AWS, you can use the Elastic Load Balancer to balance the traffic between versions. When a new batch of instances is ready, the load balancer begins to send a small portion of traffic to the new version. If everything goes well, more and more traffic is routed to the new version. This ensures zero downtime.
How are similar and different the blue/green and canary deployments?
Both blue/green and canary deployments aim for zero-downtime and testing in the production environment. However, they implement the procedure differently. In blue/green deployments, all requests are moved immediately to the new version once it’s tested. In contrast, a canary release moves a small amount of traffic initially before fully transitioning.
How can AWS Auto Scaling be used in deployment scenarios?
AWS Auto Scaling can be used to automatically adjust resources to maintain application performance at the lowest cost. During deployment, new instances can be added to share the load of incoming traffic which results in better performance and user experience.
What are the benefits of using AWS Elastic Beanstalk for deployment?
AWS Elastic Beanstalk automates the details of capacity provisioning, load balancing, scaling, and application health monitoring. It simplifies deployment and allows developers to focus more on writing code rather than managing infrastructural details.
What is a microservices deployment strategy on AWS?
Microservices deployment strategy involves developing an application as a suite of small services, each running in its own process and communicating with lightweight mechanisms. AWS offers various services like AWS Lambda, Amazon API Gateway, and Amazon ECS to support microservices architectural style.
How does AWS CodeDeploy handle failed deployments?
If a deployment fails, AWS CodeDeploy automatically attempts to roll back the deployment to the previous, last known good version. It ensures that application availability is not affected due to a failed deployment.
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