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Difficulty: HardDeployment Strategies

A developer is configuring an in-place deployment in AWS CodeDeploy for an application running on an Auto Scaling group with 1010 Amazon EC2 instances. To prevent performance degradation during peak hours, the application must maintain at least 60%60\% of its capacity (66 instances) to serve traffic at all times during the deployment. The developer also wants to complete the deployment in the shortest time possible. Which deployment configuration should the developer use to meet these requirements?

  1. Create a custom deployment configuration with the minimum healthy hosts set to a fleet percentage of 60%60\%.Answer
  2. B
    Use the predefined CodeDeployDefault.HalfAtATime deployment configuration.
  3. C
    Use the predefined CodeDeployDefault.OneAtATime deployment configuration.
  4. D
    Create a custom deployment configuration with the minimum healthy hosts set to a host count of 44.

Answer

Create a custom deployment configuration with the minimum healthy hosts set to a fleet percentage of 60%60\%.
The correct option is the custom deployment configuration with the minimum healthy hosts set to a fleet percentage of 60%60\%. This ensures that at least 66 instances (which is 60%60\% of 1010 instances) remain healthy and serving traffic throughout the deployment. Consequently, CodeDeploy can update up to 44 instances concurrently, minimizing the total deployment duration while satisfying the capacity constraint.

Step-by-Step Solution

1
Calculate the number of healthy instances required during the deployment.
The application requires at least 60%60\% of 1010 instances to be healthy, which equals 10×0.60=610 \times 0.60 = 6 healthy instances.
This establishes the minimum capacity baseline that must be maintained.
2
Determine the maximum number of instances that can be updated concurrently.
Maximum updating instances = Total instances - Minimum healthy instances = 10−6=410 - 6 = 4 instances.
To complete the deployment in the shortest time, we must update the maximum allowable number of instances concurrently.
3
Evaluate the predefined CodeDeploy configurations against the constraints.
HalfAtATime updates 55 instances (leaving 55 healthy, violating the limit). OneAtATime updates 11 instance (taking too long). AllAtOnce updates all 1010 (violating the limit).
Predefined configurations do not optimize for updating exactly 44 instances at a time while keeping 66 healthy.
4
Define the custom configuration parameters.
A custom configuration with minimum healthy hosts set to a fleet percentage of 60%60\% (or a host count of 66) is required.
Setting the minimum healthy hosts to a fleet percentage of 60%60\% ensures exactly 66 instances remain healthy, permitting 44 instances to update concurrently, thus meeting both capacity and speed constraints.

Key Concept

AWS CodeDeploy deployment configurations and minimum healthy hosts parameters.
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Topics

Deployment Strategies

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