SOA-C02 Deployment, Provisioning, and Automation Practice Question
A company uses AWS CodeDeploy to automate deployments to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed deployment'. The logs on a failed instance show that the 'BeforeInstall' lifecycle event script exited with a non-zero exit code. What is the MOST likely cause?
⚠ Common exam trap
Many candidates confuse the cause of a deployment failure with external factors like permissions or health checks, but the logs explicitly point to the BeforeInstall script's non-zero exit code, making a script bug the direct and most likely cause.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The BeforeInstall script has a bug that causes it to exit with a non-zero exit code.
The error message indicates that the deployment failed because too many instances failed, and the logs on a failed instance show that the 'BeforeInstall' lifecycle event script exited with a non-zero exit code. In AWS CodeDeploy, each lifecycle event script must exit with a zero exit code to indicate success; any non-zero exit code is treated as a failure, causing the deployment to fail on that instance. Since the logs explicitly point to the BeforeInstall script's non-zero exit, the most likely cause is a bug in that script.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The BeforeInstall script has a bug that causes it to exit with a non-zero exit code.
Why this is correct
The BeforeInstall hook is a lifecycle event in a CodeDeploy deployment. If the script exits with any non-zero exit code, CodeDeploy treats that as an unrecoverable failure and immediately stops the deployment, marking the instance as failed. A bug such as a missing command, a syntax error, or a failed dependency check would produce exactly this behavior, and the agent log would show the script's error output.
- ✗
The instance does not have the required permissions to download the application revision.
Why it's wrong here
A lack of required permissions for the instance to download the application revision would cause the CodeDeploy agent to fail during the DownloadBundle step, which runs before any lifecycle hook executes. Because that failure occurs prior to BeforeInstall, you would see a 'download failed' error or an access denied message rather than a failure inside the BeforeInstall script. Therefore, permission issues cannot explain a failure that occurs during BeforeInstall.
- ✗
The instance is not healthy according to the Elastic Load Balancer health checks.
Why it's wrong here
Elastic Load Balancer health checks are evaluated during the ValidateService and LoadBalancer registration phases, after the application has been installed and started. They are not invoked before or during the BeforeInstall hook, so an unhealthy instance would not cause the script to exit with a non-zero code. A health check failure would instead surface later as a deployment timeout or an instance that does not pass validation, not as a script error in BeforeInstall.
- ✗
The CodeDeploy agent is not running on the instance.
Why it's wrong here
The CodeDeploy agent is the process that downloads the revision, runs lifecycle hooks, and reports the deployment status to the AWS service. If the agent were not running, the deployment would remain stuck or fail with an AgentNotAvailable error, and no lifecycle script would execute. The fact that the BeforeInstall script ran and produced output proves the agent is alive and actively executing, so an agent stoppage is ruled out.
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1 more way this is tested on SOA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses AWS CodeDeploy to deploy applications to an Auto Scaling group. The deployment fails with the error: 'The overall deployment failed because too many individual instances failed deployment, too few healthy instances are available for deployment, or some instances in your deployment group are experiencing problems.' The SysOps administrator checks the deployment logs and finds that the application installation script exits with a non-zero exit code. What is the MOST likely cause?
medium- A.The Auto Scaling group does not have enough instances to meet the minimum capacity.
- B.The security group for the instances blocks outbound traffic to CodeDeploy endpoints.
- ✓ C.The AppSpec file contains a lifecycle hook that fails.
- D.The CodeDeploy agent is outdated on the instances.
Why C: A non-zero exit code from an AppSpec lifecycle hook (e.g., ApplicationStop, BeforeInstall, AfterInstall, ApplicationStart, ValidateService) during the deployment process causes the overall deployment to fail. The error message indicates that individual instances failed deployment, and the installation script exiting with a non-zero exit code is a direct sign of a lifecycle hook failure. Option A is incorrect because insufficient instances in the Auto Scaling group would trigger a different error related to minimum capacity, not a script exit code. Option B is incorrect because the security group blocking outbound traffic would prevent the CodeDeploy agent from communicating with the service, resulting in a connection error, not a script exit code issue. Option D is incorrect because an outdated CodeDeploy agent would typically produce agent-specific errors or version mismatch warnings, not a non-zero exit code from the installation script.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.