SOA-C02 Deployment, Provisioning, and Automation Practice Question
A company is using AWS CodeDeploy to deploy an application to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed deployment'. The SysOps administrator checks the deployment logs and finds that the BeforeInstall lifecycle event script is failing on some instances. The instances are Amazon Linux 2. What should the administrator do to troubleshoot this issue?
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
✓
Review the BeforeInstall script's output and exit code in the deployment logs or on the instance.
The error indicates that the BeforeInstall lifecycle script is failing. The correct first step is to examine the script's output and exit code, which can be found in the deployment logs (under the instance's CodeDeploy agent logs) or directly on the instance. This allows you to identify why the script is failing. Option A is not directly relevant because the issue is not agent connectivity but script execution. Option B is incorrect because changing the deployment configuration to 'OneAtATime' would only affect the pace of deployments, not fix a failing script. Option C is unnecessary because the appspec.yml syntax is likely correct if the script runs at all; the problem lies in the script itself.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Verify that the CodeDeploy agent on the instances is running and can communicate with the CodeDeploy service.
Why it's wrong here
The CodeDeploy agent is a separate component from the lifecycle hook scripts; if it were stopped or unable to reach the CodeDeploy service, the deployment would typically fail with errors such as 'agent lost' or 'connection timed out' before any script executes. Since the BeforeInstall hook is already running, the agent is active and communicating correctly. Checking agent health would not reveal why the script itself returned a non-zero exit code, so this action is not diagnostic for the reported failure.
- ✗
Ensure that the CodeDeploy deployment configuration is set to 'OneAtATime' to reduce instance failures.
Why it's wrong here
The deployment configuration 'OneAtATime' controls only the number of instances that are updated concurrently, and it does not alter the logic or execution of a lifecycle hook script. The BeforeInstall script will run with the same commands and environment regardless of whether the deployment is OneAtATime, AllAtOnce, or a percentage-based rollout. A script that fails will fail under any configuration, so changing this setting merely narrows the blast radius rather than fixing the underlying cause of the hook's failure.
- ✗
Check the appspec.yml file for syntax errors in the hooks section.
Why it's wrong here
The appspec.yml syntax is validated by CodeDeploy before any hooks are executed, so a YAML syntax error or an invalid hooks section would prevent the deployment from even reaching the BeforeInstall stage. Since the deployment has proceeded to execute the hook, the file is structurally valid. Runtime issues such as missing dependencies, permission problems, or incorrect command arguments in the script itself would not be detected by a syntax check, making this option ineffective for diagnosing the observed failure.
- ✓
Review the BeforeInstall script's output and exit code in the deployment logs or on the instance.
Why this is correct
The BeforeInstall script's exit code is the definitive indicator of hook failure: CodeDeploy expects a 0 for success, and any non-zero value tells the agent to mark the deployment as failed. The deployment logs on the instance, typically under /opt/codedeploy-agent/deployment-root/deployment-logs/, store standard output and standard error for each script, while the CodeDeploy console provides a truncated view of the last 100 lines. Reviewing these logs will reveal the actual error message and the command that failed, enabling you to correct the script or its environment.
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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.