A developer is using AWS CodeDeploy to deploy an application to a fleet of Amazon EC2 instances. During a recent deployment, some instances failed with a 'ScriptTimedOut' error during the 'AfterInstall' hook, even though the script typically completes within 30 seconds. The CodeDeploy agent logs on the affected instances show that the script started successfully but then no further output was recorded until the timeout. The default timeout for CodeDeploy hooks is 3600 seconds (1 hour). What is the MOST likely cause of this 'ScriptTimedOut' error?
- AThe EC2 instance's security group is blocking outbound network access required by the script during 'AfterInstall'.
- BThe IAM instance profile attached to the EC2 instances lacks permissions for the CodeDeploy agent to write logs to CloudWatch Logs.
- CThe CodeDeploy agent process on the EC2 instance crashed or was stopped prematurely.
- DThe 'timeout' setting for the specific 'AfterInstall' hook in the AppSpec file is set to a value lower than the script's execution time.
Show answer & explanationAnswer & explanation
Correct answer: D. The 'timeout' setting for the specific 'AfterInstall' hook in the AppSpec file is set to a value lower than the script's execution time.
CodeDeploy hook timeouts can be explicitly set in the AppSpec file. While the *default* timeout for CodeDeploy hooks is 3600 seconds, a developer can override this for individual hooks. If the 'AfterInstall' hook's timeout was explicitly set to a value (e.g., 60 seconds) that is lower than the script's actual execution time (even if it's usually 30 seconds, a spike to 61+ seconds would cause a timeout), this would explain the 'ScriptTimedOut' error.
Why the other options are wrong
- A. Network access issues would typically manifest as specific connection errors within the script's output (if logs were captured) or a different type of failure, not just a silent timeout after starting, especially if the script usually completes.
- B. Lack of CloudWatch Logs permissions would prevent logs from being sent, but wouldn't directly cause the script itself to time out. The deployment would still fail, but the root cause of the script not completing would be elsewhere.
- C. If the CodeDeploy agent crashed, it would likely result in a different error, possibly about the agent being unresponsive or the deployment failing earlier, not specifically a 'ScriptTimedOut' after the script started.
CodeDeploy AppSpec Hook Timeout
AWS CodeDeploy allows developers to define a `timeout` property for individual lifecycle event hooks within the `AppSpec.yml` file. This timeout overrides the default 3600-second (1 hour) timeout for that specific hook. If the script associated with the hook takes longer than its defined `timeout`, CodeDeploy will terminate the script and report a 'ScriptTimedOut' error.
- Defined in `AppSpec.yml` under `hooks` section.
- Overrides default 3600-second timeout.
- Causes 'ScriptTimedOut' if script exceeds defined duration.
- Crucial for long-running or potentially stuck scripts.
Memory trick: CodeDeploy's 'Hooks' have a 'Secret Timer' in the AppSpec; if it runs out, the script is 'Cut'.