In Kubernetes, understanding exit codes is essential for diagnosing and resolving issues that arise within containers. Exit codes are returned by processes to indicate their success or failure. Each exit code has a specific meaning that helps developers troubleshoot problems efficiently.
Exit codes are numerical values returned by a process when it terminates. They indicate whether the process executed successfully or encountered an error. A zero exit code typically means success, while any non-zero exit code indicates a failure, with specific codes signifying different types of errors.
Exit codes are generated by the underlying operating system and are often the result of various factors, such as:
- Command syntax errors
- Resource limitations (e.g., memory or CPU)
- Signal termination
- Application-specific errors
By understanding the exit codes, you can identify the root cause of issues and take corrective action.
Below is a list of common exit codes, their meanings, and links to hands-on examples available in this repository:
| Exit Code | Meaning | Reference |
|---|---|---|
| 0 | Success | Exit Code 0 |
| 1 | Generic error | Exit Code 1 |
| 2 | Misuse of shell builtins | Exit Code 2 |
| 125 | Command invoked cannot execute | Exit Code 125 |
| 126 | Command invoked cannot execute (permission) | Exit Code 126 |
| 127 | Command not found | Exit Code 127 |
| 128 | Invalid exit argument | Exit Code 128 |
| 130 | Script terminated by Control-C | Exit Code 130 |
| 134 | Abnormal termination (SIGABRT) | Exit Code 134 |
| 137 | Container killed by OOM (Out of Memory) | Exit Code 137 |
| 139 | Segmentation fault (SIGSEGV) | Exit Code 139 |
| 141 | Broken pipe (SIGPIPE) | Exit Code 141 |
| 143 | Graceful termination (SIGTERM) | Exit Code 143 |
| 255 | Exit status out of range | Exit Code 255 |
For detailed hands-on examples and simulations for each exit code, please refer to the individual README files linked above. Each of these files provides:
- An explanation of the exit code
- Sample Kubernetes manifests for simulating the exit code
- Suggested fixes for resolving issues associated with the exit code
- Prevention strategies for avoiding similar issues in the future
By utilizing these resources, you can enhance your understanding of Kubernetes troubleshooting and improve your ability to manage containerized applications effectively.