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DocumentationTencent Kubernetes EngineFault HandlingPod Status Exception and HandlingPod exception troubleshooterUse Exit Code to Identify Pod Exceptions
Use Exit Code to Identify Pod Exceptions
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Last updated: 2025-01-23 17:59:44
Use Exit Code to Identify Pod Exceptions
Last updated: 2025-01-23 17:59:44
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This document describes how to use exit codes to troubleshoot pod issues.

Querying Pod Exceptions

Run the following command to query pod exceptions:
kubectl describe pod <pod name>
The returned result is as follows:
Containers:
  kubedns:
    Container ID:  docker://5fb8adf9ee62afc6d3f6f3d9590041818750b392dff015d7091eaaf99cf1c945
    Image:         ccr.ccs.tencentyun.com/library/kubedns-amd64:1.14.4
    Image ID:      docker-pullable://ccr.ccs.tencentyun.com/library/kubedns-amd64@sha256:40790881bbe9ef4ae4ff7fe8b892498eecb7fe6dcc22661402f271e03f7de344
    Ports:         10053/UDP, 10053/TCP, 10055/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      --domain=cluster.local.
      --dns-port=10053
      --config-dir=/kube-dns-config
      --v=2
    State:          Running
      Started:      Tue, 27 Aug 2019 10:58:49 +0800
    Last State:     Terminated
      Reason:       Error
      Exit Code:    255
      Started:      Tue, 27 Aug 2019 10:40:42 +0800
      Finished:     Tue, 27 Aug 2019 10:58:27 +0800
    Ready:          True
    Restart Count:  1
Exit Code is the status code of the last container exit. If it is not 0, the container exited due to an exception. You can use the exit code to further troubleshoot the problem.

Exit Codes

A valid exit code is between 0 and 255.
0 means the container exited normally.
If the container exited due to an external signal, the exit code is between 129 and 255. For example, if the operating system sent kill -9 or ctrl+c as the termination signal, the status is SIGKILL or SIGINT.
If the container exited due to an internal signal, the exit code is between 1 and 128. However, in some circumstances, the exit code might be between 129 and 255.
If the specified exit code has a value outside the 0-255 range, such as exit(-1), it is automatically translated to a value in the 0-255 range. If the exit code is specified as code, it is translated as follows:
If the exit code is negative:
256 - (|code| % 256)
If the exit code is positive:
code % 256

Typical Exit Codes

137: indicates that the process was killed by SIGKILL. Possible reasons are:
Pod memory reached resources.limits, such as Out of Memory (OOM). Pod resource limits are implemented by using Linux cgroup. If the memory of a pod reaches its limit, cgroup forces it to stop (with a similar effect to kill -9). If you use describe pod, you can see the value of Reason is OOMKilled.
If the host does not have sufficient resources (OOM), the kernel stops some processes to free up the memory.
Note:
If the process is stopped due to OOM, cgroup, or the host, you can find relevant records in system logs:
Ubuntu system logs are stored in /var/log/syslog, whereas CentOS system logs are stored in /var/log/messages. You can run the journalctl -k command to view system logs in both operating systems.
livenessProbe failed, which causes kubelet to stop the pod.
Pod stopped by a trojan process.
1 and 255: indicates common issues. Check container logs for further troubleshooting. For example, this could be the result of exit(1) or exit(-1). -1 is translated to 255.

Standard Linux Interruption Signals

Linux programs send an exit code when they are interrupted by external signals. The value of the exit code is the value of the interrupt signal plus 128. For example, the value of SIGKILL is 9, so the program exit code is 9 + 128 = 137. For more standard interrupt signals, see the following table:
Signal
Status Code Value
Action
Description
SIGHUP
1
Term
Hangup detected on controlling terminal or death of controlling process
SIGINT
2
Term
Interrupt from keyboard
SIGQUIT
3
Core
Quit from keyboard
SIGILL
4
Core
Illegal Instruction
SIGABRT
6
Core
Abort signal from abort(3)
SIGFPE
8
Core
Floating-point exception
SIGKILL
9
Term
Kill signal
SIGSEGV
11
Core
Invalid memory reference
SIGPIPE
13
Term
Broken pipe: write to pipe with no readers; see pipe(7)
SIGALRM
14
Term
Timer signal from alarm(2)
SIGTERM
15
Term
Termination signal
SIGUSR1
30,10,16
Term
User-defined signal 1
SIGUSR2
31,12,17
Term
User-defined signal 2
SIGCHLD
20,17,18
Ign
Child stopped or terminated
SIGCONT
19,18,25
Cont
Continue if stopped
SIGSTOP
17,19,23
Stop
Stop process
SIGTSTP
18,20,24
Stop
Stop typed at terminal
SIGTTIN
21,21,26
Stop
Terminal input for background process
SIGTTOU
22,22,27
Stop
Terminal output for background process


C/C++ Exit Codes

/usr/include/sysexits.h provides standardized exit codes for C and C++. These codes are described in the following table:
Definition
Status Code
Description
#define EX_OK
0
successful termination
#define EX__BASE
64
base value for error messages
#define EX_USAGE
64
command line usage error
#define EX_DATAERR
65
data format error
#define EX_NOINPUT
66
cannot open input
#define EX_NOUSER
67
addressee unknown
#define EX_NOHOST
68
host name unknown
#define EX_UNAVAILABLE
69
service unavailable
#define EX_SOFTWARE
70
internal software error
#define EX_OSERR
71
system error (e.g., can't fork)
#define EX_OSFILE
72
critical OS file missing
#define EX_CANTCREAT
73
can't create (user) output file
#define EX_IOERR
74
input/output error
#define EX_TEMPFAIL
75
temp failure; user is invited to retry
#define EX_PROTOCOL
76
remote error in protocol
#define EX_NOPERM
77
permission denied
#define EX_CONFIG
78
configuration error
#define EX__MAX 78
78
maximum listed value


Status Code Reference

For the description of more status codes, see the following table:
Status Code
Meaning
Example
Description
1
Catchall for general errors
let "var1 = 1/0"
Miscellaneous errors, such as "divide by zero" and other impermissible operations
2
Misuse of shell builtins (according to Bash documentation)
empty_function() {}
Missing keyword or command, or permission problem (and diff return code on a failed binary file comparison).
126
Command invoked cannot execute
/dev/null
Permission problem or command is not an executable
127
"command not found"
illegal_command
Possible problem with $PATH or a typo
128
Invalid argument to exit
exit 3.14159
exit takes only integer args in the range 0 - 255 (see first footnote)
128+n
Fatal error signal "n"
kill -9 $PPID of script
$? returns 137 (128 + 9)
130
Script terminated by Control-C
Ctl-C
Control-C is fatal error signal 2, (130 = 128 + 2, see above)
255*
Exit status out of range
exit -1
exit takes only integer args in the range 0 - 255

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