GitHub user GabrielBrascher opened a pull request:
https://github.com/apache/cloudstack/pull/1459
Cloudstack 8611 Handle SSH if server "forget" to send exit status
<h5> Continuing the work started by @likitha, I cherry-picked the
commit (b9181c689e0e7b5f1e28c81d73710196dfabd0ba) from PR
<https://github.com/apache/cloudstack/pull/561>. </h5>
I made some changes from the cherry-picked commit adding @wilderrodrigues
suggestions (create simple methods that could be reused and make unit tests
feasible).
Also, tried to simplify the logic by assuming that ....
if ((conditions & ChannelCondition.EXIT_STATUS) != 0) {
if ((conditions & (ChannelCondition.STDOUT_DATA |
ChannelCondition.STDERR_DATA)) == 0) {
break;
}
}
... is the same as `((conditions & ChannelCondition.EXIT_STATUS) != 0) &&
((conditions & (ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA))
== 0)`. This expression has the following results according to each possible
condition.
|Condition|Value|result
|-----------------|-------|------|
TIMEOUT | 0000001|false
CLOSED | 0000010 |false
STDERR_DATA | 0000100 | false
STDERR_DATA | 0001000 | false
EOF | 0010000 | false
EXIT_STATUS | 0100000 | **true**
EXIT_SIGNAL | 1000000 | false
Testing all the possibilities, it is possible to note that the condition of
(newConditions & ChannelCondition.EXIT_STATUS) != 0)`` is sufficient; thus the
simplified "if" conditional can be:
`if ((conditions & ChannelCondition.EXIT_STATUS) != 0) {
break;
}`
This proposed work can be explained by quoting @likitha:
>CheckS2SVpnConnectionsCommand execution involves executing a script
(checkbatchs2svpn.sh) in the virtual router. Once CS has opened a session to a
virtual router and executed a script in the router, it waits indefinitely till
the session either times out or the exit status of the remote process is
available. But it is possible that an EOF is reached by the process in the
router and the router never set the exit status.
>References -
>1. Some servers never send the exit status, or occasionally "forget" to do
so
(http://grepcode.com/file/repo1.maven.org/maven2/org.jvnet.hudson/trilead-ssh2/build212-hudson-1/com/trilead/ssh2/ChannelCondition.java).
>2. Get the exit code/status from the remote command - if available. Be
careful - not all server implementations return this value -
(http://grepcode.com/file/repo1.maven.org/maven2/org.jvnet.hudson/trilead-ssh2/build212-hudson-1/com/trilead/ssh2/Session.java#Session.waitForCondition%28int%2Clong%29).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/GabrielBrascher/cloudstack CLOUDSTACK-8611
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/cloudstack/pull/1459.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1459
----
commit 1409f981f298bfe60a1791222ca0e62276659cad
Author: Likitha Shetty <[email protected]>
Date: 2015-05-01T11:14:51Z
CLOUDSTACK-8611. CS waits indefinitely for CheckS2SVpnConnectionsCommand to
return.
While remote executing commands through ssh, handle channel condition of
EOF because we wait for the the condition.
commit 96d76d41ab38ab5459e3b3c685633fb8f41cf609
Author: gabrascher <[email protected]>
Date: 2016-04-01T06:21:16Z
Handle SSH if server "forget" to send exit status.
Cherry-picked the work started by https://github.com/likitha
commit (b9181c689e0e7b5f1e28c81d73710196dfabd0ba) from PR
https://github.com/apache/cloudstack/pull/561.
CS waits indefinitely for CheckS2SVpnConnectionsComm and to return.
While remote executing commands through ssh, handle channel condition of
EOF because we wait for the the condition.
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