[jira] [Commented] (NIFI-2199) NiFi cannot be restarted through SSH (nifi.sh hangs)

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-2199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15544999#comment-15544999 ] 

ASF GitHub Bot commented on NIFI-2199:
--------------------------------------

GitHub user michalklempa opened a pull request:

    https://github.com/apache/nifi/pull/1092

    Fixes NIFI-2199 nifi.sh hangs on restart through ssh

    When nifi.sh is executed remotely through ssh:
    ```
    ssh root@example.com /etc/init.d/nifi restart
    ```
    SSH session hang forever, due to unclosed STDIN/OUT/ERR streams in nifi process. Redirecting these streams from and to `/dev/null` fixes the problem.


You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/michalklempa/nifi NIFI-2199_nifi_sh_hangs

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/nifi/pull/1092.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 #1092
    
----
commit 6488bdec2a429b735a02949694ff8876ae91d22e
Author: Michal Klempa <mi...@gmail.com>
Date:   2016-10-04T10:18:46Z

    Fixes NIFI-2199 nifi.sh hangs on restart through ssh

----


> NiFi cannot be restarted through SSH (nifi.sh hangs)
> ----------------------------------------------------
>
>                 Key: NIFI-2199
>                 URL: https://issues.apache.org/jira/browse/NIFI-2199
>             Project: Apache NiFi
>          Issue Type: Bug
>    Affects Versions: 0.5.1, 0.6.1
>            Reporter: Michal Klempa
>            Priority: Minor
>              Labels: initscript
>
> When NiFi is to restarted using SSH from remote host, nifi.sh causes SSH to hang on open io streams.
> Steps to reproduce:
> 1. HostA - NiFi instalation
> 2. HostB - client machine
> 3. log to HostB
> 4. issue a command
> {code}
> ssh root@HostA /etc/init.d/nifi restart
> {code}
> Expected behavior: NiFi is restarted, SSH command exits with 0
> Actual behavior: NiFi is restarted, SSH command hang on
> This seems to be somehow related to SSH handling IO streams of process. Seems like detached NiFi java process does not close stdin/out/err (i do not know precisely) leading to sshd waiting for some input/output to come to client.
> I was able to do a quick&dirty fix in nifi.sh as follows:
> 1. on existing nifi installation, in file /etc/init.d/nifi find the line
> {code}
> (cd "${NIFI_HOME}" && ${sudo_cmd_prefix} "${JAVA}" -cp "${BOOTSTRAP_CLASSPATH}" -Xms12m -Xmx24m -Dorg.apache.nifi.bootstrap.config.file="${BOOTSTRAP_CONF}" org.apache.nifi.bootstrap.RunNiFi $@ &)
> {code}
> its line number 214 (true branch of if [ "$1"] = "start"] condition).
> 2. replace it by line:
> {code}
> (cd "${NIFI_HOME}" && ${sudo_cmd_prefix} "${JAVA}" -cp "${BOOTSTRAP_CLASSPATH}" -Xms12m -Xmx24m -Dorg.apache.nifi.bootstrap.config.file="${BOOTSTRAP_CONF}" org.apache.nifi.bootstrap.RunNiFi $@ > /dev/null 2>&1 < /dev/null &)
> {code}
> This simply redirects stdin from /dev/null to NiFi java process and redirects stdout/err to /dev/null letting SSH to close the session.
> After applying this fix, I am able to restart NiFi remotely using SSH.
> Use case for this scenario: When Flow Manager develop flow.xml.gz on localhost/testing environments, usually deployment to production environment is handled by jenkins/bamboo CI tools. These tools need to log in, upload new flow.xml.gz and restart NiFi. All remotely using SSH.
> If somebody can advice me where in the source code is this line of code located, I can prepare a pull request for this quick&dirty fix.
> But. Maybe we may want to go further and investigate what to do with IO streams inside Java...



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