Can't start yarn after cleaning /tmp

[#1]

Searching on internet I found that I can clean the tmp directory without problem on a cloudera cluster, so I did it.

Now, when I try to start the cluster all services goes up well, but yarn failed to start with this error:

19/10/16 15:50:17 FATAL nodemanager.NodeManager: Error starting NodeManager
org.apache.hadoop.yarn.exceptions.YarnRuntimeException: NMWebapps failed to start.
        at org.apache.hadoop.yarn.server.nodemanager.webapp.WebServer.serviceStart(WebServer.java:79)
        at org.apache.hadoop.service.AbstractService.start(AbstractService.java:193)
        at org.apache.hadoop.service.CompositeService.serviceStart(CompositeService.java:120)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.serviceStart(NodeManager.java:329)
        at org.apache.hadoop.service.AbstractService.start(AbstractService.java:193)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.initAndStartNodeManager(NodeManager.java:563)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.main(NodeManager.java:609)
Caused by: org.apache.hadoop.yarn.webapp.WebAppException: Error starting http server
        at org.apache.hadoop.yarn.webapp.WebApps$Builder.start(WebApps.java:279)
        at org.apache.hadoop.yarn.server.nodemanager.webapp.WebServer.serviceStart(WebServer.java:65)
        ... 6 more
Caused by: java.io.IOException: Unable to initialize WebAppContext
        at org.apache.hadoop.http.HttpServer2.start(HttpServer2.java:922)
        at org.apache.hadoop.yarn.webapp.WebApps$Builder.start(WebApps.java:274)
        ... 7 more
Caused by: java.io.FileNotFoundException: /tmp/Jetty_0_0_0_0_8042_node____19tj0x/webapp/webapps/node/.keep (No such file or directory)
        at java.io.FileOutputStream.open0(Native Method)
        at java.io.FileOutputStream.open(FileOutputStream.java:270)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:162)
        at org.mortbay.resource.JarResource.extract(JarResource.java:215)
        at org.mortbay.jetty.webapp.WebAppContext.resolveWebApp(WebAppContext.java:974)
        at org.mortbay.jetty.webapp.WebAppContext.getWebInf(WebAppContext.java:832)
        at org.mortbay.jetty.webapp.WebInfConfiguration.configureClassLoader(WebInfConfiguration.java:62)
        at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:489)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152)
        at org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:156)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
        at org.mortbay.jetty.Server.doStart(Server.java:224)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.apache.hadoop.http.HttpServer2.start(HttpServer2.java:900)

What can I do?

[#2]

@Cico 

Error indicates that the yarn user is unable to access the file  /tmp/Jetty_0_0_0_0_8042_node____19tj0x/webapp/webapps/node/.keep 

It seems there is an issue with /tmp directory permissions on local.

Login to the particular Nodemanager node which reports the error and check if /tmp directory permissions are set to 777. This should allow yarn user to access the file

# chmod 777 /tmp

[#3]

There is no file Jetty_0_0_0_0_8042_node in /tmp, the partition is been wiped out.

Is not a problem of permission, but of missing file.

How can I let yarn to remake those files? 

[#4 · Accepted solution]

@Cico 

If the permissions are already set to 777 for /tmp , restart the particular node manager from Cloudera Manager. This should allow the creation of new file in /tmp. 

[#5]

Thank you very much!

You saved the day.