Details
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Bug
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Status: Open
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Blocker
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Resolution: Unresolved
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1.9.0
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None
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Patch, Important
Description
Phenomenon
In many cases, we have just read permission on spoolDir and write permission on trackerDir.
However whenever flume starts for spooldir source , it will always try to create a '.canary' file in the spooling directory.
Then it leads to the failure of some processing unnecessarily.
Recur
(Usually spooldir is mounted readonly from a nas in production and this time we create a readonly directory instead.)
First we create the spoolDir by root user and create a file in it and it is readonly for others by default.
su root
mkdir /home/hadoop/testspooldir
echo 'foo' > /home/hadoop/testspooldir/bar
Then switch to another user (hadoop) who runs flume and make sure it has read permission for the spooldir.
su hadoop mkdir /home/hadoop/testtrackerdir ll /home/hadoop/testspooldir >> total 4-rw-r--r-- 1 root root 4 Jan 16 19:15 bar
now create the example.conf:
a1.sources = r1 a1.sinks = k1 a1.channels = c1 a1.sources.r1.type = spooldir a1.sources.r1.deletePolicy = never a1.sources.r1.spoolDir = /home/hadoop/testspooldir a1.sources.r1.trackerDir = /home/hadoop/testtrackerdir a1.sources.r1.trackingPolicy = tracker_dir a1.sinks.k1.type = logger a1.channels.c1.type = memory a1.channels.c1.capacity = 1000 a1.channels.c1.transactionCapacity = 100 a1.sources.r1.channels = c1 a1.sinks.k1.channel = c1
and start flume with it
bin/flume-ng agent --conf conf --conf-file conf/example.conf --name a1 -Dflume.root.logger=INFO,console
then the IOException is thrown.
2020-01-16 19:16:12,777 (lifecycleSupervisor-1-0) [ERROR - org.apache.flume.lifecycle.LifecycleSupervisor$MonitorRunnable.run(LifecycleSupervisor.java:251)] Unabl2020-01-16 19:16:12,777 (lifecycleSupervisor-1-0) [ERROR - org.apache.flume.lifecycle.LifecycleSupervisor$MonitorRunnable.run(LifecycleSupervisor.java:251)] Unable to start EventDrivenSourceRunner: { source:Spool Directory source r1: { spoolDir: /home/hadoop/testspooldir } } - Exception follows.org.apache.flume.FlumeException: Unable to read and modify files in the spooling directory: /home/hadoop/testspooldir at org.apache.flume.client.avro.ReliableSpoolingFileEventReader.<init>(ReliableSpoolingFileEventReader.java:195) at org.apache.flume.client.avro.ReliableSpoolingFileEventReader.<init>(ReliableSpoolingFileEventReader.java:89) at org.apache.flume.client.avro.ReliableSpoolingFileEventReader$Builder.build(ReliableSpoolingFileEventReader.java:882) at org.apache.flume.source.SpoolDirectorySource.start(SpoolDirectorySource.java:111) at org.apache.flume.source.EventDrivenSourceRunner.start(EventDrivenSourceRunner.java:44) at org.apache.flume.lifecycle.LifecycleSupervisor$MonitorRunnable.run(LifecycleSupervisor.java:249) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)Caused by: java.io.IOException: Permission denied at java.io.UnixFileSystem.createFileExclusively(Native Method) at java.io.File.createTempFile(File.java:2024) at org.apache.flume.client.avro.ReliableSpoolingFileEventReader.<init>(ReliableSpoolingFileEventReader.java:185) ... 12 more
Fix
We just add the condition where this trick is necessary.
The pr/patch will be submitted as as shown below.
Or let it still exist and using warning log instead of exception thrown is better?
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