Project: mesos
Issue MESOS-3287: downloadWithHadoop tries to access Error() for a valid Try<bool>
This was reported while trying to install Hadoop / Mesos integration: {noformat} I0818 05:36:35.058688 24428 fetcher.cpp:409] Fetcher Info: {"cache_directory":"\/tmp\/mesos\/fetch\/slaves\/20150706-075218-1611773194-5050-28439-S473\/hadoop","items":[{"action":"BYPASS_CACHE","uri":{"extract":true,"value":"hdfs:\/\/hdfs.prod:54310\/user\/ashwanth\/hadoop-with-mesos-2.6.0-cdh5.4.4.tar.gz"}}],"sandbox_directory":"\/var\/lib\/mesos\/slaves\/20150706-075218-1611773194-5050-28439-S473\/frameworks\/20150706-075218-1611773194-5050-28439-4532\/executors\/executor_Task_Tracker_4129\/runs\/c26f52d4-4055-46fa-b999-11d73f2096dd","user":"hadoop"} I0818 05:36:35.059806 24428 fetcher.cpp:364] Fetching URI 'hdfs://hdfs.prod:54310/user/ashwanth/hadoop-with-mesos-2.6.0-cdh5.4.4.tar.gz' I0818 05:36:35.059821 24428 fetcher.cpp:238] Fetching directly into the sandbox directory I0818 05:36:35.059835 24428 fetcher.cpp:176] Fetching URI 'hdfs://hdfs.prod:54310/user/ashwanth/hadoop-with-mesos-2.6.0-cdh5.4.4.tar.gz' mesos-fetcher: /tmp/mesos-build/mesos-repo/3rdparty/libprocess/3rdparty/stout/include/stout/try.hpp:90: const string& Try::error() const [with T = bool; std::string = std::basic_string]: Assertion `data.isNone()' failed. {noformat} This is, however, a genuine bug in {{src/launcher/fetcher.cpp#L99}}: {code} Try available = hdfs.available(); if (available.isError() || !available.get()) { return Error("Skipping fetch with Hadoop Client as" " Hadoop Client not available: " + available.error()); } {code} The root cause is that (probably) the HDFS client is not available on the slave; however, we do not {{error()}} but rather return a {{false}} result. The bug is exposed in the {{return}} line, where we try to retrieve {{available.error()}} (which is not there - it's just `false`). This was a 'latent' bug that has been exposed by (my) recent refactoring of {{os::shell}} which is used by {{hdfs.available()}} under the covers.
Story points: 1