Ahmed Hussein created HADOOP-16810:
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Summary: Increase entropy to improve cryptographic randomness on
precommit Linux VMs
Key: HADOOP-16810
URL: https://issues.apache.org/jira/browse/HADOOP-16810
Project: Hadoop Common
Issue Type: Bug
Reporter: Ahmed Hussein
Assignee: Ahmed Hussein
I was investigating a JUnit test (MAPREDUCE-7079
:TestMRIntermediateDataEncryption is failing in precommit builds) that was
consistently hanging on Linux VMs and failing Mapreduce pre-builds.
I found that the test hangs slows or hangs indefinitely whenever Java reads the
random file.
I explored two different ways to get that test case to work properly on my
local Linux VM running rel7:
# To install "haveged" and "rng-tools" on the virtual machine running Rel7.
Then, start rngd service {{sudo service rngd start}} . This will fix the
problem for all the components on the image including java, native and any
other component.
# Change java configuration to load urandom
{code:bash}
sudo vim $JAVA_HOME/jre/lib/security/java.security
## Change the line “securerandom.source=file:/dev/random” to read:
securerandom.source=file:/dev/./urandom
{code}
The first solution is better because this will fix the problem for everything
that requires SSL/TLS or other services that depend upon encryption.
Since the precommit build runs on Docker, then it would be best to mount
{{/dev/urandom}} from the host as {{/dev/random}} into the container:
{code:java}
docker run -v /dev/urandom:/dev/random
{code}
For Yetus, we need to add the mount to the {{DOCKER_EXTRAARGS}} as follows:
{code:java}
DOCKER_EXTRAARGS+=("-v" "/dev/urandom:/dev/random")
{code}
...
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