Jira (FACT-2250) Facter ignores signals while waiting for external commands to run

Charlie Sharpsteen (JIRA)

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Dec 12, 2019, 3:45:04 PM12/12/19

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Charlie Sharpsteen created an issue

Facter /

FACT-2250

Facter ignores signals while waiting for external commands to run

Issue Type:	Bug
Affects Versions:	FACT 3.11.10, FACT 3.14.6
Assignee:	Unassigned
Created:	2019/12/12 12:44 PM
Priority:	Normal
Reporter:	Charlie Sharpsteen

When Facter executes an external command, it will block Ruby signal handlers from firing. This prevents things like SIGINT or SIGQUIT from terminating a Puppet process that is waiting for an external Facter command.

Reproduction Case

Install Puppet 5.5.17 or Puppet 6.11.1 on CentOS 7

yum install -y http://yum.puppetlabs.com/puppet5-release-el-7.noarch.rpm

yum install -y puppet-agent

source /etc/profile.d/puppet-agent.sh

Create a custom fact that logs a message and then executes sleep:

mkdir -p /var/lib/facter/test

cat <<EOF > /var/lib/facter/test/sleepy_fact.rb

Facter.add(:sleepy_fact) do

  setcode do

    Facter.warn('About to sleep for 1000 seconds')

    Facter::Core::Execution.execute('/usr/bin/sleep 1000')

    'took a nice nap'

end

end

EOF

Run puppet facts find and attempt to cancel it with CTRL-C (SIGINT) or CTRL-\ (SIGQUIT)

FACTERLIB=/var/lib/facter/test puppet facts find

Outcome

Like Kieth Richards, Facter cannot be killed by conventional weapons:

# FACTERLIB=/var/lib/facter/test puppet facts find

Warning: Facter: About to sleep for 1000 seconds

^C^C^C^C^C^C^\^\^\^\^\^\^\

Expected Outcome

Facter executing /bin/sleep leaves the Ruby process free to respond to signals in the same way that calling Kernel.sleep does:

# cat <<EOF > /var/lib/facter/test/sleepy_fact.rb

Facter.add(:sleepy_fact) do

  setcode do

    Facter.warn('About to sleep for 1000 seconds')

    ::Kernel.sleep(1000)

    'took a nice nap'

end

end

EOF

# FACTERLIB=/var/lib/facter/test puppet facts find

Warning: Facter: About to sleep for 1000 seconds

^CCancelling Face

Error: Facter: error while resolving custom fact "sleepy_fact": exit

...

# FACTERLIB=/var/lib/facter/test puppet facts find

Warning: Facter: About to sleep for 1000 seconds

^\Error: Facter: error while resolving custom fact "sleepy_fact": SIGQUIT

...

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Charlie Sharpsteen (JIRA)

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Dec 12, 2019, 3:46:03 PM12/12/19

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Charlie Sharpsteen commented on

FACT-2250

Re: Facter ignores signals while waiting for external commands to run

I suspect this is occurring because Facter does not release the Ruby Global Interpreter Lock when dropping into libboost for command execution. The signal handlers need this lock in order to run Ruby code.