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Fix hanging start-stop-daemon in footloose Alpine #3436

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merged 1 commit into from
Aug 29, 2023

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@twz123 twz123 commented Aug 29, 2023

Description

Some distributions package Docker in a way that allows for a vast number of open file descriptors, often achieved through systemd's LimitNOFILE=infinity configuration. This situation leads to start-stop-daemon appearing to hang, consequently blocking the OpenRC init sequence. However, the issue is not an actual hang; rather, it attempts to close all open file descriptors, resulting in a loop with approximately one billion iterations of the close() syscall. This behavior effectively renders the footloose machine unable to boot.

Mitigate this by setting the open file descriptor limit to 1 Mi in OpenRC's rc.conf.

See:

Type of change

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Documentation update

How Has This Been Tested?

  • Manual test
  • Auto test added

Checklist:

  • My code follows the style guidelines of this project
  • My commit messages are signed-off
  • I have performed a self-review of my own code
  • I have commented my code, particularly in hard-to-understand areas
  • I have made corresponding changes to the documentation
  • My changes generate no new warnings
  • I have added tests that prove my fix is effective or that my feature works
  • New and existing unit tests pass locally with my changes
  • Any dependent changes have been merged and published in downstream modules
  • I have checked my code and corrected any misspellings

Some distributions package Docker in a way that allows for a vast
number of open file descriptors, often achieved through systemd's
`LimitNOFILE=infinity` configuration. This situation leads to start-
stop-daemon appearing to hang, consequently blocking the OpenRC
init sequence. However, the issue is not an actual hang; rather, it
attempts to close all open file descriptors, resulting in a loop with
approximately one billion iterations of the close() syscall. This
behavior effectively renders the footloose machine unable to boot.

Mitigate this by setting the open file descriptor limit to 1 Mi in
OpenRC's rc.conf.

Signed-off-by: Tom Wieczorek <[email protected]>
Link: moby/moby@8db6109
Link: https://github.com/OpenRC/openrc/blob/eb8831a1416ab2ee8123b3add78421c2aa316b39/src/start-stop-daemon/start-stop-daemon.c#L1104-L1105
@twz123 twz123 added chore area/smoke-tests backport/release-1.27 PR that needs to be backported/cherrypicked to release-1.27 branch labels Aug 29, 2023
@twz123 twz123 requested a review from a team as a code owner August 29, 2023 12:30
@twz123 twz123 requested review from ncopa and kke August 29, 2023 12:30
@twz123 twz123 merged commit 55dceaf into k0sproject:main Aug 29, 2023
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@twz123 twz123 deleted the footloose-max-fds branch August 29, 2023 13:18
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k0s-bot commented Aug 29, 2023

Successfully created backport PR for release-1.27:

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3 participants