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move cron to os init, optimize cron init #285

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move cron to os init, optimize cron init #285

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0 ...ig-end/dependencies.d/init-crontab-config → ...b-config/dependencies.d/init-device-perms
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24 changes: 8 additions & 16 deletions root/etc/s6-overlay/s6-rc.d/init-crontab-config/run
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Original file line number Diff line number Diff line change
@@ -1,33 +1,25 @@
#!/usr/bin/with-contenv bash
# shellcheck shell=bash

# /defaults/crontabs is for user customizable crontabs and they take priority over /etc/crontabs
# /etc/crontabs is for non-user customizable crontabs
# /config/crontabs is only imported if /defaults/crontab is present in image
# in RO environments, no import is done, only /etc/crontabs is active
for cron_user in abc root; do
if [[ -z ${LSIO_READ_ONLY_FS} ]] && [[ -z ${LSIO_NON_ROOT_USER} ]]; then
if [[ -f "/etc/crontabs/${cron_user}" ]]; then
lsiown "${cron_user}":"${cron_user}" "/etc/crontabs/${cron_user}"
crontab -u "${cron_user}" "/etc/crontabs/${cron_user}"
fi
fi

if [[ -f "/defaults/crontabs/${cron_user}" ]]; then
if [[ -f "/defaults/crontabs/${cron_user}" ]] && [[ -z ${LSIO_READ_ONLY_FS} ]] && [[ -z ${LSIO_NON_ROOT_USER} ]]; then
# make folders
mkdir -p \
/config/crontabs

# if crontabs do not exist in config
if [[ ! -f "/config/crontabs/${cron_user}" ]]; then
# copy crontab from system
if crontab -l -u "${cron_user}" >/dev/null 2>&1; then
crontab -l -u "${cron_user}" >"/config/crontabs/${cron_user}"
fi

# if crontabs still do not exist in config (were not copied from system)
# copy crontab from image defaults (using -n, do not overwrite an existing file)
cp -n "/defaults/crontabs/${cron_user}" /config/crontabs/
fi

# set permissions and import user crontabs
lsiown "${cron_user}":"${cron_user}" "/config/crontabs/${cron_user}"

@nemchik nemchik Jun 13, 2026

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This was important. Having the cron user own the crontab in /config meant running as root inside the container required root access on the host. Having abc own the root crontab in /config will allow unprivileged users to modify the container's root cron. If the container has a docker socket that could lead to all kinds of shenanigans.

@aptalca aptalca Jun 14, 2026

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Most downstream images recursively chown config, no point in fighting it.

Custom init also had the same issue and the solution was to put them in a separate mount outside of config, which is not worth the hassle here.

# import user crontabs
crontab -u "${cron_user}" "/config/crontabs/${cron_user}"

lsiown -R abc:abc /config/crontabs
fi
done
0 ...crontab-config/dependencies.d/init-config → ...os-end/dependencies.d/init-crontab-config
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