auto remount noexec volume

auto_remount_noexec_volume.md

start a contaniner:

$  docker run --rm -ti --privileged alpine:latest sh

next, run code within a container

setup:

$ apk --no-cache add xfsprogs util-linux 
$ dd if=/dev/zero of=/xfs.img bs=1M count=100
$ mkfs.xfs /xfs.img
$ mkdir -p /var/lib/docker
$ mount -o noexec,nodev /xfs.img /var/lib/docker

simulate git checkout:

$ cd /var/lib/docker
$ mkdir -p builds/bin
$ printf '#!/bin/sh\nset -ex\ndate\n' > builds/bin/run.sh
$ chmod +x builds/bin/run.sh
$ cd builds

run script:

$ ./bin/run.sh
sh: ./bin/run.sh: Permission denied

discover and remount noexec volume by current path:

$ findmnt -lnf -o target,options -T . | awk '$2 ~ /noexec/ {print $1}' | xargs -rt -- mount -o remount,exec
mount -o remount,exec /var/lib/docker

re-run script:

$ ./bin/run.sh
+ date
Tue Nov  9 20:06:12 UTC 2021

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