gristlabs_grist-core/sandbox/docker_entrypoint.sh

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#!/usr/bin/env bash
set -Eeuo pipefail
# Runs the command provided as arguments, but attempts to configure permissions first.
important_read_dirs=("/grist" "/persist")
write_dir="/persist"
current_user_id=$(id -u)
# We want to avoid running Grist as root if possible.
# Try to setup permissions and de-elevate to a normal user.
if [[ $current_user_id == 0 ]]; then
target_user=${GRIST_DOCKER_USER:-grist}
target_group=${GRIST_DOCKER_GROUP:-grist}
# Make sure the target user owns everything that Grist needs write access to.
find $write_dir ! -user "$target_user" -exec chown "$target_user" "{}" +
# Restart as the target user, replacing the current process (replacement is needed for security).
# Alternative tools to setpriv are: chroot, gosu.
# Need to use `exec` to close the parent shell, to avoid vulnerabilities: https://github.com/tianon/gosu/issues/37
exec setpriv --reuid "$target_user" --regid "$target_group" --init-groups /usr/bin/env bash "$0" "$@"
fi
# Validate that this user has access to the top level of each important directory.
# There might be a benefit to testing individual files, but this is simpler as the dir may start empty.
for dir in "${important_read_dirs[@]}"; do
if ! { test -r "$dir" ;} ; then
echo "Invalid permissions, cannot read '$dir'. Aborting." >&2
exit 1
fi
done
for dir in "${important_write_dirs[@]}"; do
if ! { test -r "$dir" && test -w "$dir" ;} ; then
echo "Invalid permissions, cannot write '$dir'. Aborting." >&2
exit 1
fi
done
exec /usr/bin/tini -s -- "$@"