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kata-deploy: Modify containerd config atomically

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the kata-deploy pod can be restarted/interrupted at any time which might
lead to partially modified files. Let's use a loop to configure
containerd to minimize the probability of partial modification.

Note this is still not perfect as there is a short non-atomic part, but
given the order of changes it shouldn't result in partially modified
files.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
This commit is contained in:
Lukáš Doktor 2025-01-23 17:51:43 +01:00
parent 8bf3582e83
commit f47d643b82
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1 changed files with 28 additions and 10 deletions
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30
tools/packaging/kata-deploy/scripts/kata-deploy.sh
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@ -592,14 +592,14 @@ function configure_containerd_runtime() {
local runtime="kata-${adjusted_shim_to_multi_install}"
local configuration="configuration-${shim}"
local pluginid=cri
local configuration_file="${containerd_conf_file}"
local configuration_file="$3"
# Properly set the configuration file in case drop-in files are supported
if [ $use_containerd_drop_in_conf_file = "true" ]; then
configuration_file="/host${containerd_drop_in_conf_file}"
fi
local containerd_root_conf_file="$containerd_conf_file"
local containerd_root_conf_file="$configuration_file"
if [[ "$1" =~ ^(k0s-worker|k0s-controller)$ ]]; then
containerd_root_conf_file="/etc/containerd/containerd.toml"
fi
@ -649,15 +649,33 @@ function configure_containerd() {
mkdir -p /etc/containerd/
# To avoid problems when this pod gets re-created let's be a bit paranoiac
# and try to configure/backup the most recent configuration more-less
# atomically. This shouldn't be that needed for drop-in configuration
# but shouldn't harm either.
local tmp_config_file=$(mktemp)
( for i in {1..10}; do
local pre_config="$(cat "$containerd_conf_file")"
echo "$pre_config" > "$tmp_config_file"
for shim in "${shims[@]}"; do
configure_containerd_runtime "$1" "$shim" "$tmp_config_file"
done
if [ "$(cat "$containerd_conf_file")" == "$pre_config" ]; then
# Nobody modified the containerd file, write our changes in
# least dangerous way (no atomicity of this section...)
if [ $use_containerd_drop_in_conf_file = "false" ] && [ -f "$containerd_conf_file" ]; then
# only backup in case drop-in files are not supported, and when doing the backup
# only do it if a backup doesn't already exist (don't override original)
cp -n "$containerd_conf_file" "$containerd_conf_file_backup"
fi
for shim in "${shims[@]}"; do
configure_containerd_runtime "$1" "$shim"
done
mv -f "$tmp_config_file" "$containerd_conf_file"
exit 0
fi
sleep $(($RANDOM / 1000))
done ) || die "Failed to configure containerd in 10 iterations, is someone else modifying ${containerd_conf_file}?"
rm -f "$tmp_config_file"
if [ $use_containerd_drop_in_conf_file = "true" ]; then
tomlq -i -t $(printf '.imports|=.+["%s"]' ${containerd_drop_in_conf_file}) ${containerd_conf_file}