Add DOCKER_IPTABLES_LEGACY for letting users explicitly pick `iptab…

…les-legacy` via `--env DOCKER_IPTABLES_LEGACY=1`
docker-library · Dec 19, 2023 · adfaf30 · adfaf30
1 parent 0019fcc
commit adfaf30
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Showing 3 changed files with 30 additions and 3 deletions.
diff --git a/24/dind/dockerd-entrypoint.sh b/24/dind/dockerd-entrypoint.sh
diff --git a/25-rc/dind/dockerd-entrypoint.sh b/25-rc/dind/dockerd-entrypoint.sh
diff --git a/dockerd-entrypoint.sh b/dockerd-entrypoint.sh
@@ -144,7 +144,15 @@ if [ "$1" = 'dockerd' ]; then
 	set -- docker-init -- "$@"
 
 	iptablesLegacy=
-	if [ -s /proc/net/ip_tables_names ] || [ -s /proc/net/ip6_tables_names ] || [ -s /proc/net/arp_tables_names ]; then
+	if [ -n "${DOCKER_IPTABLES_LEGACY+x}" ]; then
+		# let users choose explicitly to legacy or not to legacy
+		iptablesLegacy="$DOCKER_IPTABLES_LEGACY"
+		if [ -n "$iptablesLegacy" ]; then
+			modprobe ip_tables || :
+		else
+			modprobe nf_tables || :
+		fi
+	elif [ -s /proc/net/ip_tables_names ] || [ -s /proc/net/ip6_tables_names ] || [ -s /proc/net/arp_tables_names ]; then
 		# https://git.netfilter.org/iptables/tree/iptables/nft-shared.c?id=f5cf76626d95d2c491a80288bccc160c53b44e88#n420
 		# if we already have any "legacy" iptables rules, we should always use legacy (https://github.com/docker-library/docker/pull/468#discussion_r1430804593)
 		iptablesLegacy=1
@@ -166,6 +174,7 @@ if [ "$1" = 'dockerd' ]; then
 		# see https://github.com/docker-library/docker/issues/463 (and the dind Dockerfile where this directory is set up)
 		export PATH="/usr/local/sbin/.iptables-legacy:$PATH"
 	fi
+	iptables --version # so users can see whether it's legacy or not
 
 	uid="$(id -u)"
 	if [ "$uid" != '0' ]; then