From 7bffd49adec76b9e6c2fd55a14a800a275307417 Mon Sep 17 00:00:00 2001
From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Date: Sun, 20 Sep 2020 00:29:23 +0900
Subject: rootless-cni-infra: fix flakiness during bringing up lo interface

Fix #7618

This bumps up ROOTLESS_CNI_INFRA_VERSION to 2

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
---
 contrib/rootless-cni-infra/Containerfile      |  2 +-
 contrib/rootless-cni-infra/rootless-cni-infra | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/contrib/rootless-cni-infra/Containerfile b/contrib/rootless-cni-infra/Containerfile
index 5be30ccc9..6bf70d644 100644
--- a/contrib/rootless-cni-infra/Containerfile
+++ b/contrib/rootless-cni-infra/Containerfile
@@ -34,4 +34,4 @@ COPY rootless-cni-infra /usr/local/bin
 ENV CNI_PATH=/opt/cni/bin
 CMD ["sleep", "infinity"]
 
-ENV ROOTLESS_CNI_INFRA_VERSION=1
+ENV ROOTLESS_CNI_INFRA_VERSION=2
diff --git a/contrib/rootless-cni-infra/rootless-cni-infra b/contrib/rootless-cni-infra/rootless-cni-infra
index f6622b23c..5cb43621d 100755
--- a/contrib/rootless-cni-infra/rootless-cni-infra
+++ b/contrib/rootless-cni-infra/rootless-cni-infra
@@ -4,6 +4,23 @@ set -eu
 ARG0="$0"
 BASE="/run/rootless-cni-infra"
 
+wait_unshare_net() {
+	pid="$1"
+	# NOTE: busybox shell doesn't support the `for ((i=0; i < $MAX; i++)); do foo; done` statement
+	i=0
+	while :; do
+		if [ "$(readlink /proc/self/ns/net)" != "$(readlink /proc/${pid}/ns/net)" ]; then
+			break
+		fi
+		sleep 0.1
+		if [ $i -ge 10 ]; then
+			echo >&2 "/proc/${pid}/ns/net cannot be unshared"
+			exit 1
+		fi
+		i=$((i + 1))
+	done
+}
+
 # CLI subcommand: "alloc $CONTAINER_ID $NETWORK_NAME $POD_NAME"
 cmd_entrypoint_alloc() {
 	if [ "$#" -ne 3 ]; then
@@ -24,6 +41,7 @@ cmd_entrypoint_alloc() {
 	else
 		unshare -n sleep infinity &
 		pid="$!"
+		wait_unshare_net "${pid}"
 		echo "${pid}" >"${dir}/pid"
 		nsenter -t "${pid}" -n ip link set lo up
 	fi
-- 
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