From 7d5bec0c2c11a33e71715f5f09fa417c002d109c Mon Sep 17 00:00:00 2001
From: Quentin McGaw <quentin.mcgaw@gmail.com>
Date: Fri, 15 Nov 2024 18:40:03 +0100
Subject: [PATCH] feat(setup/advanced): add kubernetes document

---
 setup/advanced/kubernetes.md | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 setup/advanced/kubernetes.md

diff --git a/setup/advanced/kubernetes.md b/setup/advanced/kubernetes.md
new file mode 100644
index 0000000..2e00249
--- /dev/null
+++ b/setup/advanced/kubernetes.md
@@ -0,0 +1,33 @@
+# Kubernetes
+
+## Common errors
+
+### `adding IPv6 rule: ...: file exists`
+
+This is caused by two factors:
+
+1. Kubernetes shares IP rules across the entire pod even if multiple Gluetun containers are running in the same pod
+1. Abrupt Gluetun exits which can be caused by a node shutdown, power event or just Gluetun hanging at shutdown (I'm working on fixing this)
+
+To resolve this, change the update strategy from `RollingUpdate` to `Recreate` strategy AND add post start command to ensure IP rules are deleted, for example for Wireguard:
+
+```yml
+apiVersion: apps/v1
+kind: Deployment
+spec:
+  strategy:
+    type: Recreate
+    spec:
+      containers:
+        - name: vpn
+          image: qmcgaw/gluetun
+          lifecycle:
+            postStart:
+              exec:
+                command: ["/bin/sh", "-c", "(ip rule del table 51820; ip -6 rule del table 51820) || true"]
+          # ...
+```
+
+**Credits to [@kvangent](https://github.com/kvangent)**
+
+See the [original issue #2521 comment which resolved this](https://github.com/qdm12/gluetun/issues/2521#issuecomment-2453592258)