From 2e80c670e1afd4f8c35bc8ac71b29ebd358596c2 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Wed, 23 Sep 2026 12:31:33 +0000
Subject: [PATCH] Remove a stale containerd pid on start

/run is not a tmpfs, so an unclean shutdown leaves
/run/docker/containerd/containerd.pid behind. If another process has
been given that pid by the time dockerd starts, dockerd takes it for a
running containerd, never starts one and gives up with "timeout waiting
for containerd to start". Nothing can be running yet when
init-config-kasm runs, so remove the file there.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RmwHZxdRuWgp9chBZTZTMn
---
 readme-vars.yml                                  | 1 +
 root/etc/s6-overlay/s6-rc.d/init-config-kasm/run | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/readme-vars.yml b/readme-vars.yml
index 17994e7..aae42e6 100644
--- a/readme-vars.yml
+++ b/readme-vars.yml
@@ -130,6 +130,7 @@ init_diagram: |
   "kasm:latest" <- Base Images
 # changelog
 changelogs:
+  - {date: "23.09.26:", desc: "Remove a stale containerd pid on start, which could keep dockerd from starting after an unclean shutdown."}
   - {date: "04.08.26:", desc: "Give kasm_manager a healthcheck start period so a cold start does not leave kasm_proxy created but never started."}
   - {date: "16.04.26:", desc: "Update for 1.18.1 release. Use rolling service images. Bump docker to v29."}
   - {date: "13.11.25:", desc: "Pin docker to v28 to avoid API deprecation issues."}
diff --git a/root/etc/s6-overlay/s6-rc.d/init-config-kasm/run b/root/etc/s6-overlay/s6-rc.d/init-config-kasm/run
index 24015ae..b040e7c 100755
--- a/root/etc/s6-overlay/s6-rc.d/init-config-kasm/run
+++ b/root/etc/s6-overlay/s6-rc.d/init-config-kasm/run
@@ -13,6 +13,10 @@ if [[ -S /var/run/docker.sock ]]; then
   rm -f /var/run/docker.sock
 fi
 
+# Clean up old containerd pid, which dockerd takes for a running containerd if
+# another process has been given that pid since an unclean shutdown
+rm -f /var/run/docker/containerd/containerd.pid
+
 # Login to Dockerhub
 if [[ -n "${DOCKER_HUB_USERNAME}" ]]; then
     docker login --username "${DOCKER_HUB_USERNAME}" --password "${DOCKER_HUB_PASSWORD}"