Runit System Port for k3s server #12733
e-dong
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Are you aware of any other distros that use runit as their init system? I've never seen it used outside containers. |
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I can think of Void Linux, antix, and devuan right now. |
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I am in the same situation where I would love to see support for I have created a patch for the For testing I host the full script locally on a webserver and have get.k3s.io point to that local ip. If that patch looks ok and if you are willing to support |
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This looks great, thanks for sharing! Definitely more complete than my simple example. |
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After more testing I have created an updated version. I has some small changes, since the Patch root@k3scp1 ~# cat k3s.v2.patch
diff -Naur a/get.k3s.io b/get.k3s.io
--- a/get.k3s.io 2026-02-19 18:51:28.463845017 +0100
+++ b/get.k3s.io 2026-02-19 22:37:39.614584528 +0100
@@ -124,6 +124,10 @@
HAS_SYSTEMD=true
return
fi
+ if [ -x /usr/bin/runit ] || [ -d /etc/runit ]; then
+ HAS_RUNIT=true
+ return
+ fi
fatal 'Can not find systemd or openrc to use as a process supervisor for k3s'
}
@@ -257,6 +261,13 @@
$SUDO mkdir -p /etc/rancher/k3s
FILE_K3S_SERVICE=/etc/init.d/${SYSTEM_NAME}
FILE_K3S_ENV=/etc/rancher/k3s/${SYSTEM_NAME}.env
+ elif [ "${HAS_RUNIT}" = true ]; then
+ # Runit stores its definitions here
+ RUNIT_SV_DIR="/etc/sv/${SYSTEM_NAME}"
+ $SUDO mkdir -p $RUNIT_SV_DIR
+ FILE_K3S_SERVICE="${RUNIT_SV_DIR}/run"
+ FILE_K3S_LOG_SERVICE="${RUNIT_SV_DIR}/log/run"
+ FILE_K3S_ENV="${RUNIT_SV_DIR}/conf" # We'll use a conf file for env vars
fi
# --- get hash of config & exec for currently installed k3s ---
@@ -814,6 +825,17 @@
[ -x $service ] && $service stop
done
+for service in /etc/sv/k3s; do
+ if [ -d "$service" ]; then
+ # Tell the supervisor to kill the processes
+ sv stop "$service"
+ sv stop "$service/log"
+
+ # Now that it's quiet, remove the link so it stays gone
+ rm -f "/var/service/$(basename $service)"
+ fi
+done
+
pschildren() {
ps -e -o ppid= -o pid= | \
sed -e 's/^\s*//g; s/\s\s*/\t/g;' | \
@@ -958,6 +980,8 @@
rm -rf /var/lib/kubelet
rm -f ${BIN_DIR}/k3s
rm -f ${KILLALL_K3S_SH}
+sleep 3
+rm -rf /etc/sv/k3s
if type yum >/dev/null 2>&1; then
yum remove -y k3s-selinux
@@ -1078,10 +1102,53 @@
EOF
}
+# --- write runit service file ---
+create_runit_service_file() {
+ info "runit: Creating service directory ${RUNIT_SV_DIR}"
+ $SUDO mkdir -p "${RUNIT_SV_DIR}/log"
+
+ info "runit: Creating service file ${FILE_K3S_SERVICE}"
+ $SUDO tee ${FILE_K3S_SERVICE} >/dev/null << EOF
+#!/bin/sh
+# Ensure the entire mount tree is shared for Cilium/K3s
+mount --make-rshared /
+mountpoint -q /sys/fs/bpf || mount -t bpf bpf /sys/fs/bpf
+/sbin/modprobe br_netfilter
+/sbin/modprobe overlay
+
+# LimitNOFILE
+ulimit -n 1048576
+# LimitNPROC
+#ulimit -u unlimited
+# LimitCORE
+ulimit -c unlimited
+
+# For the processes (NPROC), since dash is a hater,
+# we use the 'prlimit' command. It's part of util-linux.
+# It can set the HARD and SOFT limits directly on a process.
+
+# Load environment variables
+[ -r ./conf ] && . ./conf
+
+exec 2>&1
+exec prlimit --nproc=unlimited ${BIN_DIR}/k3s ${CMD_K3S_EXEC}
+EOF
+ $SUDO chmod 0755 ${FILE_K3S_SERVICE}
+
+ info "runit: Creating logger file ${FILE_K3S_LOG_SERVICE}"
+ $SUDO tee ${FILE_K3S_LOG_SERVICE} >/dev/null << EOF
+#!/bin/sh
+mkdir -p /var/log/${SYSTEM_NAME}
+exec svlogd -tt /var/log/${SYSTEM_NAME}
+EOF
+ $SUDO chmod 0755 ${FILE_K3S_LOG_SERVICE}
+}
+
# --- write systemd or openrc service file ---
create_service_file() {
[ "${HAS_SYSTEMD}" = true ] && create_systemd_service_file && restore_systemd_service_file_context
[ "${HAS_OPENRC}" = true ] && create_openrc_service_file
+ [ "${HAS_RUNIT}" = true ] && create_runit_service_file
return 0
}
@@ -1118,6 +1185,19 @@
$SUDO ${FILE_K3S_SERVICE} restart
}
+runit_enable() {
+ info "runit: Enabling ${SYSTEM_NAME} via /var/service"
+ $SUDO ln -sf ${RUNIT_SV_DIR} /var/service/
+}
+
+runit_start() {
+ info "runit: Starting ${SYSTEM_NAME}"
+ # Wait a moment to the the "runsv supervisor" settle
+ sleep 5
+ # We don't need to start the service, since the link creation in enable takes care of that
+ $SUDO sv status ${SYSTEM_NAME}
+}
+
has_working_xtables() {
if $SUDO sh -c "command -v \"$1-save\"" 1> /dev/null && $SUDO sh -c "command -v \"$1-restore\"" 1> /dev/null; then
if $SUDO $1-save 2>/dev/null | grep -q '^-A CNI-HOSTPORT-MASQ -j MASQUERADE$'; then
@@ -1141,6 +1221,7 @@
[ "${HAS_SYSTEMD}" = true ] && systemd_enable
[ "${HAS_OPENRC}" = true ] && openrc_enable
+ [ "${HAS_RUNIT}" = true ] && runit_enable
[ "${INSTALL_K3S_SKIP_START}" = true ] && return
@@ -1158,6 +1239,7 @@
[ "${HAS_SYSTEMD}" = true ] && systemd_start
[ "${HAS_OPENRC}" = true ] && openrc_start
+ [ "${HAS_RUNIT}" = true ] && runit_start
return 0
}Here is an example with live patching. root@k3scp1 ~# curl -sfL https://get.k3s.io | patch -f -s -o - -i k3s.v2.patch | env INSTALL_K3S_VERSION=v1.35.0+k3s1 INSTALL_K3S_EXEC=server sh -s - --disable servicelb --disable traefik --node-taint node.cilium.io/agent-not-ready=true:NoSchedule --kube-apiserver-arg default-not-ready-toleration-seconds=30 --kube-apiserver-arg default-unreachable-toleration-seconds=30 --kube-controller-arg node-monitor-period=20s --kube-controller-arg node-monitor-grace-period=20s --kubelet-arg node-status-update-frequency=5s --kubelet-arg resolv-conf= --flannel-backend=none --disable-network-policy --disable-kube-proxy --cluster-cidr=fd0:cafe:52::/56,10.52.0.0/16 --service-cidr=fd0:cafe:53::/112,10.53.0.0/16 --node-external-ip=2a02:174:318:6140::11,10.0.0.11 --kubelet-arg=node-ip="2a02:174:318:6140::11,10.0.0.11" --node-ip=2a02:174:318:6140::11,10.0.0.11
[INFO] Using v1.35.0+k3s1 as release
[INFO] Downloading hash https://github.com/k3s-io/k3s/releases/download/v1.35.0+k3s1/sha256sum-arm64.txt
[INFO] Downloading binary https://github.com/k3s-io/k3s/releases/download/v1.35.0+k3s1/k3s-arm64
[INFO] Verifying binary download
[INFO] Installing k3s to /usr/local/bin/k3s
[INFO] Skipping installation of SELinux RPM
[INFO] Creating /usr/local/bin/kubectl symlink to k3s
[INFO] Creating /usr/local/bin/crictl symlink to k3s
[INFO] Creating /usr/local/bin/ctr symlink to k3s
[INFO] Creating killall script /usr/local/bin/k3s-killall.sh
[INFO] Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO] env: Creating environment file /etc/sv/k3s/conf
[INFO] runit: Creating service directory /etc/sv/k3s
[INFO] runit: Creating service file /etc/sv/k3s/run
[INFO] runit: Creating logger file /etc/sv/k3s/log/run
[INFO] runit: Enabling k3s via /var/service
[INFO] runit: Starting k3s
run: k3s: (pid 1096) 2s; run: log: (pid 1095) 2s
root@k3scp1 ~# cat /proc/(pgrep -f "k3s server")/limits
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size unlimited unlimited bytes
Max resident set unlimited unlimited bytes
Max processes unlimited unlimited processes
Max open files 1000000 1000000 files
Max locked memory 8388608 8388608 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 14775 14775 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us
root@k3scp1 ~# kubectl get node -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k3scp1.test.lab NotReady control-plane 39s v1.35.0+k3s1 2a02:174:318:6140::11 2a02:174:318:6140::11 Void Linux 6.18.12-msc_1 containerd://2.1.5-k3s1Will a pull request be accepted to support |
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It looks like k3s officially supports
systemdoropenrcas the init system. I use Artix (Arch without systemd) with the runit system.I wanted to share my port to make a runit service.
/etc/runit/sv/k3s/run/etc/runit/sv/k3s/log/runTo enable on startup,
ln -s /etc/runit/sv/k3s /run/runit/service/k3sUse
sv status k3s/sv start k3s/sv stop k3sBeta Was this translation helpful? Give feedback.
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