Validated on Version

-$ k3s version v1.33.4-rc1+k3s1 (148243c4)

Environment Details

Infrastructure
Cloud EC2 instance

Node(s) CPU architecture, OS, and Version:
rhel 9.5
AMD

Cluster Configuration:
1 node server

Steps to validate the fix

Install K3s server with docker and container runtime endpoint unix:///var/run/docker.sock
Make sure cri-dockerd is running
Cluster is up and running

Reproduction Issue:

  sudo curl https://get.k3s.io |  sudo INSTALL_K3S_VERSION=v1.31.10+k3s1    sh -s - server --docker --container-runtime-endpoint unix:///var/run/docker.sock


 ming-bind-addr=127.0.0.1:10010"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="cri-dockerd version v0.3.17-k3s1.31 (HEAD)"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Starting cri-dockerd v0.3.17-k3s1.31 (HEAD)"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Connecting to docker on the Endpoint unix:///var/run/docker.sock"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Start docker client with request timeout 0s"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Hairpin mode is set to none"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Loaded network plugin cni"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Docker cri networking managed by network plugin cni"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Setting cgroupDriver systemd"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Docker cri received runtime config &RuntimeConfig{NetworkConfig:&NetworkConfig{PodCidr:,},}"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Starting the GRPC backend for the Docker CRI interface."
. k3s[8396]: time="2025-08-20T13:18:32Z" level=info msg="Start cri-dockerd grpc backend"
. k3s[8396]: time="2025-08-20T13:18:32Z" level=fatal msg="cri-dockerd panic: runtime error: index out of range [1] with length 1" stack="goroutine 448 [running]:\nruntime/debug.Stack()\n\t/usr/local/go/src/runtime/debug/stack.go:26 +0x5e\ngithub.com/k3s-io/k3s/pkg/agent/cridockerd.Run.func1.1()\n\t/go/src/github.com/k3s-io/k3s/pkg/agent/cridockerd/cridockerd.go:39 +0x38\npanic({0x65c0520?, 0xc000fd1818?})\n\t/usr/local/go/src/runtime/panic.go:791 +0x132\ngithub.com/Mirantis/cri-dockerd/backend.getListener({0xc000f26482, 0x0})\n\t/go/pkg/mod/github.com/k3s-io/cri-dockerd@v0.3.17-k3s1.31/backend/daemon.go:58 +0x8f\ngithub.com/Mirantis/cri-dockerd/backend.(*CriDockerService).Start(0xc000f56540)\n\t/go/pkg/mod/github.com/k3s-io/cri-dockerd@v0.3.17-k3s1.31/backend/daemon.go:76 +0x105\ngithub.com/Mirantis/cri-dockerd/cmd.RunCriDockerd(0xc0009acb40, 0xc000cab030)\n\t/go/pkg/mod/github.com/k3s-io/cri-dockerd@v0.3.17-k3s1.31/cmd/server.go:222 +0x851\ngithub.com/Mirantis/cri-dockerd/cmd.NewDockerCRICommand.func1(0xc00045cc08, {0xc000428e80?, 0x4?, 0x69da375?})\n\t/go/pkg/mod/github.com/k3s-io/cri-dockerd@v0.3.17-k3s1.31/cmd/server.go:114 +0x3b5\ngithub.com/spf13/cobra.(*Command).execute(0xc00045cc08, {0xc000428e80, 0x7, 0x8})\n\t/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:989 +0xa91\ngithub.com/spf13/cobra.(*Command).ExecuteC(0xc00045cc08)\n\t/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:1117 +0x3ff\ngithub.com/spf13/cobra.(*Command).Execute(...)\n\t/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:1041\ngithub.com/spf13/cobra.(*Command).ExecuteContext(0x0?, {0x7a0eb30?, 0xc0008dd810?})\n\t/go/pkg/mod/github.com/spf13/cobra@v1.8.1/command.go:1034 +0x47\ngithub.com/k3s-io/k3s/pkg/agent/cridockerd.Run.func1()\n\t/go/src/github.com/k3s-io/k3s/pkg/agent/cridockerd/cridockerd.go:42 +0x45\ncreated by github.com/k3s-io/k3s/pkg/agent/cridockerd.Run in goroutine 1\n\t/go/src/github.com/k3s-io/k3s/pkg/agent/cridockerd/cridockerd.go:36 +0x2da\n"
. systemd[1]: k3s.service: Main process exited, code=exited, status=1/FAILURE
. systemd[1]: k3s.service: Failed with result 'exit-code'.
. systemd[1]: Failed to start Lightweight Kubernetes.

Validation Results:

 
 ~$ k3s -v
k3s version v1.33.4-rc1+k3s1 (148243c4)
 
 
kubectl get nodes -o wide
NAME               STATUS   ROLES                       AGE     VERSION            INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                              KERNEL-VERSION              CONTAINER-RUNTIME
ip-   Ready    control-plane,etcd,master   3m33s   v1.33.4-rc1+k3s1      <none>        SUSE Linux Enterprise Server 15 SP7   6.4.0-150700.53.3-default   docker://27.5.1-ce

~$ kubectl get pods -A
NAMESPACE     NAME                                      READY   STATUS      RESTARTS   AGE
kube-system   coredns-64fd4b4794-h48bh                  1/1     Running     0          81s
kube-system   helm-install-traefik-crd-lz6vm            0/1     Completed   0          81s
kube-system   helm-install-traefik-lpnnv                0/1     Completed   2          81s
kube-system   local-path-provisioner-774c6665dc-jlmhv   1/1     Running     0          81s
kube-system   metrics-server-7bfffcd44-4hpmk            1/1     Running     0          81s
kube-system   svclb-traefik-0cc32572-b7jpf              2/2     Running     0          28s
kube-system   traefik-c98fdf6fb-db66l                   1/1     Running     0          28s

sudo journalctl -eu k3s  | grep "panic"
<empty>

[Release-1.33] - Can't use cri-dockerd (--docker) with --container-runtime-endpoint #12706

Description

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

[Release-1.33] - Can't use cri-dockerd (`--docker`) with `--container-runtime-endpoint` #12706