'How to use rkt as container runtime instead of docker for kubernetes?

I tried using rktlet(https://github.com/kubernetes-incubator/rktlet/blob/master/docs/getting-started-guide.md)

But when I try to 

kubelet --cgroup-driver=systemd \
> --container-runtime=remote \
> --container-runtime-endpoint=/var/run/rktlet.sock \
> --image-service-endpoint=/var/run/rktlet.sock

I am getting the below errors

Flag --cgroup-driver has been deprecated, This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.
I0320 13:10:21.661373    3116 server.go:407] Version: v1.13.4
I0320 13:10:21.663411    3116 plugins.go:103] No cloud provider specified.
W0320 13:10:21.664635    3116 server.go:552] standalone mode, no API client
W0320 13:10:21.669757    3116 server.go:464] No api server defined - no events will be sent to API server.
I0320 13:10:21.669791    3116 server.go:666] --cgroups-per-qos enabled, but --cgroup-root was not specified.  defaulting to /
I0320 13:10:21.670018    3116 container_manager_linux.go:248] container manager verified user specified cgroup-root exists: []
I0320 13:10:21.670038    3116 container_manager_linux.go:253] Creating Container Manager object based on Node Config: {RuntimeCgroupsName: SystemCgroupsName: KubeletCgroupsName: ContainerRuntime:remote CgroupsPerQOS:true CgroupRoot:/ CgroupDriver:systemd KubeletRootDir:/var/lib/kubelet ProtectKernelDefaults:false NodeAllocatableConfig:{KubeReservedCgroupName: SystemReservedCgroupName: EnforceNodeAllocatable:map[pods:{}] KubeReserved:map[] SystemReserved:map[] HardEvictionThresholds:[{Signal:nodefs.inodesFree Operator:LessThan Value:{Quantity:<nil> Percentage:0.05} GracePeriod:0s MinReclaim:<nil>} {Signal:imagefs.available Operator:LessThan Value:{Quantity:<nil> Percentage:0.15} GracePeriod:0s MinReclaim:<nil>} {Signal:memory.available Operator:LessThan Value:{Quantity:100Mi Percentage:0} GracePeriod:0s MinReclaim:<nil>} {Signal:nodefs.available Operator:LessThan Value:{Quantity:<nil> Percentage:0.1} GracePeriod:0s MinReclaim:<nil>}]} QOSReserved:map[] ExperimentalCPUManagerPolicy:none ExperimentalCPUManagerReconcilePeriod:10s ExperimentalPodPidsLimit:-1 EnforceCPULimits:true CPUCFSQuotaPeriod:100ms}
I0320 13:10:21.670125    3116 container_manager_linux.go:272] Creating device plugin manager: true
I0320 13:10:21.670151    3116 state_mem.go:36] [cpumanager] initializing new in-memory state store
I0320 13:10:21.670254    3116 state_mem.go:84] [cpumanager] updated default cpuset: ""
I0320 13:10:21.670271    3116 state_mem.go:92] [cpumanager] updated cpuset assignments: "map[]"
W0320 13:10:21.672059    3116 util_unix.go:77] Using "/var/run/rktlet.sock" as endpoint is deprecated, please consider using full url format "unix:///var/run/rktlet.sock".
W0320 13:10:21.672124    3116 util_unix.go:77] Using "/var/run/rktlet.sock" as endpoint is deprecated, please consider using full url format "unix:///var/run/rktlet.sock".
E0320 13:10:21.673168    3116 remote_runtime.go:72] Version from runtime service failed: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService
E0320 13:10:21.673228    3116 kuberuntime_manager.go:184] Get runtime version failed: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService
F0320 13:10:21.673249    3116 server.go:261] failed to run Kubelet: failed to create kubelet: rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService

How do I create a kube cluster using rkt? Please help.

kuberneteskubeletrkt


Solution 1:[1]

That's the way to run Rktlet. However, Rktlet is still pretty experimental and I believe it's not being actively developed either. The last commit as per this writing was in 05/2018.

You can try running it the other way as described here or here. Basically, use --container-runtime=rkt, --rkt-path=PATH_TO_RKT_BINARY, etc. on the kubelet.

Is there a reason why you are need rkt? Note that --container-runtime=rkt is deprecated in the latest Kubernetes but should still work (1.13 as of this writing).

Solution 2:[2]

Not sure about unknown service runtime.v1alpha2.RuntimeService but unknown service runtime.v1alpha2.ImageService in my case helps to remove "cri" from disabled_plugins in /etc/containerd/config.toml config:

#disabled_plugins = ["cri"]
disabled_plugins = []

and restart containerd service systemctl restart containerd.service

Solution 3:[3]

You can check ctr plugin ls output for some plugin in error state:

ctr plugin ls
TYPE                            ID                       PLATFORMS      STATUS
io.containerd.content.v1        content                  -              ok
io.containerd.snapshotter.v1    aufs                     linux/amd64    skip
io.containerd.snapshotter.v1    btrfs                    linux/amd64    skip
io.containerd.snapshotter.v1    devmapper                linux/amd64    error
io.containerd.snapshotter.v1    native                   linux/amd64    ok
io.containerd.snapshotter.v1    overlayfs                linux/amd64    ok
io.containerd.snapshotter.v1    zfs                      linux/amd64    skip
io.containerd.metadata.v1       bolt                     -              ok
io.containerd.differ.v1         walking                  linux/amd64    ok
io.containerd.gc.v1             scheduler                -              ok
io.containerd.service.v1        introspection-service    -              ok
io.containerd.service.v1        containers-service       -              ok
io.containerd.service.v1        content-service          -              ok
io.containerd.service.v1        diff-service             -              ok
io.containerd.service.v1        images-service           -              ok
io.containerd.service.v1        leases-service           -              ok
io.containerd.service.v1        namespaces-service       -              ok
io.containerd.service.v1        snapshots-service        -              ok
io.containerd.runtime.v1        linux                    linux/amd64    ok
io.containerd.runtime.v2        task                     linux/amd64    ok
io.containerd.monitor.v1        cgroups                  linux/amd64    ok
io.containerd.service.v1        tasks-service            -              ok
io.containerd.internal.v1       restart                  -              ok
io.containerd.grpc.v1           containers               -              ok
io.containerd.grpc.v1           content                  -              ok
io.containerd.grpc.v1           diff                     -              ok
io.containerd.grpc.v1           events                   -              ok
io.containerd.grpc.v1           healthcheck              -              ok
io.containerd.grpc.v1           images                   -              ok
io.containerd.grpc.v1           leases                   -              ok
io.containerd.grpc.v1           namespaces               -              ok
io.containerd.internal.v1       opt                      -              ok
io.containerd.grpc.v1           snapshots                -              ok
io.containerd.grpc.v1           tasks                    -              ok
io.containerd.grpc.v1           version                  -              ok

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Rico
Solution 2 Oleg Neumyvakin
Solution 3 Oleg Neumyvakin

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