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Diffstat (limited to 'kubernetes.md')
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diff --git a/kubernetes.md b/kubernetes.md deleted file mode 100644 index a88a76a38..000000000 --- a/kubernetes.md +++ /dev/null @@ -1,105 +0,0 @@ -# Running CRI-O on kubernetes cluster - -## Switching runtime from docker to CRI-O - -In standard docker kubernetes cluster, kubelet is running on each node as systemd service and is taking care of communication between runtime and api service. -It is reponsible for starting microservices pods (such as `kube-proxy`, `kubedns`, etc. - they can be different for various ways of deploying k8s) and user pods. -Configuration of kubelet determines which runtime is used and in what way. - -Kubelet itself is executed in docker container (as we can see in `kubelet.service`), but, what is important, **it's not** a kubernetes pod (at least for now), -so we can keep kubelet running inside container (as well as directly on the host), and regardless of this, run pods in chosen runtime. - -Below, you can find an instruction how to switch one or more nodes on running kubernetes cluster from docker to CRI-O. - -### Preparing crio - -You must prepare and install `crio` on each node you would like to switch. Here's the list of files that must be provided: - -| File path | Description | Location | -|--------------------------------------------|----------------------------|-----------------------------------------------------| -| `/etc/crio/crio.conf` | crio configuration | Generated on cri-o `make install` | -| `/etc/crio/seccomp.conf` | seccomp config | Example stored in cri-o repository | -| `/etc/containers/policy.json` | containers policy | Example stored in cri-o repository | -| `/bin/{crio, runc}` | `crio` and `runc` binaries | Built from cri-o repository | -| `/usr/local/libexec/crio/conmon` | `conmon` binary | Built from cri-o repository | -| `/opt/cni/bin/{flannel, bridge,...}` | CNI plugins binaries | Can be built from sources `containernetworking/cni` | -| `/etc/cni/net.d/10-mynet.conf` | Network config | Example stored in [README file](README.md) | - -`crio` binary can be executed directly on host, inside the container or in any way. -However, recommended way is to set it as a systemd service. -Here's the example of unit file: - -``` -# cat /etc/systemd/system/crio.service -[Unit] -Description=CRI-O daemon -Documentation=https://github.com/kubernetes-incubator/cri-o - -[Service] -ExecStart=/bin/crio --runtime /bin/runc --log /root/crio.log --log-level debug -Restart=always -RestartSec=10s - -[Install] -WantedBy=multi-user.target -``` - -### Preparing kubelet -At first, you need to stop kubelet service working on the node: -``` -# systemctl stop kubelet -``` -and stop all kubelet docker containers that are still runing. - -``` -# docker stop $(docker ps | grep k8s_ | awk '{print $1}') -``` - -We have to be sure that `kubelet.service` will start after `crio.service`. -It can be done by adding `crio.service` to `Wants=` section in `/etc/systemd/system/kubelet.service`: - -``` -# cat /etc/systemd/system/kubelet.service | grep Wants -Wants=docker.socket crio.service -``` - -If you'd like to change the way of starting kubelet (e.g. directly on host instead of docker container), you can change it here, but, as mentioned, it's not necessary. - - -Kubelet parameters are stored in `/etc/kubernetes/kubelet.env` file. -``` -# cat /etc/kubernetes/kubelet.env | grep KUBELET_ARGS -KUBELET_ARGS="--pod-manifest-path=/etc/kubernetes/manifests ---pod-infra-container-image=gcr.io/google_containers/pause-amd64:3.0 ---cluster_dns=10.233.0.3 --cluster_domain=cluster.local ---resolv-conf=/etc/resolv.conf --kubeconfig=/etc/kubernetes/node-kubeconfig.yaml ---require-kubeconfig" -``` - -You need to add following parameters to `KUBELET_ARGS`: -* `--experimental-cri=true` - Use Container Runtime Interface. Will be true by default from kubernetes 1.6 release. -* `--container-runtime=remote` - Use remote runtime with provided socket. -* `--container-runtime-endpoint=/var/run/crio.sock` - Socket for remote runtime (default `crio` socket localization). -* `--runtime-request-timeout=10m` - Optional but useful. Some requests, especially pulling huge images, may take longer than default (2 minutes) and will cause an error. - -Kubelet is prepared now. - -## Flannel network -If your cluster is using flannel network, your network configuration should be like: -``` -# cat /etc/cni/net.d/10-mynet.conf -{ - "name": "mynet", - "type": "flannel" -} -``` -Then, kubelet will take parameters from `/run/flannel/subnet.env` - file generated by flannel kubelet microservice. - -## Starting kubelet with CRI-O -Start crio first, then kubelet. If you created `crio` service: -``` -# systemctl start crio -# systemctl start kubelet -``` - -You can follow the progress of preparing node using `kubectl get nodes` or `kubectl get pods --all-namespaces` on kubernetes master. |