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Deploying External OpenStack Cloud Provider with Kubeadm
This document describes how to install a single control-plane Kubernetes cluster v1.15 with kubeadm on CentOS, and then deploy an external OpenStack cloud provider and Cinder CSI plugin to use Cinder volumes as persistent volumes in Kubernetes.
Preparation in OpenStack
This cluster runs on OpenStack VMs, so let's create a few things in OpenStack first.
- A project/tenant for this Kubernetes cluster
- A user in this project for Kubernetes, to query node information and attach volumes etc
- A private network and subnet
- A router for this private network and connect it to a public network for floating IPs
- A security group for all Kubernetes VMs
- A VM as a control-plane node and a few VMs as worker nodes
The security group will have the following rules to open ports for Kubernetes.
Control-Plane Node
| Protocol | Port Number | Description |
|---|---|---|
| TCP | 6443 | Kubernetes API Server |
| TCP | 2379-2380 | etcd server client API |
| TCP | 10250 | Kubelet API |
| TCP | 10251 | kube-scheduler |
| TCP | 10252 | kube-controller-manager |
| TCP | 10255 | Read-only Kubelet API |
Worker Nodes
| Protocol | Port Number | Description |
|---|---|---|
| TCP | 10250 | Kubelet API |
| TCP | 10255 | Read-only Kubelet API |
| TCP | 30000-32767 | NodePort Services |
CNI ports on both control-plane and worker nodes
| Protocol | Port Number | Description |
|---|---|---|
| TCP | 179 | Calico BGP network |
| TCP | 9099 | Calico felix (health check) |
| UDP | 8285 | Flannel |
| UDP | 8472 | Flannel |
| TCP | 6781-6784 | Weave Net |
| UDP | 6783-6784 | Weave Net |
CNI specific ports are only required to be opened when that particular CNI plugin is used. In this guide, we will use Weave Net. Only the Weave Net ports (TCP 6781-6784 and UDP 6783-6784), will need to be opened in the security group.
The control-plane node needs at least 2 cores and 4GB RAM. After the VM is launched, verify its hostname and make sure it is the same as the node name in Nova. If the hostname is not resolvable, add it to /etc/hosts.
For example, if the VM is called master1, and it has an internal IP 192.168.1.4. Add that to /etc/hosts and set hostname to master1.
echo "192.168.1.4 master1" >> /etc/hosts hostnamectl set-hostname master1 Install Docker and Kubernetes
Next, we'll follow the official documents to install docker and Kubernetes using kubeadm.
Install Docker following the steps from the container runtime documentation.
Note that it is a best practice to use systemd as the cgroup driver for Kubernetes. If you use an internal container registry, add them to the docker config.
# Install Docker CE ## Set up the repository ### Install required packages. yum install yum-utils device-mapper-persistent-data lvm2 ### Add Docker repository. yum-config-manager \ --add-repo \ https://download.docker.com/linux/centos/docker-ce.repo ## Install Docker CE. yum update && yum install docker-ce-18.06.2.ce ## Create /etc/docker directory. mkdir /etc/docker # Configure the Docker daemon cat > /etc/docker/daemon.json <<EOF { "exec-opts": ["native.cgroupdriver=systemd"], "log-driver": "json-file", "log-opts": { "max-size": "100m" }, "storage-driver": "overlay2", "storage-opts": [ "overlay2.override_kernel_check=true" ] } EOF mkdir -p /etc/systemd/system/docker.service.d # Restart Docker systemctl daemon-reload systemctl restart docker systemctl enable docker Install kubeadm following the steps from the Installing Kubeadm documentation.
cat <<EOF > /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg EOF # Set SELinux in permissive mode (effectively disabling it) # Caveat: In a production environment you may not want to disable SELinux, please refer to Kubernetes documents about SELinux setenforce 0 sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes systemctl enable --now kubelet cat <<EOF > /etc/sysctl.d/k8s.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF sysctl --system # check if br_netfilter module is loaded lsmod | grep br_netfilter # if not, load it explicitly with modprobe br_netfilter The official document about how to create a single control-plane cluster can be found from the Creating a single control-plane cluster with kubeadm documentation.
We'll largely follow that document but also add additional things for the cloud provider. To make things more clear, we'll use a kubeadm-config.yml for the control-plane node. In this config we specify to use an external OpenStack cloud provider, and where to find its config. We also enable storage API in API server's runtime config so we can use OpenStack volumes as persistent volumes in Kubernetes.
apiVersion: kubeadm.k8s.io/v1beta1 kind: InitConfiguration nodeRegistration: kubeletExtraArgs: cloud-provider: "external" --- apiVersion: kubeadm.k8s.io/v1beta2 kind: ClusterConfiguration kubernetesVersion: "v1.15.1" apiServer: extraArgs: enable-admission-plugins: NodeRestriction runtime-config: "storage.k8s.io/v1=true" controllerManager: extraArgs: external-cloud-volume-plugin: openstack extraVolumes: - name: "cloud-config" hostPath: "/etc/kubernetes/cloud-config" mountPath: "/etc/kubernetes/cloud-config" readOnly: true pathType: File networking: serviceSubnet: "10.96.0.0/12" podSubnet: "10.224.0.0/16" dnsDomain: "cluster.local" Now we'll create the cloud config, /etc/kubernetes/cloud-config, for OpenStack. Note that the tenant here is the one we created for all Kubernetes VMs in the beginning. All VMs should be launched in this project/tenant. In addition you need to create a user in this tenant for Kubernetes to do queries. The ca-file is the CA root certificate for OpenStack's API endpoint, for example https://openstack.cloud:5000/v3 At the time of writing the cloud provider doesn't allow insecure connections (skip CA check).
[Global] region=RegionOne username=username password=password auth-url=https://openstack.cloud:5000/v3 tenant-id=14ba698c0aec4fd6b7dc8c310f664009 domain-id=default ca-file=/etc/kubernetes/ca.pem [LoadBalancer] subnet-id=b4a9a292-ea48-4125-9fb2-8be2628cb7a1 floating-network-id=bc8a590a-5d65-4525-98f3-f7ef29c727d5 [BlockStorage] bs-version=v2 [Networking] public-network-name=public ipv6-support-disabled=false Next run kubeadm to initiate the control-plane node
kubeadm init --config=kubeadm-config.yml With the initialization completed, copy admin config to .kube
mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config At this stage, the control-plane node is created but not ready. All the nodes have the taint node.cloudprovider.kubernetes.io/uninitialized=true:NoSchedule and are waiting to be initialized by the cloud-controller-manager.
# kubectl describe no master1 Name: master1 Roles: master ...... Taints: node-role.kubernetes.io/master:NoSchedule node.cloudprovider.kubernetes.io/uninitialized=true:NoSchedule node.kubernetes.io/not-ready:NoSchedule ...... Now deploy the OpenStack cloud controller manager into the cluster, following using controller manager with kubeadm.
Create a secret with the cloud-config for the openstack cloud provider.
kubectl create secret -n kube-system generic cloud-config --from-literal=cloud.conf="$(cat /etc/kubernetes/cloud-config)" --dry-run -o yaml > cloud-config-secret.yaml kubectl apply -f cloud-config-secret.yaml Get the CA certificate for OpenStack API endpoints and put that into /etc/kubernetes/ca.pem.
Create RBAC resources.
kubectl apply -f https://github.com/kubernetes/cloud-provider-openstack/raw/release-1.15/cluster/addons/rbac/cloud-controller-manager-roles.yaml kubectl apply -f https://github.com/kubernetes/cloud-provider-openstack/raw/release-1.15/cluster/addons/rbac/cloud-controller-manager-role-bindings.yaml We'll run the OpenStack cloud controller manager as a DaemonSet rather than a pod. The manager will only run on the control-plane node, so if there are multiple control-plane nodes, multiple pods will be run for high availability. Create openstack-cloud-controller-manager-ds.yaml containing the following manifests, then apply it.
--- apiVersion: v1 kind: ServiceAccount metadata: name: cloud-controller-manager namespace: kube-system --- apiVersion: apps/v1 kind: DaemonSet metadata: name: openstack-cloud-controller-manager namespace: kube-system labels: k8s-app: openstack-cloud-controller-manager spec: selector: matchLabels: k8s-app: openstack-cloud-controller-manager updateStrategy: type: RollingUpdate template: metadata: labels: k8s-app: openstack-cloud-controller-manager spec: nodeSelector: node-role.kubernetes.io/master: "" securityContext: runAsUser: 1001 tolerations: - key: node.cloudprovider.kubernetes.io/uninitialized value: "true" effect: NoSchedule - key: node-role.kubernetes.io/master effect: NoSchedule - effect: NoSchedule key: node.kubernetes.io/not-ready serviceAccountName: cloud-controller-manager containers: - name: openstack-cloud-controller-manager image: docker.io/k8scloudprovider/openstack-cloud-controller-manager:v1.15.0 args: - /bin/openstack-cloud-controller-manager - --v=1 - --cloud-config=$(CLOUD_CONFIG) - --cloud-provider=openstack - --use-service-account-credentials=true - --address=127.0.0.1 volumeMounts: - mountPath: /etc/kubernetes/pki name: k8s-certs readOnly: true - mountPath: /etc/ssl/certs name: ca-certs readOnly: true - mountPath: /etc/config name: cloud-config-volume readOnly: true - mountPath: /usr/libexec/kubernetes/kubelet-plugins/volume/exec name: flexvolume-dir - mountPath: /etc/kubernetes name: ca-cert readOnly: true resources: requests: cpu: 200m env: - name: CLOUD_CONFIG value: /etc/config/cloud.conf hostNetwork: true volumes: - hostPath: path: /usr/libexec/kubernetes/kubelet-plugins/volume/exec type: DirectoryOrCreate name: flexvolume-dir - hostPath: path: /etc/kubernetes/pki type: DirectoryOrCreate name: k8s-certs - hostPath: path: /etc/ssl/certs type: DirectoryOrCreate name: ca-certs - name: cloud-config-volume secret: secretName: cloud-config - name: ca-cert secret: secretName: openstack-ca-cert When the controller manager is running, it will query OpenStack to get information about the nodes and remove the taint. In the node info you'll see the VM's UUID in OpenStack.
# kubectl describe no master1 Name: master1 Roles: master ...... Taints: node-role.kubernetes.io/master:NoSchedule node.kubernetes.io/not-ready:NoSchedule ...... sage:docker: network plugin is not ready: cni config uninitialized ...... PodCIDR: 10.224.0.0/24 ProviderID: openstack:///548e3c46-2477-4ce2-968b-3de1314560a5 Now install your favourite CNI and the control-plane node will become ready.
For example, to install Weave Net, run this command:
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')" Next we'll set up worker nodes.
Firstly, install docker and kubeadm in the same way as how they were installed in the control-plane node. To join them to the cluster we need a token and ca cert hash from the output of control-plane node installation. If it is expired or lost we can recreate it using these commands.
# check if token is expired kubeadm token list # re-create token and show join command kubeadm token create --print-join-command Create kubeadm-config.yml for worker nodes with the above token and ca cert hash.
apiVersion: kubeadm.k8s.io/v1beta2 discovery: bootstrapToken: apiServerEndpoint: 192.168.1.7:6443 token: 0c0z4p.dnafh6vnmouus569 caCertHashes: ["sha256:fcb3e956a6880c05fc9d09714424b827f57a6fdc8afc44497180905946527adf"] kind: JoinConfiguration nodeRegistration: kubeletExtraArgs: cloud-provider: "external" apiServerEndpoint is the control-plane node, token and caCertHashes can be taken from the join command printed in the output of 'kubeadm token create' command.
Run kubeadm and the worker nodes will be joined to the cluster.
kubeadm join --config kubeadm-config.yml At this stage we'll have a working Kubernetes cluster with an external OpenStack cloud provider. The provider tells Kubernetes about the mapping between Kubernetes nodes and OpenStack VMs. If Kubernetes wants to attach a persistent volume to a pod, it can find out which OpenStack VM the pod is running on from the mapping, and attach the underlying OpenStack volume to the VM accordingly.
Deploy Cinder CSI
The integration with Cinder is provided by an external Cinder CSI plugin, as described in the Cinder CSI documentation.
We'll perform the following steps to install the Cinder CSI plugin. Firstly, create a secret with CA certs for OpenStack's API endpoints. It is the same cert file as what we use in cloud provider above.
kubectl create secret -n kube-system generic openstack-ca-cert --from-literal=ca.pem="$(cat /etc/kubernetes/ca.pem)" --dry-run -o yaml > openstack-ca-cert.yaml kubectl apply -f openstack-ca-cert.yaml Then create RBAC resources.
kubectl apply -f https://raw.githubusercontent.com/kubernetes/cloud-provider-openstack/release-1.15/manifests/cinder-csi-plugin/cinder-csi-controllerplugin-rbac.yaml kubectl apply -f https://github.com/kubernetes/cloud-provider-openstack/raw/release-1.15/manifests/cinder-csi-plugin/cinder-csi-nodeplugin-rbac.yaml The Cinder CSI plugin includes a controller plugin and a node plugin. The controller communicates with Kubernetes APIs and Cinder APIs to create/attach/detach/delete Cinder volumes. The node plugin in-turn runs on each worker node to bind a storage device (attached volume) to a pod, and unbind it during deletion. Create cinder-csi-controllerplugin.yaml and apply it to create csi controller.
kind: Service apiVersion: v1 metadata: name: csi-cinder-controller-service namespace: kube-system labels: app: csi-cinder-controllerplugin spec: selector: app: csi-cinder-controllerplugin ports: - name: dummy port: 12345 --- kind: StatefulSet apiVersion: apps/v1 metadata: name: csi-cinder-controllerplugin namespace: kube-system spec: serviceName: "csi-cinder-controller-service" replicas: 1 selector: matchLabels: app: csi-cinder-controllerplugin template: metadata: labels: app: csi-cinder-controllerplugin spec: serviceAccount: csi-cinder-controller-sa containers: - name: csi-attacher image: quay.io/k8scsi/csi-attacher:v1.0.1 args: - "--v=5" - "--csi-address=$(ADDRESS)" env: - name: ADDRESS value: /var/lib/csi/sockets/pluginproxy/csi.sock imagePullPolicy: "IfNotPresent" volumeMounts: - name: socket-dir mountPath: /var/lib/csi/sockets/pluginproxy/ - name: csi-provisioner image: quay.io/k8scsi/csi-provisioner:v1.0.1 args: - "--provisioner=csi-cinderplugin" - "--csi-address=$(ADDRESS)" env: - name: ADDRESS value: /var/lib/csi/sockets/pluginproxy/csi.sock imagePullPolicy: "IfNotPresent" volumeMounts: - name: socket-dir mountPath: /var/lib/csi/sockets/pluginproxy/ - name: csi-snapshotter image: quay.io/k8scsi/csi-snapshotter:v1.0.1 args: - "--connection-timeout=15s" - "--csi-address=$(ADDRESS)" env: - name: ADDRESS value: /var/lib/csi/sockets/pluginproxy/csi.sock imagePullPolicy: Always volumeMounts: - mountPath: /var/lib/csi/sockets/pluginproxy/ name: socket-dir - name: cinder-csi-plugin image: docker.io/k8scloudprovider/cinder-csi-plugin:v1.15.0 args : - /bin/cinder-csi-plugin - "--v=5" - "--nodeid=$(NODE_ID)" - "--endpoint=$(CSI_ENDPOINT)" - "--cloud-config=$(CLOUD_CONFIG)" - "--cluster=$(CLUSTER_NAME)" env: - name: NODE_ID valueFrom: fieldRef: fieldPath: spec.nodeName - name: CSI_ENDPOINT value: unix://csi/csi.sock - name: CLOUD_CONFIG value: /etc/config/cloud.conf - name: CLUSTER_NAME value: kubernetes imagePullPolicy: "IfNotPresent" volumeMounts: - name: socket-dir mountPath: /csi - name: secret-cinderplugin mountPath: /etc/config readOnly: true - mountPath: /etc/kubernetes name: ca-cert readOnly: true volumes: - name: socket-dir hostPath: path: /var/lib/csi/sockets/pluginproxy/ type: DirectoryOrCreate - name: secret-cinderplugin secret: secretName: cloud-config - name: ca-cert secret: secretName: openstack-ca-cert Create cinder-csi-nodeplugin.yaml and apply it to create csi node.
kind: DaemonSet apiVersion: apps/v1 metadata: name: csi-cinder-nodeplugin namespace: kube-system spec: selector: matchLabels: app: csi-cinder-nodeplugin template: metadata: labels: app: csi-cinder-nodeplugin spec: serviceAccount: csi-cinder-node-sa hostNetwork: true containers: - name: node-driver-registrar image: quay.io/k8scsi/csi-node-driver-registrar:v1.1.0 args: - "--v=5" - "--csi-address=$(ADDRESS)" - "--kubelet-registration-path=$(DRIVER_REG_SOCK_PATH)" lifecycle: preStop: exec: command: ["/bin/sh", "-c", "rm -rf /registration/cinder.csi.openstack.org /registration/cinder.csi.openstack.org-reg.sock"] env: - name: ADDRESS value: /csi/csi.sock - name: DRIVER_REG_SOCK_PATH value: /var/lib/kubelet/plugins/cinder.csi.openstack.org/csi.sock - name: KUBE_NODE_NAME valueFrom: fieldRef: fieldPath: spec.nodeName imagePullPolicy: "IfNotPresent" volumeMounts: - name: socket-dir mountPath: /csi - name: registration-dir mountPath: /registration - name: cinder-csi-plugin securityContext: privileged: true capabilities: add: ["SYS_ADMIN"] allowPrivilegeEscalation: true image: docker.io/k8scloudprovider/cinder-csi-plugin:v1.15.0 args : - /bin/cinder-csi-plugin - "--nodeid=$(NODE_ID)" - "--endpoint=$(CSI_ENDPOINT)" - "--cloud-config=$(CLOUD_CONFIG)" env: - name: NODE_ID valueFrom: fieldRef: fieldPath: spec.nodeName - name: CSI_ENDPOINT value: unix://csi/csi.sock - name: CLOUD_CONFIG value: /etc/config/cloud.conf imagePullPolicy: "IfNotPresent" volumeMounts: - name: socket-dir mountPath: /csi - name: pods-mount-dir mountPath: /var/lib/kubelet/pods mountPropagation: "Bidirectional" - name: kubelet-dir mountPath: /var/lib/kubelet mountPropagation: "Bidirectional" - name: pods-cloud-data mountPath: /var/lib/cloud/data readOnly: true - name: pods-probe-dir mountPath: /dev mountPropagation: "HostToContainer" - name: secret-cinderplugin mountPath: /etc/config readOnly: true - mountPath: /etc/kubernetes name: ca-cert readOnly: true volumes: - name: socket-dir hostPath: path: /var/lib/kubelet/plugins/cinder.csi.openstack.org type: DirectoryOrCreate - name: registration-dir hostPath: path: /var/lib/kubelet/plugins_registry/ type: Directory - name: kubelet-dir hostPath: path: /var/lib/kubelet type: Directory - name: pods-mount-dir hostPath: path: /var/lib/kubelet/pods type: Directory - name: pods-cloud-data hostPath: path: /var/lib/cloud/data type: Directory - name: pods-probe-dir hostPath: path: /dev type: Directory - name: secret-cinderplugin secret: secretName: cloud-config - name: ca-cert secret: secretName: openstack-ca-cert When they are both running, create a storage class for Cinder.
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: csi-sc-cinderplugin provisioner: csi-cinderplugin Then we can create a PVC with this class.
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: myvol spec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi storageClassName: csi-sc-cinderplugin When the PVC is created, a Cinder volume is created correspondingly.
# kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE myvol Bound pvc-14b8bc68-6c4c-4dc6-ad79-4cb29a81faad 1Gi RWO csi-sc-cinderplugin 3s In OpenStack the volume name will match the Kubernetes persistent volume generated name. In this example it would be: pvc-14b8bc68-6c4c-4dc6-ad79-4cb29a81faad
Now we can create a pod with the PVC.
apiVersion: v1 kind: Pod metadata: name: web spec: containers: - name: web image: nginx ports: - name: web containerPort: 80 hostPort: 8081 protocol: TCP volumeMounts: - mountPath: "/usr/share/nginx/html" name: mypd volumes: - name: mypd persistentVolumeClaim: claimName: myvol When the pod is running, the volume will be attached to the pod. If we go back to OpenStack, we can see the Cinder volume is mounted to the worker node where the pod is running on.
# openstack volume show 6b5f3296-b0eb-40cd-bd4f-2067a0d6287f +--------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Field | Value | +--------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | attachments | [{u'server_id': u'1c5e1439-edfa-40ed-91fe-2a0e12bc7eb4', u'attachment_id': u'11a15b30-5c24-41d4-86d9-d92823983a32', u'attached_at': u'2019-07-24T05:02:34.000000', u'host_name': u'compute-6', u'volume_id': u'6b5f3296-b0eb-40cd-bd4f-2067a0d6287f', u'device': u'/dev/vdb', u'id': u'6b5f3296-b0eb-40cd-bd4f-2067a0d6287f'}] | | availability_zone | nova | | bootable | false | | consistencygroup_id | None | | created_at | 2019-07-24T05:02:18.000000 | | description | Created by OpenStack Cinder CSI driver | | encrypted | False | | id | 6b5f3296-b0eb-40cd-bd4f-2067a0d6287f | | migration_status | None | | multiattach | False | | name | pvc-14b8bc68-6c4c-4dc6-ad79-4cb29a81faad | | os-vol-host-attr:host | rbd:volumes@rbd#rbd | | os-vol-mig-status-attr:migstat | None | | os-vol-mig-status-attr:name_id | None | | os-vol-tenant-attr:tenant_id | 14ba698c0aec4fd6b7dc8c310f664009 | | properties | attached_mode='rw', cinder.csi.openstack.org/cluster='kubernetes' | | replication_status | None | | size | 1 | | snapshot_id | None | | source_volid | None | | status | in-use | | type | rbd | | updated_at | 2019-07-24T05:02:35.000000 | | user_id | 5f6a7a06f4e3456c890130d56babf591 | +--------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ Summary
In this walk-through, we deployed a Kubernetes cluster on OpenStack VMs and integrated it with OpenStack using an external OpenStack cloud provider. Then on this Kubernetes cluster we deployed Cinder CSI plugin which can create Cinder volumes and expose them in Kubernetes as persistent volumes.