养浩然之气,做博学之人
部署高可用 kube-scheduler 集群,该集群包含 3 个节点,启动后将通过竞争选举机制产生一个 leader 节点,其它节点为阻塞状态。当 leader 节点不可用后,剩余节点将再次进行选举产生新的 leader 节点,从而保证服务的可用性。
为保证通信安全,本文档先生成 x509 证书和私钥,kube-scheduler 在如下两种情况下使用该证书:
(1)与 kube-apiserver 的安全端口通信;
(2)在安全端口(https,10251) 输出 prometheus 格式的 metrics;
下载最新版本的二进制文件、安装和配置 flanneld (已完成)
创建证书签名请求:
cat > kube-scheduler-csr.json << EOF{ "CN": "system:kube-scheduler", "hosts": [ "127.0.0.1", "192.168.1.110", "192.168.1.111", "192.168.1.112" ], "key": { "algo": "rsa", "size": 2048 }, "names": [ { "C": "CN", "ST": "BeiJing", "L": "BeiJing", "O": "system:kube-scheduler", "OU": "xiaowangyun" } ] } EOF
#hosts 列表包含所有 kube-scheduler 节点 IP;
#CN 为 system:kube-scheduler、O 为 system:kube-scheduler,kubernetes 内置的 ClusterRoleBindings system:kube-scheduler 将赋予 kube-scheduler 工作所需的权限。
生成证书和私钥:
cfssl gencert -ca=/etc/kubernetes/cert/ca.pem -ca-key=/etc/kubernetes/cert/ca-key.pem -config=/etc/kubernetes/cert/ca-config.json -profile=kubernetes kube-scheduler-csr.json | cfssljson -bare kube-scheduler
kubeconfig 文件包含访问 apiserver 的所有信息,如 apiserver 地址、CA 证书和自身使用的证书;
source /opt/k8s/bin/environment.sh kubectl config set-cluster kubernetes --certificate-authority=/etc/kubernetes/cert/ca.pem --embed-certs=true --server=${KUBE_APISERVER} --kubeconfig=kube-scheduler.kubeconfig kubectl config set-credentials system:kube-scheduler --client-certificate=kube-scheduler.pem --client-key=kube-scheduler-key.pem --embed-certs=true --kubeconfig=kube-scheduler.kubeconfig kubectl config set-context system:kube-scheduler --cluster=kubernetes --user=system:kube-scheduler --kubeconfig=kube-scheduler.kubeconfig kubectl config use-context system:kube-scheduler --kubeconfig=kube-scheduler.kubeconfig
上一步创建的证书、私钥以及 kube-apiserver 地址被写入到 kubeconfig 文件中;
分发 kubeconfig 到所有 master 节点:
for node_ip in ${MASTER_IPS[@]} do echo ">>> ${node_ip}" scp kube-scheduler.kubeconfig k8s@${node_ip}:/etc/kubernetes/ done
cat > kube-scheduler.service <<EOF [Unit] Description=Kubernetes Scheduler Documentation=https://github.com/GoogleCloudPlatform/kubernetes [Service] ExecStart=/opt/k8s/bin/kube-scheduler \ --address=127.0.0.1 \ --kubeconfig=/etc/kubernetes/kube-scheduler.kubeconfig \ --leader-elect=true \ --alsologtostderr=true \ --logtostderr=false \ --log-dir=/var/log/kubernetes \ --v=2 Restart=on-failure RestartSec=5 User=k8s [Install] WantedBy=multi-user.target EOF
#--address:在 127.0.0.1:10251 端口接收 http /metrics 请求;kube-scheduler 目前还不支持接收 https 请求;
#--kubeconfig:指定 kubeconfig 文件路径,kube-scheduler 使用它连接和验证 kube-apiserver;
#--leader-elect=true:集群运行模式,启用选举功能;被选为 leader 的节点负责处理工作,其它节点为阻塞状态;
#User=k8s:使用 k8s 账户运行;
分发 systemd unit 文件到所有 master 节点:
source /opt/k8s/bin/environment.sh for node_ip in ${MASTER_IPS[@]} do echo ">>> ${node_ip}" scp kube-scheduler.service root@${node_ip}:/etc/systemd/system/ done
source /opt/k8s/bin/environment.sh for node_ip in ${MASTER_IPS[@]} do echo ">>> ${node_ip}" ssh root@${node_ip} "mkdir -p /var/log/kubernetes && chown -R k8s /var/log/kubernetes" ssh root@${node_ip} "systemctl daemon-reload && systemctl enable kube-scheduler && systemctl restart kube-scheduler" done
#必须先创建日志目录;
source /opt/k8s/bin/environment.sh for node_ip in ${MASTER_IPS[@]} do echo ">>> ${node_ip}" ssh k8s@${node_ip} "systemctl status kube-scheduler|grep Active" done
#确保状态为 active (running),否则查看日志,确认原因:journalctl -u kube-scheduler
注意:以下命令在 kube-scheduler 节点上执行。
kube-scheduler 监听 10251 端口,接收 http 请求:
sudo netstat -lnpt|grep kube-sche #tcp 0 0 127.0.0.1:10251 0.0.0.0:* LISTEN 14419/kube-schedule
curl -s http://127.0.0.1:10251/metrics |head
输出:
# HELP apiserver_audit_event_total Counter of audit events generated and sent to the audit backend.
# TYPE apiserver_audit_event_total counter
apiserver_audit_event_total 0
# HELP go_gc_duration_seconds A summary of the GC invocation durations.
# TYPE go_gc_duration_seconds summary
go_gc_duration_seconds{quantile="0"} 1.9806e-05
go_gc_duration_seconds{quantile="0.25"} 2.4767e-05
go_gc_duration_seconds{quantile="0.5"} 2.6948e-05
go_gc_duration_seconds{quantile="0.75"} 3.2249e-05
go_gc_duration_seconds{quantile="1"} 8.3068e-05
随便找一个或两个 master 节点,停掉 kube-scheduler 服务,看其它节点是否获取了 leader 权限(systemd 日志)。
kubectl get endpoints kube-scheduler --namespace=kube-system -o yaml
当前leader 为docker110:"holderIdentity":"docker110_19f089ec-9df0-11e8-8060-000c2931fef9",
systemctl stop kube-scheduler kubectl get endpoints kube-scheduler --namespace=kube-system -o yaml
leader变成docker111:{"holderIdentity":"docker111_1a849a1a-9df0-11e8-9e7c-000c29b0eb92"
参考:
https://www.kubernetes.org.cn/3063.html
https://www.kubernetes.org.cn/3096.html
https://github.com/opsnull/follow-me-install-kubernetes-cluster
http://www.imooc.com/article/23355
https://www.docker.com/
编辑:孙小北
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