• --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：

cat > magic.sh << "EOF"
#!/bin/bash

source /opt/k8s/bin/environment.sh

for node_ip in ${NODE_IPS[@]}
do
    echo ">>> ${node_ip}" 
    scp kube-scheduler.service root@${node_ip}:/etc/systemd/system/
done
EOF

4，启动 kube-scheduler 服务

cat > magic.sh << "EOF"
#!/bin/bash

source /opt/k8s/bin/environment.sh

for node_ip in ${NODE_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 start kube-scheduler"
done
EOF

5，检查服务运行状态

cat > magic.sh << "EOF"
#!/bin/bash

source /opt/k8s/bin/environment.sh

for node_ip in ${NODE_IPS[@]}
do
    echo ">>> ${node_ip}" 
    ssh k8s@${node_ip} "systemctl status kube-scheduler|grep Active"
done
EOF

如果看到如下输出：

$bash magic.sh
>>> 192.168.106.3
   Active: active (running) since Fri 2018-11-23 18:31:30 CST; 6h ago
>>> 192.168.106.4
   Active: active (running) since Fri 2018-11-23 18:29:32 CST; 6h ago
>>> 192.168.106.5
   Active: active (running) since Fri 2018-11-23 18:29:32 CST; 6h ago

则正常，如果失败，看日志：

journalctl -xu kube-scheduler

5，查看输出的 metric

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      15377/kube-schedule

$curl -s http://127.0.0.1:10251/metrics |head
# 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"} 6.3423e-05
go_gc_duration_seconds{quantile="0.25"} 0.000120079
go_gc_duration_seconds{quantile="0.5"} 0.000146495
go_gc_duration_seconds{quantile="0.75"} 0.000174475
go_gc_duration_seconds{quantile="1"} 0.001807813

6，查看当前的 leader

$kubectl get endpoints kube-scheduler --namespace=kube-system  -o yaml
apiVersion: v1
kind: Endpoints
metadata:
  annotations:
    control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"kube-node2_aa57b017-ef0a-11e8-aaf2-5254001a681e","leaseDurationSeconds":15,"acquireTime":"2018-11-23T10:31:09Z","renewTime":"2018-11-23T17:05:31Z","leaderTransitions":1}'
  creationTimestamp: 2018-11-23T10:29:32Z
  name: kube-scheduler
  namespace: kube-system
  resourceVersion: "30835"
  selfLink: /api/v1/namespaces/kube-system/endpoints/kube-scheduler
  uid: aabb2233-ef0a-11e8-9670-525400c7ba97

可见，当前的 leader 为 kube-node2 节点。

7，测试 kube-scheduler 集群的高可用

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）。

现在就去停掉kube-node2上的kube-scheduler 服务。

$systemctl stop kube-scheduler

$systemctl status kube-scheduler | grep Active
   Active: inactive (dead) since Sat 2018-11-24 01:06:40 CST; 14s ago

然后再来查看一下现在的leader是谁：

$kubectl get endpoints kube-scheduler --namespace=kube-system  -o yaml
apiVersion: v1
kind: Endpoints
metadata:
  annotations:
    control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"kube-node3_aa9017f9-ef0a-11e8-b73d-525400b42484","leaseDurationSeconds":15,"acquireTime":"2018-11-23T17:06:57Z","renewTime":"2018-11-23T17:07:31Z","leaderTransitions":2}'
  creationTimestamp: 2018-11-23T10:29:32Z
  name: kube-scheduler
  namespace: kube-system
  resourceVersion: "30984"
  selfLink: /api/v1/namespaces/kube-system/endpoints/kube-scheduler
  uid: aabb2233-ef0a-11e8-9670-525400c7ba97

可以看到，已经漂移到了kube-node3上去了。