calico 配置 BGP Route Reflectors
Calico作为k8s的一个流行网络插件，它依赖BGP路由协议实现集群节点上的POD路由互通；而路由互通的前提是节点间建立 BGP Peer 连接。BGP 路由反射器（Route Reflectors，简称 RR）可以简化集群BGP Peer的连接方式，它是解决BGP扩展性问题的有效方式；具体来说：
- 没有 RR 时，所有节点之间需要两两建立连接（IBGP全互联），节点数量增加将导致连接数剧增、资源占用剧增
- 引入 RR 后，其他 BGP 路由器只需要与它建立连接并交换路由信息，节点数量增加连接数只是线性增加，节省系统资源
calico-node 版本 v3.3 开始支持内建路由反射器，非常方便，因此使用 calico 作为网络插件可以支持大规模节点数的K8S集群。
- 建议集群节点数大于50时，应用BGP Route Reflectors 特性
前提条件
k8s 集群使用calico网络插件部署成功。本实验环境为按照kubeasz安装的2主2从集群，calico 版本 v3.19.4。
$ kubectl get node
NAME STATUS ROLES AGE VERSION
192.168.1.1 Ready,SchedulingDisabled master 178m v1.13.1
192.168.1.2 Ready,SchedulingDisabled master 178m v1.13.1
192.168.1.3 Ready node 178m v1.13.1
192.168.1.4 Ready node 178m v1.13.1
$ kubectl get pod -n kube-system -o wide | grep calico
calico-kube-controllers-77487546bd-jqrlc 1/1 Running 0 179m 192.168.1.3 192.168.1.3 <none> <none>
calico-node-67t5m 2/2 Running 0 179m 192.168.1.1 192.168.1.1 <none> <none>
calico-node-drmhq 2/2 Running 0 179m 192.168.1.2 192.168.1.2 <none> <none>
calico-node-rjtkv 2/2 Running 0 179m 192.168.1.4 192.168.1.4 <none> <none>
calico-node-xtspl 2/2 Running 0 179m 192.168.1.3 192.168.1.3 <none> <none>
查看当前集群中BGP连接情况：可以看到集群中4个节点两两建立了 BGP 连接
$ dk ansible -i /etc/kubeasz/clusters/xxx/hosts all -m shell -a '/opt/kube/bin/calicoctl node status'
192.168.1.3 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-------------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-------------------+-------+----------+-------------+
| 192.168.1.1 | node-to-node mesh | up | 03:08:20 | Established |
| 192.168.1.2 | node-to-node mesh | up | 03:08:18 | Established |
| 192.168.1.4 | node-to-node mesh | up | 03:08:19 | Established |
+--------------+-------------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.2 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-------------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-------------------+-------+----------+-------------+
| 192.168.1.4 | node-to-node mesh | up | 03:08:17 | Established |
| 192.168.1.3 | node-to-node mesh | up | 03:08:18 | Established |
| 192.168.1.1 | node-to-node mesh | up | 03:08:20 | Established |
+--------------+-------------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.1 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-------------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-------------------+-------+----------+-------------+
| 192.168.1.2 | node-to-node mesh | up | 03:08:21 | Established |
| 192.168.1.3 | node-to-node mesh | up | 03:08:21 | Established |
| 192.168.1.4 | node-to-node mesh | up | 03:08:21 | Established |
+--------------+-------------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.4 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-------------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-------------------+-------+----------+-------------+
| 192.168.1.2 | node-to-node mesh | up | 03:08:17 | Established |
| 192.168.1.3 | node-to-node mesh | up | 03:08:19 | Established |
| 192.168.1.1 | node-to-node mesh | up | 03:08:20 | Established |
+--------------+-------------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
kubeasz 自动安装启用 route reflector
- 修改
/etc/kubeasz/clusters/xxx/config.yml文件，设置配置项CALICO_RR_ENABLED: true - 重新执行网络安装
dk ezctl setup xxx 07
执行完成，检查bgp连接验证即可。
附：手动安装route reflector 过程讲解
- 选择并配置 Route Reflector 节点
首先查看当前集群中的节点：
$ calicoctl get node -o wide
NAME ASN IPV4 IPV6
k8s401 (64512) 192.168.1.1/24
k8s402 (64512) 192.168.1.2/24
k8s403 (64512) 192.168.1.3/24
k8s404 (64512) 192.168.1.4/24
可以在集群中选择1个或多个节点作为 rr 节点，这里先选择节点：k8s401
#配置routeReflectorClusterID
calicoctl patch node k8s401 -p '{"spec": {"bgp": {"routeReflectorClusterID": "244.0.0.1"}}}'
#配置node label
calicoctl patch node k8s401 -p '{"metadata": {"labels": {"route-reflector": "true"}}}'
- 配置 BGP node 与 Route Reflector 的连接建立规则
$ cat << EOF | calicoctl create -f -
kind: BGPPeer
apiVersion: projectcalico.org/v3
metadata:
name: peer-with-route-reflectors
spec:
nodeSelector: all()
peerSelector: route-reflector == 'true'
EOF
- 配置全局禁用全连接（BGP full mesh）
$ cat << EOF | calicoctl create -f -
apiVersion: projectcalico.org/v3
kind: BGPConfiguration
metadata:
name: default
spec:
logSeverityScreen: Info
nodeToNodeMeshEnabled: false
asNumber: 64512
EOF
- 验证增加 rr 之后的bgp 连接情况
$ dk ansible -i /etc/kubeasz/clusters/xxx/hosts all -m shell -a '/opt/kube/bin/calicoctl node status'
192.168.1.4 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-----------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-----------+-------+----------+-------------+
| 192.168.1.1 | node specific | up | 11:02:55 | Established |
+--------------+-----------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.3 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-----------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-----------+-------+----------+-------------+
| 192.168.1.1 | node specific | up | 11:02:55 | Established |
+--------------+-----------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.1 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+---------------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+---------------+-------+----------+-------------+
| 192.168.1.2 | node specific | up | 11:02:55 | Established |
| 192.168.1.3 | node specific | up | 11:02:55 | Established |
| 192.168.1.4 | node specific | up | 11:02:55 | Established |
+--------------+---------------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
192.168.1.2 | SUCCESS | rc=0 >>
Calico process is running.
IPv4 BGP status
+--------------+-----------+-------+----------+-------------+
| PEER ADDRESS | PEER TYPE | STATE | SINCE | INFO |
+--------------+-----------+-------+----------+-------------+
| 192.168.1.1 | node specific | up | 11:02:55 | Established |
+--------------+-----------+-------+----------+-------------+
IPv6 BGP status
No IPv6 peers found.
可以看到所有其他节点都与所选rr节点建立bgp连接。
- 再增加一个 rr 节点(略)
步骤同上，添加成功后可以看到所有其他节点都与两个rr节点建立bgp连接，两个rr节点之间也建立bgp连接。对于节点数较多的K8S集群建议配置2-3个 RR 节点。