PXC介绍
全称percona-xtradb-cluster，提供了MySQL高可用的一种实现方法。PXC集群以节点组成（推荐至少3节点，便于故障恢复），每个节点都是基于常规的 MySQL Server，意味着你可以从集群中分离出某节点单独使用，集群中每个节点都包含完整的数据。
PXC特性
- 同步复制
- 支持多主复制
- 支持并行复制
- 作为高可用方案，实施相对简单
架构图如下所示
部署PXC集群到kubernetes
1、下载部署文件
git clone -b v1.5.0 https://github.com/percona/percona-xtradb-cluster-operator
2、创建CRD
[root@k8s-master001 deploy]# kubectl apply -f crd.yaml
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/perconaxtradbclusters.pxc.percona.com created
customresourcedefinition.apiextensions.k8s.io/perconaxtradbclusterbackups.pxc.percona.com created
customresourcedefinition.apiextensions.k8s.io/perconaxtradbclusterrestores.pxc.percona.com created
customresourcedefinition.apiextensions.k8s.io/perconaxtradbbackups.pxc.percona.com created
3、创建namespace
[root@k8s-master001 deploy]# kubectl create namespace pxc
namespace/pxc created
[root@k8s-master001 deploy]# kubectl config set-context $(kubectl config current-context) --namespace=pxc
Context "kubernetes-admin@kubernetes" modified.
4、创建RBAC
[root@k8s-master001 deploy]# kubectl apply -f rbac.yaml
Warning: rbac.authorization.k8s.io/v1beta1 Role is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 Role
role.rbac.authorization.k8s.io/percona-xtradb-cluster-operator created
serviceaccount/percona-xtradb-cluster-operator created
serviceaccount/percona-xtradb-cluster-operator-workload created
Warning: rbac.authorization.k8s.io/v1beta1 RoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 RoleBinding
rolebinding.rbac.authorization.k8s.io/service-account-percona-xtradb-cluster-operator created
5、创建operator
[root@k8s-master001 deploy]# kubectl apply -f operator.yaml
deployment.apps/percona-xtradb-cluster-operator created
[root@k8s-master001 deploy]# kubectl get po -n pxc
NAME READY STATUS RESTARTS AGE
percona-xtradb-cluster-operator-54d9b7c858-hkmsp 1/1 Running 0 2m19s
6、创建secrets
创建root密码，并修改secrets.yaml中的root字段为新生成的密码
[root@k8s-master001 deploy]# echo -n 'pxcadmin' | base64
cHhjYWRtaW4=
[root@k8s-master001 deploy]# kubectl apply -f secrets.yaml
secret/my-cluster-secrets created
7、创建Percona XtraDB Cluster
修改配置
updateStrategy: OnDelete
指定存储类和存储大小
rook-ceph是k8s的存储类，可以通过kubectl get sc获取
persistentVolumeClaim:
storageClassName: rook-ceph
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 6Gi
执行部署
[root@k8s-master001 deploy]# kubectl apply -f cr.yaml
perconaxtradbcluster.pxc.percona.com/cluster1 created
[root@k8s-master001 deploy]# kubectl get po -n pxc
NAME READY STATUS RESTARTS AGE
cluster1-haproxy-0 2/2 Running 0 17m
cluster1-haproxy-1 2/2 Running 0 15m
cluster1-haproxy-2 2/2 Running 0 13m
cluster1-pxc-0 1/1 Running 0 17m
cluster1-pxc-1 1/1 Running 0 6m28s
cluster1-pxc-2 1/1 Running 0 3m33s
8、验证：
运行一个percona-client
kubectl run -i --rm --tty percona-client --image=percona:5.7 --restart=Never -- bash -il
查看3306代理，这里官方用的是haproxy
sh-4.2$ env|grep 3306
CLUSTER1_HAPROXY_SERVICE_PORT=3306
CLUSTER1_HAPROXY_REPLICAS_PORT_3306_TCP_PORT=3306
CLUSTER1_HAPROXY_PORT=tcp://10.106.76.114:3306
连接数据库，查看集群信息,wsrep_cluster_size=3,表示现在集群有3个节点 ，更多信息自己查看输出信息
sh-4.2$ mysql -h10.106.76.114 -uroot -ppxcadmin
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql>
mysql> show status like 'wsrep%';
+----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value |
+----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| wsrep_local_state_uuid | 703296d1-f72b-11ea-93ec-5267957b341b |
| wsrep_cluster_capabilities | |
| wsrep_cluster_conf_id | 5 |
| wsrep_cluster_size | 3 |
| wsrep_cluster_state_uuid | 703296d1-f72b-11ea-93ec-5267957b341b |
| wsrep_cluster_status | Primary |
| wsrep_connected | ON |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_index | 2 |
| wsrep_provider_capabilities | :MULTI_MASTER:CERTIFICATION:PARALLEL_APPLYING:TRX_REPLAY:ISOLATION:PAUSE:CAUSAL_READS:INCREMENTAL_WRITESET:UNORDERED:PREORDERED:STREAMING:NBO: |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <info@codership.com> |
| wsrep_provider_version | 4.3(r752664d) |
| wsrep_ready | ON |
| wsrep_thread_count | 3 |
+----------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
75 rows in set (0.01 sec)
9、说明
kubectl get po -n pxc
NAME READY STATUS RESTARTS AGE
cluster1-haproxy-0 2/2 Running 0 39m
cluster1-haproxy-1 2/2 Running 0 36m
cluster1-haproxy-2 2/2 Running 0 35m
cluster1-pxc-0 1/1 Running 1 39m
cluster1-pxc-1 1/1 Running 0 28m
cluster1-pxc-2 1/1 Running 0 25m
percona-client 1/1 Running 0 16m
percona-xtradb-cluster-operator-54d9b7c858-hkmsp 1/1 Running 0 65m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/cluster1-haproxy ClusterIP 10.106.76.114 <none> 3306/TCP,3309/TCP 43m
service/cluster1-haproxy-replicas ClusterIP 10.104.239.57 <none> 3306/TCP 43m
service/cluster1-pxc ClusterIP None <none> 3306/TCP 43m
service/cluster1-pxc-unready ClusterIP None <none> 3306/TCP 43m
- 从以上输出可以看到，运行了三个pxc节点，这里可以视为物理机三个mysql节点，除此之外，还有三个haproxy。说明使用haproxy来为pxc集群提供代理服务，进入到cluster1-haproxy-0 可以看到如下信息
server cluster1-pxc-0 cluster1-pxc-0.cluster1-pxc.pxc.svc.cluster.local:3306 check inter 10000 rise 1 fall 2 weight 1
server cluster1-pxc-1 cluster1-pxc-1.cluster1-pxc.pxc.svc.cluster.local:3306 check inter 10000 rise 1 fall 2 weight 1
server cluster1-pxc-2 cluster1-pxc-2.cluster1-pxc.pxc.svc.cluster.local:3306 check inter 10000 rise 1 fall 2 weight 1
-
再来看service，创建了cluster1-haproxy，如果在kubernetes集群内部，可以直接通过CLUSTER-IP+PORT访问到数据库
-
如果想在集群外部访问到数据库，可以使用前文介绍的Ingress来暴露TCP服务，如果测试，也可使创建一个NodePort来暴露服。务下一篇我们就来就使用前文介绍过的Ingress来把mysql的服务暴露出去，顺便介绍Nginx-Ingress。
