PXC介紹
全稱percona-xtradb-cluster，提供了MySQL高可用的一種實現方法。PXC集群以節點組成（推薦至少3節點，便於故障恢復），每個節點都是基於常規的 MySQL Server，意味着你可以從集群中分離出某節點單獨使用，集群中每個節點都包含完整的數據。
PXC特性
- 同步復制
- 支持多主復制
- 支持並行復制
- 作為高可用方案，實施相對簡單
架構圖如下所示
部署PXC集群到kubernetes
1、下載部署文件
git clone -b v1.5.0 https://github.com/percona/percona-xtradb-cluster-operator
2、創建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、創建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、創建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、創建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、創建secrets
創建root密碼，並修改secrets.yaml中的root字段為新生成的密碼
[root@k8s-master001 deploy]# echo -n 'pxcadmin' | base64
cHhjYWRtaW4=
[root@k8s-master001 deploy]# kubectl apply -f secrets.yaml
secret/my-cluster-secrets created
7、創建Percona XtraDB Cluster
修改配置
updateStrategy: OnDelete
指定存儲類和存儲大小
rook-ceph是k8s的存儲類，可以通過kubectl get sc獲取
persistentVolumeClaim:
storageClassName: rook-ceph
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 6Gi
執行部署
[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、驗證：
運行一個percona-client
kubectl run -i --rm --tty percona-client --image=percona:5.7 --restart=Never -- bash -il
查看3306代理，這里官方用的是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
連接數據庫，查看集群信息,wsrep_cluster_size=3,表示現在集群有3個節點 ，更多信息自己查看輸出信息
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、說明
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
- 從以上輸出可以看到，運行了三個pxc節點，這里可以視為物理機三個mysql節點，除此之外，還有三個haproxy。說明使用haproxy來為pxc集群提供代理服務，進入到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
-
再來看service，創建了cluster1-haproxy，如果在kubernetes集群內部，可以直接通過CLUSTER-IP+PORT訪問到數據庫
-
如果想在集群外部訪問到數據庫，可以使用前文介紹的Ingress來暴露TCP服務，如果測試，也可使創建一個NodePort來暴露服。務下一篇我們就來就使用前文介紹過的Ingress來把mysql的服務暴露出去，順便介紹Nginx-Ingress。
