# 容器化安装
本文详细介绍如何在Docker中部署GreatSQL，并且构建一个MGR集群。
# 1. 安装Docker
直接用yum/dnf安装docker，非常省事
$ yum install -y docker
之后启动 docker 服务，并设置开机自启动
$ systemctl enable docker
$ systemctl start docker
# 2. 拉取GreatSQL镜像，并创建容器
# 2.1 拉取镜像
拉取GreatSQL官方镜像
$ docker pull greatsql/greatsql
docker pull greatsql/greatsql
Using default tag: latest
Trying to pull repository docker.io/greatsql/greatsql ...
latest: Pulling from docker.io/greatsql/greatsql
...
Digest: sha256:03969daaaaaeb0f51dde0c9e92ef327302607cdde3afbe5c2b071098000c52c1
Status: Downloaded newer image for greatsql/greatsql:latest
docker.io/greatsql/greatsql:latest
检查是否成功
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/greatsql/greatsql latest a930afc72d88 8 weeks ago 923 MB
# 2.2 创建新容器
之后，就可以直接创建一个新的容器了，先用常规方式
$ docker run -d --name greatsql --hostname=greatsql -e MYSQL_ALLOW_EMPTY_PASSWORD=1 greatsql/greatsql
容器的命名和容器内主机名均为greatsql。
确认容器状态：
$ docker ps -a | grep greatsql
...
4f351e22cea9 greatsql/greatsql "/docker-entrypoint.…" About a minute ago Up About a minute 3306/tcp, 33060-33061/tcp greatsql
...
看到容器状态是Up的，表示已正常启动了。
# 2.3 容器管理
进入容器查看
$ docker exec -it greatsql /bin/bash
[root@greatsql /]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 8.0.25-16 GreatSQL (GPL), Release 16, Revision 8bb0e5af297
...
Server version: 8.0.25-16 GreatSQL (GPL), Release 16, Revision 8bb0e5af297
...
Threads: 2 Questions: 18 Slow queries: 0 Opens: 119 Flush tables: 3 Open tables: 36 Queries per second avg: 0.243
看到容器已经完成初始化，并且可以直接无密码登入。
# 3. 利用Docker-compose创建Docker容器并构建MGR集群
手工管理Docker比较麻烦，建议采用 docker-compose ，它可以更方便的管理docker容器。
先用yum安装docker-compose，并确认版本号
$ yum install -y docker-compose
$ docker-compose --version
docker-compose version 1.29.2, build 5becea4c
编辑一个yaml文件，准备部署包含仲裁节点的三节点MGR集群：
$ mkdir -p /data/docker-compose
$ cat /data/docker-compose/mgr-3nodes.yml
version: '2'
services:
mgr2:
image: greatsql/greatsql #指定镜像
container_name: mgr2 #设定容器名字
hostname: mgr2 #设定容器中的主机名
networks: #指定容器使用哪个专用网络
mgr_net:
ipv4_address: 172.18.0.2 #设置容器使用固定IP地址，避免重启后IP变化
restart: unless-stopped #设定重启策略
environment: #设置多个环境变量
TZ: Asia/Shanghai #时区
MYSQL_ALLOW_EMPTY_PASSWORD: 1 #允许root账户空密码
MYSQL_INIT_MGR: 1 #初始化MGR集群
MYSQL_MGR_LOCAL: '172.18.0.2:33061' #当前MGR节点的local_address
MYSQL_MGR_SEEDS: '172.18.0.2:33061,172.18.0.3:33061,172.18.0.4:33061' #MGR集群seeds
MYSQL_MGR_START_AS_PRIMARY: 1 #指定当前MGR节点为Primary角色
MYSQL_MGR_ARBITRATOR: 0
#MYSQL_MGR_VIEWID: "aaaaaaaa-bbbb-bbbb-aaaa-aaaaaaaaaaa1"
mgr3:
image: greatsql/greatsql
container_name: mgr3
hostname: mgr3
networks:
mgr_net:
ipv4_address: 172.18.0.3
restart: unless-stopped
depends_on:
- "mgr2"
environment:
TZ: Asia/Shanghai
MYSQL_ALLOW_EMPTY_PASSWORD: 1
MYSQL_INIT_MGR: 1
MYSQL_MGR_LOCAL: '172.18.0.3:33061'
MYSQL_MGR_SEEDS: '172.18.0.2:33061,172.18.0.3:33061,172.18.0.4:33061'
MYSQL_MGR_START_AS_PRIMARY: 0
MYSQL_MGR_ARBITRATOR: 0 #既非Primary，也非Arbitrator，那么就是Secondary角色了
#MYSQL_MGR_VIEWID: "aaaaaaaa-bbbb-bbbb-aaaa-aaaaaaaaaaa1"
mgr4:
image: greatsql/greatsql
container_name: mgr4
hostname: mgr4
networks:
mgr_net:
ipv4_address: 172.18.0.4
restart: unless-stopped
depends_on:
- "mgr3"
environment:
TZ: Asia/Shanghai
MYSQL_ALLOW_EMPTY_PASSWORD: 1
MYSQL_INIT_MGR: 1
MYSQL_MGR_LOCAL: '172.18.0.4:33061'
MYSQL_MGR_SEEDS: '172.18.0.2:33061,172.18.0.3:33061,172.18.0.4:33061'
MYSQL_MGR_START_AS_PRIMARY: 0
MYSQL_MGR_ARBITRATOR: 1 #指定当前MGR节点为Arbitrator角色，此时不能同时指定其为Primary/Secondary角色
#MYSQL_MGR_VIEWID: "aaaaaaaa-bbbb-bbbb-aaaa-aaaaaaaaaaa1"
networks:
mgr_net: #创建独立MGR专属网络
ipam:
config:
- subnet: 172.18.0.0/24
关于GreatSQL容器启动选项说明，详见GreatSQL For Docker文档 (opens new window)。
如果不想要仲裁节点，则可以修改最后一个节点的属性 MYSQL_MGR_ARBITRATOR: 0 就行了。
另外，利用 docker-compose 方式暂时无法构建多主模式的MGR集群，需要手动部署。
启动三个实例：
$ docker-compose -f /data/docker-compose/mgr-3nodes.yml up -d
Creating network "docker-compose_mgr_net" with the default driver
Creating mgr2 ... done
Creating mgr3 ... done
Creating mgr4 ... done
查看运行状态：
$ docker-compose -f /data/docker-compose/mgr-3nodes.yml up -d
Name Command State Ports
----------------------------------------------------------------------------
mgr2 /docker-entrypoint.sh mysqld Up 3306/tcp, 33060/tcp, 33061/tcp
mgr3 /docker-entrypoint.sh mysqld Up 3306/tcp, 33060/tcp, 33061/tcp
mgr4 /docker-entrypoint.sh mysqld Up 3306/tcp, 33060/tcp, 33061/tcp
容器刚创建完还需要过一小段时间才能完成GreatSQL的初始化以及MGR集群自动构建，视服务器性能不同而定，一般需要30秒至四分钟左右。
进入被选为PRIMARY节点的容器mgr2，查看MGR集群状态：
$ docker exec -it mgr2 bash
[root@mgr2 /]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 30
Server version: 8.0.25-16 GreatSQL (GPL), Release 16, Revision 8bb0e5af297
...
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
(Tue Jul 12 14:28:00 2022)[root@GreatSQL][(none)]>\s
--------------
mysql Ver 8.0.25-16 for Linux on x86_64 (GreatSQL (GPL), Release 16, Revision 8bb0e5af297)
...
Uptime: 1 min 38 sec
Threads: 11 Questions: 52 Slow queries: 0 Opens: 145 Flush tables: 3 Open tables: 62 Queries per second avg: 0.530
--------------
(Tue Jul 12 14:28:05 2022)[root@GreatSQL][(none)]>select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| group_replication_applier | 396465ad-01ab-11ed-9c1a-0242ac120002 | 172.18.0.2 | 3306 | ONLINE | PRIMARY | 8.0.25 |
| group_replication_applier | 3a4eabbd-01ab-11ed-a7ea-0242ac120003 | 172.18.0.3 | 3306 | ONLINE | SECONDARY | 8.0.25 |
| group_replication_applier | 3c707b56-01ab-11ed-969b-0242ac120004 | 172.18.0.4 | 3306 | ONLINE | ARBITRATOR | 8.0.25 |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
3 rows in set (0.01 sec)
可以看到，包含仲裁节点的三节点MGR集群已自动构建完毕。
如果想在Docker环境下逐个节点手动构建MGR集群，可以参考这篇文档在Docker中部署GreatSQL并构建MGR集群。
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