第 2 部分 如何在 RHEL 8、Rocky Linux 8、AlmaLinux 8 设置 Consul 集群

在第一部分中，我描述了将 Consul的设置 作为 ETCD 的替代品。
现在这里将设置keepalived、haproxy和patoni。

我在第一部分中已经安装了所需的包，所以让我们从keepalived的配置开始。

首先我们需要为 VRRP 协议打开 firewalld 防火墙：

[root@patroni-01 ~]# firewall-cmd --add-rich-rule='rule protocol value="vrrp" accept' --permanent
success
[root@patroni-01 ~]# firewall-cmd --reload
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下一部分将是keepalived的配置：

 [root@patroni-01 /]# cat /etc/keepalived/keepalived.conf
 vrrp_script haproxy {
         script "killall -0 haproxy"
         interval 2
         weight 2
 }
vrrp_instance VI_1 {
         state MASTER
         interface ens160
         virtual_router_id 51
         priority 255
         advert_int 1
         authentication {
               auth_type PASS
               auth_pass new_password
         }
         virtual_ipaddress {
               192.168.198.200/24
         }
         track_script {
         haproxy
         }
 }
 [root@patroni-01 /]#
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优先级定义了默认角色，在我的例子中，255 是主角色。

用于patoni-02 上的备份角色的keepalived.conf：

 [root@patroni-02 /]# cat /etc/keepalived/keepalived.conf
 vrrp_script haproxy {
         script "killall -0 haproxy"
         interval 2
         weight 2
 }
 vrrp_instance VI_1 {
         state BACKUP
         interface ens160
         virtual_router_id 51
         priority 254
         advert_int 1
         authentication {
               auth_type PASS
               auth_pass new_password
         }
         virtual_ipaddress {
               192.168.198.200/24
         }
         track_script {
         haproxy
         }
 }
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用于patoni-03 上的备份角色的keepalived.conf：

 [root@patroni-03 /]# cat /etc/keepalived/keepalived.conf
 vrrp_script haproxy {
         script "killall -0 haproxy"
         interval 2
         weight 2
 }
 vrrp_instance VI_1 {
         state BACKUP
         interface ens160
         virtual_router_id 51
         priority 254
         advert_int 1
         authentication {
               auth_type PASS
               auth_pass new_password
         }
         virtual_ipaddress {
               192.168.198.200/24
         }
         track_script {
         haproxy
         }
 }
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检查所有三个节点的状态。：
patoni-01 作为 MASTER：

$ [root@patroni-01 /]# journalctl -u keepalived
$ Mar 25 13:04:45 patroni-01.patroni.test Keepalived_vrrp[11468]: (VI_1) Entering MASTER STATE
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patroni-02 作为备节点：

$ journalctl -u keepalived
$ Mar 25 14:20:18 patroni-02.patroni.test Keepalived_vrrp[1484]: (VI_1) Entering BACKUP STATE
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patroni-03 作为备节点：

$ journalctl -u keepalived
$ Mar 25 14:21:56 patroni-03.patroni.test Keepalived_vrrp[1465]: (VI_1) Entering BACKUP STATE
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下一步 haproxy。
首先，我们需要为 haproxy 适配 SELinux 或将其关闭：

$ [root@patroni-01 /]#setsebool -P haproxy_connect_any=1
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haproxy.cfg 在所有三台服务器上都是相同的：

 [root@patroni-01 /]# cat /etc/haproxy/haproxy.cfg
 global
     maxconn 100
 
 defaults
     log global
     mode tcp
     retries 2
     timeout client 30m
     timeout connect 4s
     timeout server 30m
     timeout check 5s
 
 listen stats
     mode http
     bind *:7000
     stats enable
     stats uri /
     # stats auth haproxy:haproxy
     # stats refresh 10s
 
 listen PG1
     bind *:5000
     option httpchk
     http-check expect status 200
     default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
     server postgresql_192.168.198.132_5432 192.168.198.132:5432 maxconn 100 check port 8008
     server postgresql_192.168.198.133_5432 192.168.198.133:5432 maxconn 100 check port 8008
     server postgresql_192.168.198.134_5432 192.168.198.134:5432 maxconn 100 check port 8008
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启动和启用 haproxy：

$ [root@patroni-01 /]# systemctl start haproxy
$ [root@patroni-01 /]# systemctl enable haproxy
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现在有趣的部分，Patroni。
起初，通过从 RPM Pachages 中安装 Patroni，缺少依赖关系，缺少 python3-urllib3：

 [root@patroni-01 pgdata]# dnf install python3-urllib3
 Last metadata expiration check: 5:18:38 ago on Mon 11 Apr 2022 11:06:33 AM CEST.
 Dependencies resolved.
 ==========================================================================================================================================================================================================================================================================================
  Package                                                                   Architecture                                                     Version                                                                Repository                                                        Size
 ==========================================================================================================================================================================================================================================================================================
 Installing:
  python3-urllib3                                                           noarch                                                           1.24.2-5.el8                                                           baseos                                                           176 k
 Installing dependencies:
  python3-pysocks                                                           noarch                                                           1.6.8-3.el8                                                            baseos                                                            33 k
 
 Transaction Summary
 ==========================================================================================================================================================================================================================================================================================
 Install  2 Packages
 
 Total download size: 209 k
 Installed size: 681 k
 Is this ok [y/N]: y
 Downloading Packages:
 (1/2): python3-pysocks-1.6.8-3.el8.noarch.rpm                                                                                                                                                                                                             274 kB/s |  33 kB     00:00
 (2/2): python3-urllib3-1.24.2-5.el8.noarch.rpm                                                                                                                                                                                                            1.0 MB/s | 176 kB     00:00
 ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Total                                                                                                                                                                                                                                                     469 kB/s | 209 kB     00:00
 Running transaction check
 Transaction check succeeded.
 Running transaction test
 Transaction test succeeded.
 Running transaction
   Preparing        :                                                                                                                                                                                                                                                                  1/1
   Installing       : python3-pysocks-1.6.8-3.el8.noarch                                                                                                                                                                                                                               1/2
   Installing       : python3-urllib3-1.24.2-5.el8.noarch                                                                                                                                                                                                                              2/2
   Running scriptlet: python3-urllib3-1.24.2-5.el8.noarch                                                                                                                                                                                                                              2/2
   Verifying        : python3-pysocks-1.6.8-3.el8.noarch                                                                                                                                                                                                                               1/2
   Verifying        : python3-urllib3-1.24.2-5.el8.noarch                                                                                                                                                                                                                              2/2
 
 Installed:
   python3-pysocks-1.6.8-3.el8.noarch                                                                                                          python3-urllib3-1.24.2-5.el8.noarch
 
 Complete!
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Patroni 需要一个信息，其中一个consul节点在开始时是主节点。
此信息来自参数“bootstrap”：仅在启动时在主节点上为 true。

 [root@patroni-01 consul.d]# cat consul.json-dist.hcl
 {
     "bootstrap": true,
     "server": true,
     "data_dir": "/pgdata/consul",
     "log_level": "INFO"
     "disable_update_check": true,
     "disable_anonymous_signature": true,
     "advertise_addr": "192.168.198.132",
     "bind_addr": "192.168.198.132",
     "bootstrap_expect": 3,
     "client_addr": "0.0.0.0",
     "domain": "patroni.test",
     "enable_script_checks": true,
     "dns_config": {
         "enable_truncate": true,
         "only_passing": true
     },
     "enable_syslog": true,
     "encrypt": "ueX3vI8HI63FR/VE+Yv1T4+x7mrrNIU7F2bDNfPVR9g=",
     "leave_on_terminate": true,
     "log_level": "INFO",
     "rejoin_after_leave": true,
     "retry_join": [
         "patroni-01",
         "patroni-02",
         "patroni-03"
     ],
     "server": true,
     "start_join": [
         "patroni-01",
         "patroni-02",
         "patroni-03"
     ],
     "ui_config.enabled": true
 }
 [root@patroni-01 consul.d]#
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现在是 Patroni，这类似于使用 etcd 的 Patroni。
通过使用 etcd，patroni.yml 文件中有一个部分 etcd，它被部分 consul 替换：

 [root@patroni-01 patroni]# cat patroni.yml
 name: "patroni-01.patroni.test"
 scope: PG1
 namespace: /patroni.test/
 consul:
   url: http://127.0.0.1:8500
   register_service: true
 postgresql:
   connect_address: "patroni-01.patroni.test:5432"
   bin_dir: /usr/pgsql-14/bin
   data_dir: /pgdata/14/data
   authentication:
     replication:
       username: replicator
       password: replicator
     superuser:
       username: postgres
       password: postgres
   listen: 192.168.198.132:5432
 restapi:
   connect_address: "patroni-01.patroni.test:8008"
   listen: "patroni-01.patroni.test:8008"
 bootstrap:
   dcs:
     postgresql:
       use_pg_rewind: true
       use_slots: true
       parameters:
         wal_level: 'hot_standby'
         hot_standby: "on"
         wal_keep_segments: 8
         max_replication_slots: 10
         wal_log_hints: "on"
         listen_addresses: '*'
         port: 5432
         logging_collector: 'on'
         log_truncate_on_rotation: 'on'
         log_filename: 'postgresql-%a.log'
         log_rotation_age: '1440'
         log_line_prefix: '%m - %l - %p - %h - %u@%d - %x'
         log_directory: 'pg_log'
         log_min_messages: 'WARNING'
         log_autovacuum_min_duration: '60s'
         log_min_error_statement: 'NOTICE'
         log_min_duration_statement: '30s'
         log_checkpoints: 'on'
         log_statement: 'ddl'
         log_lock_waits: 'on'
         log_temp_files: '0'
         log_timezone: 'Europe/Zurich'
         log_connections: 'on'
         log_disconnections: 'on'
         log_duration: 'on'
         client_min_messages: 'WARNING'
         wal_level: 'replica'
         hot_standby_feedback: 'on'
         max_wal_senders: '10'
         shared_buffers: '1024MB'
         work_mem: '8MB'
         effective_cache_size: '3072MB'
         maintenance_work_mem: '64MB'
         wal_compression: 'off'
         max_wal_senders: '20'
         shared_preload_libraries: 'pg_stat_statements'
         autovacuum_max_workers: '6'
         autovacuum_vacuum_scale_factor: '0.1'
         autovacuum_vacuum_threshold: '50'
         archive_mode: 'on'
         archive_command: '/bin/true'
         wal_log_hints: 'on'
         ssl: "on"
         ssl_ciphers: "TLSv1.2:!aNULL:!eNULL"
         ssl_cert_file: /pgdata/certs/server.crt
         ssl_key_file: /pgdata/certs/server.key
   users:
     app_user:
       password: "aZ5QrESZ"
   pg_hba:
     - local all all  scram-sha-256
     - hostssl all all 127.0.0.1/32 scram-sha-256
     - hostssl all all ::1/128 scram-sha-256
     - hostssl all all ::1/128 scram-sha-256
     - hostssl all all 0.0.0.0/0 scram-sha-256
     - hostssl replication replicator patroni-01.patroni.test scram-sha-256
     - hostssl replication replicator patroni-01.patroni.test scram-sha-256
     - hostssl replication replicator patroni-01.patroni.test scram-sha-256
   initdb:
     - encoding: UTF8
 [root@patroni-01 patroni]#
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此示例设置中三个节点上的patroni.yml 中的唯一区别是：
名称：“patroni-01.patroni.test”需要适应“patroni-02.patroni.test”或“patroni-03.patroni”。 test”

在 postgresql 下：
connect_address: “patroni-01.patroni.test:5432” 需要适配为 “patroni-02.patroni.test:5432” 或 “patroni-03.patroni.test:5432”。
监听：192.168.198.132:5432 需要适配对应的 IP 192.168.198.133:5432 或 192.168.198.134:5432。

在 reatapi 下：
connect_address：“patroni-01.patroni.test:8008”到“patroni-02.patroni.test:8008”或“patroni-02.patroni.test:8008”。
监听：“patroni-01.patroni.test:8008”到“patroni-02.patroni.test:8008”或“patroni-02.patroni.test:8008”。

在我的例子中，patroni-01 是consul领袖节点，所以在这里我们需要先启动patroni，成为patroni集群中的领袖节点。
意味着在任何情况下，consul 领袖节点都将成为patroni领袖节点，在故障转移的情况下也是如此。

$ postgres@patroni-01: patronictl list
$ + Cluster: PG1 (7358967191570897068) -----------------+---------+----+-----------+
$ | Member                  | Host            | Role    | State   | TL | Lag in MB |
$ +-------------------------+-----------------+---------+---------+----+-----------+
$ | patroni-01.patroni.test | 192.168.198.132 | Leader  | running |  2 |           |
$ | patroni-02.patroni.test | 192.168.198.133 | Replica | running |  2 |         0 |
$ | patroni-03.patroni.test | 192.168.198.134 | Replica | running |  2 |         0 |
$ +-------------------------+-----------------+---------+---------+----+-----------+
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原文标题：How to setup a Consul Cluster on RHEL 8, Rocky Linux 8, AlmaLinux 8 part 2
原文作者：Karsten Lenz
原文地址：https://www.dbi-services.com/blog/how-to-setup-a-consul-cluster-on-rhel-8-rocky-linux-8-almalinux-8-part-2/