使用 Ansible 安裝 Redis Replication

之前筆記 在 CentOS 7 上安裝 Redis Replication (Redis 5) 紀錄到使用單一 shell script 來安裝完整 Redis Replication (Master,Slave 與 Sentinell),後來同事提到這類安裝最好是透過 Ansible 處理,所以我就來試試囉

原則上整個安裝流程與步驟是依照 在 CentOS 7 上安裝 Redis Replication (Redis 5) 用 Ansible 語法改寫而來的

另外這是我第一次寫 Ansible,用得不對的地方請大家指教

基本環境說明

  1. Azure VM B1s (1 vcpu,2GiB memory) X 3
  2. CentOS-based 7.7
  3. Redis 5.0.7
  4. epel-release.noarch 0:7-11
  5. ius-release.noarch 0:2-1.el7.ius
  6. ansible 2.9.3
  7. python 2.7.5

安裝語法

  1. 準備 redis config 與 service 的 template

    • master and slave config

      我用 config.j2 做範例

      dir /data/redis
      bind {{item.value.ip}}
      requirepass {{redispass}}
      {% if item.value.role == 'slave' %}
      replicaof {{item.value.masterip}} {{item.value.masterport}}
      {% endif %}
      masterauth {{redispass}}
      port {{item.value.port}}
      pidfile /var/run/redis_{{item.value.port}}.pid
      {{item.value.rdb}}
      rename-command KEYS ""
      maxclients 10000
      {{item.value.aof}}
      {{item.value.aofpolicy}}
      
    • sentine config

      我用 sentinel.j2 做範例

      bind {{item.value.ip}}
      port {{item.value.port}}
      
      {% for master in master_dic %}
      dir /data/redis
      sentinel monitor master_{{ loop.index }} {{master.value.ip}} {{master.value.port}} {{ 1 if sentinels|length < 2 else (sentinels|length)-2 }}
      sentinel auth-pass master_{{ loop.index }} {{redispass}}
      sentinel down-after-milliseconds master_{{ loop.index }}  3000
      sentinel parallel-syncs master_{{ loop.index }}  1
      sentinel failover-timeout master_{{ loop.index }}  18000
      {% endfor %}
      
    • service

      我用 service.j2 做範例

      [Unit]
      Description=Redis persistent key-value database
      After=network.target
      After=network-online.target
      Wants=network-online.target
      
      [Service]
      {% if item.value.role == 'sentinel' %}
      ExecStart=/usr/bin/redis-sentinel /etc/redis/redis_{{item.value.port}}.conf --supervised systemd
      {% else %}
      ExecStart=/usr/bin/redis-server /etc/redis/redis_{{item.value.port}}.conf --supervised systemd
      {% endif %}
      
      ExecStop=/usr/libexec/redis-shutdown
      Type=notify
      User=redis
      Group=redis
      RuntimeDirectory=redis_{{item.value.port}}
      RuntimeDirectoryMode=0755
      
      [Install]
      WantedBy=multi-user.target
      
  2. 指定安裝的 host 與 data

    • inventory.ini

      redis-nodes]
      node11 ansible_host=10.0.0.4  ip=10.0.0.4  ansible_user=root ansible_password=pass.123 ansible_become_password=pass.123
      node12 ansible_host=10.0.0.12 ip=10.0.0.12  ansible_user=root ansible_password=pass.123 ansible_become_password=pass.123
      
    • data.yml

      redispass: pass.123
      masters:
        redis1:
          ip: 10.0.0.4
          port: 6379
          role: master
          aof: appendonly no
          aofpolicy: appendfsync no
          rdb : |
            save ""
        redis2:
          ip: 10.0.0.12
          port: 6379
          role: master
          aof: appendonly no
          aofpolicy: appendfsync no
          rdb : |
            save ""
      slaves:
        redis1:
          ip: 10.0.0.12
          port: 6380
          role: slave
          masterip: 10.0.0.4
          masterport: 6379
          aof: appendonly no
          aofpolicy: appendfsync no
          rdb : |
            save ""
        redis2:
          ip: 10.0.0.4
          port: 6380
          role: slave
          masterip: 10.0.0.12
          masterport: 6379
          aof: appendonly no
          aofpolicy: appendfsync no
          rdb : |
            save ""
      sentinels:
        redis3:
          ip: 10.0.0.12
          port: 26379
          role: sentinel
        redis4:
          ip: 10.0.0.12
          port: 26380
          role: sentinel
        redis5:
          ip: 10.0.0.4
          port: 26379
          role: sentinel
      
  3. 安裝腳本

    我用 install.yml 做範

        ---
        - name: Install Tools
          gather_facts: false
          hosts: all
          vars_files:
            - data.yml
          tasks:
            - name: Install IUS
              yum:
                name: https://centos7.iuscommunity.org/ius-release.rpm
                state: latest
            - name: Install Redis
              yum:
                name: redis5
                state: latest
            - name: Create folder for config
              file:
                path: /etc/redis
                state: directory
                mode: 0755
            - name: Create Folders
              shell: install -d -m 0755 -o redis -g redis /data /data/redis
            - name: Remove default redis service
              shell: |
                systemctl disable redis
                rm -rf /usr/lib/systemd/system/redis.service
                rm -rf /etc/systemd/system/redis.service.d
                rm -rf /etc/systemd/system/redis-sentinel.service.d
            - name: Disable SELinux
              shell: |
                setenforce 0
                sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
            - name: Allow Overcommit Memory
              sysctl:
                name: vm.overcommit_memory
                value: "1"
                state: present
                reload: yes
                ignoreerrors: yes
    
        - name: Prepare Configs
          hosts: all
          vars_files:
            - data.yml
          tasks:
            - name: Master and Slave config
              template:
                src: config.j2
                dest: "/etc/redis/redis_{{item.value.port}}.conf"
              when: ansible_host == item.value.ip
              with_items:
                - "{{ lookup('dict', masters,wantlist=True) }}"
                - "{{ lookup('dict', slaves,wantlist=True) }}"
            - name: Sentinel Config
              vars:
                master_dic: "{{ lookup('dict', masters,wantlist=True) }}"
              template:
                src: sentinel.j2
                dest: "/etc/redis/redis_{{item.value.port}}.conf"
                owner: redis
              when: ansible_host == item.value.ip
              loop: "{{ lookup('dict', sentinels,wantlist=True) }}"
            - name: Prepare Services
              template:
                src: service.j2
                dest: "/etc/systemd/system/redis_{{item.value.port}}.service"
              when: ansible_host == item.value.ip
              with_items:
                - "{{ lookup('dict', masters,wantlist=True) }}"
                - "{{ lookup('dict', slaves,wantlist=True) }}"
                - "{{ lookup('dict', sentinels,wantlist=True) }}"
        - name: Start Services
          hosts: all
          vars_files:
            - data.yml
          tasks:
            - name : Reload Service Setting
              shell: |
                systemctl daemon-reload
              when: ansible_host == item.value.ip
              with_items:
                - "{{ lookup('dict', masters,wantlist=True) }}"
                - "{{ lookup('dict', slaves,wantlist=True) }}"
                - "{{ lookup('dict', sentinels,wantlist=True) }}"
            - name: Restart Redis Service
              service:
                name: redis_{{item.value.port}}
                state: restarted
              when: ansible_host == item.value.ip
              with_items:
                - "{{ lookup('dict', masters,wantlist=True) }}"
                - "{{ lookup('dict', slaves,wantlist=True) }}"
                - "{{ lookup('dict', sentinels,wantlist=True) }}"
    
  4. 卸載腳本

    我用 uninstall.yml 做範例

        ---
        - name: Uninstall Redis
          gather_facts: false
          hosts: all
          vars_files:
            - data.yml
          tasks:
            - name: uninstall redis
              shell: |
                systemctl stop redis_{{item.value.port}}
                systemctl disable redis_{{item.value.port}}
                rm -rf /etc/redis/redis_{{item.value.port}}.conf
                rm -rf /etc/systemd/system/redis_{{item.value.port}}.service
                systemctl daemon-reload
              when: ansible_host == item.value.ip
              with_items:
                - "{{ lookup('dict', masters,wantlist=True) }}"
                - "{{ lookup('dict', slaves,wantlist=True) }}"
                - "{{ lookup('dict', sentinels,wantlist=True) }}"
    
  5. 使用方式

    • install

      ansible-playbook -i inventory.ini install.yml -vvv -b
      
    • uninstall

      ansible-playbook -i inventory.ini uninstall.yml -vvv -b
      

心得

整體來說,我個人是比較推薦使用 Ansible

  • 優點:

    1. 語法看來比較整潔
    2. 彈性也很大
  • 缺點:

    1. 不僅要熟悉 Ansible 的語法特性,
    2. 還有了解不少 module 的用途
    3. 加上我這次有用上的 Jinja2 語法要適應

我自己覺得有些進入門檻,如果排除用得好不好這個問題,其實也可以把本來的 script 直接塞進去 Ansible 執行,本來搞不定時我也想這麼做XD,但最後還是過不了自己那關

雖然我覺得還是有好幾段語法可以改用 Ansible module 或是加上執行前的條件確認,但初步來說已經達成目標,成果還算滿意,暫時就先這樣囉,有機會再來改善吧

完整原始碼在 yowko/ansible-install-redis

參考資訊

  1. 在 CentOS 7 上安裝 Redis Replication (Redis 5)
  2. Ansible中文权威指南
  3. yowko/ansible-install-redis