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