上一次寫完 Ansible 簡單的指令測試
今天來介紹 playbook
playbook 簡單來說就是
- 把要執行的 ansible 指令還有可能遠端主機會使用到的檔案都集中到一個目錄內.
- 以YAML 語法來寫
- 以 ansible-playbook 指令執行
- playbook 裡面會有不同的 play ( 可以把看成要執行的script )
- 每個 play 必須有
- 要執行的 host ( 對應我們設定的 hosts 或是 inventory 檔案 )
- task ( 執行那些工作)
以下是看書上,自己的整理筆記
playbook
- A script is called a playbook.
- A playbook describes which hosts( what Ansible calls remote servers ) to configure, and an ordered list of tasks to perform on those hosts.
- Ansible runs each task in parallel across all hosts.
- Ansible waits until all hosts have completed a task before moving to the next task.
- Ansible runs the tasks in the order that you specify them.
- 使用 ansible-playbook 指令來執行
- # 例如 ansible-playbook web-notls.yml
- 如果檔案本身可以被執行
- 也可以在檔案第一行加上
- #!/usr/bin/env ansible-playbook
- 來直接執行
- Ansible playbooks written in YAML syntax.
- YAML
- Yet Another Markup Language
- Start of File
- 以 3 個 --- 開始
- 不加上去也可以
- 註解
- 以 # 來進行單行註解
- #就是註解開始
- Strings
- 不一定要加上引號
- 可是有的時候為了易讀性, 可以使用 單引號或是雙引號
- Booleans
- 使用 True 或是 Yes 都可以視為真
- 但是還是用 True 不會混亂
- Lists
They are delimited with hyphens, like this:
- My Fair Lady
- Oklahoma
- The pirates of Penzance
# inline 格式list
[My Fair Lady, Oklahoma, The Pirates of Penzance]
- Dictionaries
They look like this:
address: 742 Evergreen Terrace
city: Springfield
state: North Takoma
# inline 格式
{address: 742 Evergreen Terrace, city: Springfield, state: North Takoma}
- Line Folding
# 使用 > 符號來進行 單行摺疊, 有點類似 shell script 放在行尾的 \
# 目的在於讓一個很長的單行, 有效率地被呈現
address: >
Department of Computer Science,
A.V. Williams Building,
University of Maryland
city: College Park
state: Maryland
# address 那邊就可以看成一行
- A playbook is a list of plays
- Plays
- Every play must contain:
- * A set of hosts to configure
- * A list of tasks to be executed on those hosts
- Three common optional settings are
- name
- A comment that describes what the play is about.
- Ansible will print this out when the play starts to run.
- sudo
- If true, Ansible will run every task by sudo.
- vars
- A list of variables and values.
- 在 play 內用 {{ }} 來使用 variables
- Other optional settings are
- Handlers
A handler is similar to a task, but it runs only if it has been notified by a task.
A task will fire the notification if Ansible recognizes that the task has changed the state of the system.
# 當 task 改變系統狀態時, 會進行 notify 的動作
tasks:
- name: copy TLS key
copy: src=files/nginx.key dest={{ key_file }} owner=root mode=0600
notify: restart nginx
# handlers 可能有很多個, notify 會去比對 handlers 的名稱, 如果符合就進行該模組
handlers:
- name: restart nginx
service: name=nginx state=restarted
# 也就是說, 只有真的系統產生改變的時候, 例如 TLS key 被換掉, 才會重新啟動 nginx
- Handlers only run after all of the tasks are run, and the only run once, even they are notified multiple times.
- # Handlers 在所有tasks執行完才執行, 不管被呼叫多少次, 都只執行一次.
- hosts
- default: /etc/ansible/hosts
- Tasks
- Something to be executed on hosts
- Use different modules to do different task.
- Modules
- Modules are scripts that come packaged with Ansible and perform some kind of action on a host.
