Ansible 自動化的操作模式

下面來看一下如何透過 Ansible 來做自動化部署,參考文章 – https://docs.ansible.com/ansible/latest/getting_started/get_started_ansible.html

測試環境 CentOS 9 Stream (虛擬機)

架構需求如下系統可以分為 Control node ( Ansible 控制端) 與 Managed nodes (被 Ansible 控制端)

Control node ( Ansible 控制端) IP: 192.168.31.131
Managed nodes (被 Ansible 控制端) IP: 192.168.31.178

Managed nodes

系統預設都安裝 Python 與 SSH-Server 就可以運作.

Control node

接下來所有設定皆是在 Control node 來設定.

安裝 Ansible
官網是用 pip 來安裝 Ansible.
```
[root@localhost ~]# yum install pip
[root@localhost ~]# pip install ansible
[root@localhost ~]# pip install ansible-lint
```
建議安裝 ansible-lint 該程式可以幫忙檢查 Playbook 的 ymal 檔案是否正常.

SSH 免密碼的登入方式
Control node 是透過 SSH 的方式去連到 Managed node 來工作,所以要先把 Control node 的 public SSH key 加到 Managed node 的 authorized_keys 檔案 (實現 SSH 免密碼的登入方式),更多關於 SSH 基於 Key 的驗證請參考 – https://benjr.tw/106336

產生 SSH Public / Private Key (如需輸入 SSH Private Key PassPhrase 時須使用 SSH_Agent 去避免輸入 PassPhase 的密碼)

[root@localhost ~]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa
Your public key has been saved in /root/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:gDEFTV2X0g7/X3WiVNO0xYU57wUsPWwCqPzi4yMXmCo root@localhost.localdomain
The key's randomart image is:
+---[RSA 3072]----+
|    +=o. ooo.= *=|
|     +. o o.= & =|
|    ....   = = B |
|      o.    + . =|
|     o .S  . o o+|
|    o o .   . . o|
|   . . o       ..|
|E . . =         .|
| .   +.o         |
+----[SHA256]-----+

把 Control node 的 public SSH key 加到 Managed node 的 authorized_keys 檔案 .

[root@localhost ~]# ssh-copy-id root@192.168.31.178
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.31.178 (192.168.31.178)' can't be established.
ED25519 key fingerprint is SHA256:PgFJeh+W+iNzarxpeUxtVg1ewnvb3GZTAt87Oxq260E.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@192.168.31.178's password:

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'root@192.168.31.178'"
and check to make sure that only the key(s) you wanted were added.

這樣就實現了 SSH 免密碼的登入方式,測試一下連線到 Managed nodes ( IP: 192.168.31.178 )

[root@localhost ~]# ssh root@192.168.31.178
Activate the web console with: systemctl enable --now cockpit.socket

Last failed login: Thu May 16 17:31:43 CST 2024 from 192.168.31.131 on ssh:notty
There was 1 failed login attempt since the last successful login.
Last login: Thu May 16 17:20:50 2024 from 192.168.31.1
[root@localhost ~]# exit
登出
Connection to 192.168.31.178 closed.

準備工作完成.

建立一個測試用的資料夾

[root@localhost ~]# mkdir ansible_quickstart && cd ansible_quickstart
[root@localhost ansible_quickstart]#

簡單測試一下 localhost 自己本身,並使用系統提供的 ping 模組(後面說明)

[root@localhost ansible_quickstart]# ansible localhost -m ping
[WARNING]: No inventory was parsed, only implicit localhost is available
localhost | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Inventory
建立一個 Inventory 檔案 (測試時可以指定檔名) ,內容為 Managed nodes (被 Ansible 控制端) 的 IP address 或是 fully qualified domain name (FQDN)

[root@localhost ansible_quickstart]# vi inventory.ini
[myhosts]
192.168.31.178

[yourhosts]
192.168.31.179

驗證 inventory 檔案的正確與否.

[root@localhost ansible_quickstart]# ansible-inventory -i inventory.ini --list
{
    "_meta": {
        "hostvars": {}
    },
    "all": {
        "children": [
            "ungrouped",
            "myhosts",
            "yourhosts"
        ]
    },
    "myhosts": {
        "hosts": [
            "192.168.31.178"
        ]
    },
    "yourhosts": {
        "hosts": [
            "192.168.31.179"
        ]
    }
}

操作模式
模式有 Ad-Hoc , Playbook 兩種.

Ad-Hoc command 的指令操作模式
透過 Ansible 內建的 Ping 模組來檢查 Hosts 的 python 與是否有在線上 (使用指定的 inventory 檔案內的 myhosts 清單).

[root@localhost ansible_quickstart]# ansible myhosts -m ping -i inventory.ini
192.168.31.178 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}

因為 yourhost 指定的 IP 機器不存在,所以會顯示錯誤.

[root@localhost ansible_quickstart]# ansible yourhosts -m ping -i inventory.ini
192.168.31.179 | UNREACHABLE! => {
    "changed": false,
    "msg": "Failed to connect to the host via ssh: ssh: connect to host 192.168.31.179 port 22: No route to host",
    "unreachable": true
}

透過 Ansible 內建的 debug 模組

[root@localhost ansible_quickstart]# ansible myhosts -m debug -i inventory.ini
192.168.31.178 | SUCCESS => {
    "msg": "Hello world!"
}

指定指令來執行

[root@localhost ansible_quickstart]# ansible myhosts -m command -a "echo Hello World" -i inventory.ini
192.168.31.178 | CHANGED | rc=0 >>
Hello World

Playbook 透過劇本 (Playbooks) 來讓 Managed Nodes 進行指定的動作 (Plays) 和任務 (Tasks)
以上 Ad-Hoc commands 一次只能做一件事情, 依序做大量工作時需使用 Playbooks 的方式,以下定義了兩個 Task.

[root@localhost ansible_quickstart]# vi playbook.yaml
- name: My first play
  hosts: myhosts
  tasks:
   - name: Ping my hosts
     ansible.builtin.ping:

   - name: Print message
     ansible.builtin.debug:
      msg: Hello world

透過程式去檢測 yaml 內容是否無誤.

[root@localhost ansible_quickstart]# ansible-lint playbook.yaml

Passed: 0 failure(s), 0 warning(s) on 1 files. Last profile that met the validation criteria was 'production'.
A new release of ansible-lint is available: 6.22.2 → 24.5.0

執行.

[root@localhost ansible_quickstart]# ansible-playbook -i inventory.ini playbook.yaml

PLAY [My first play] ***************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************
ok: [192.168.31.178]

TASK [Ping my hosts] ***************************************************************************************************
ok: [192.168.31.178]

TASK [Print message] ***************************************************************************************************
ok: [192.168.31.178] => {
    "msg": "Hello world"
}

PLAY RECAP *************************************************************************************************************
192.168.31.178             : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

執行結果.
TASK [Gathering Facts] 預設 Ansible 會收集有關在 playbook 中有使用的清單的資訊.

TASK [Ping my hosts] TASK [Print message] 顯示為 ok 表示它運行成功.

PLAY RECAP
這邊會總結了每個主機的 Play 中所有 Task 任務的結果.

Managed nodes

Control node

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