Clever Geek Handbook

Desvendando Loops Ansible

Este post cobre os seguintes módulos de loop Ansible: with_items, with_nested, with_subelements, with_dict.



Todos esses com * já estão obsoletos e é recomendado o uso de loop.



Fonte



Uma das minhas funções na Chromatic é como membro da equipe DevOps. Entre outras coisas, isso inclui trabalhar com nossos servidores e os servidores de nossos clientes. Isso, por sua vez, significa que passo muito tempo trabalhando com o Ansible , uma ferramenta popular para provisionar, configurar e implantar servidores e aplicativos.



Para simplificar, a máquina que executa o Ansible executa comandos em outra máquina via SSH. Esses comandos são especificados declarativamente (opcional) usando pequenas seções de YAML chamadas de tarefas. Essas TAREFAS chamam módulos Ansible que se especializam em executar opções em certos componentes, como arquivos, bancos de dados, etc.



Por exemplo, a seguinte tarefa usa o módulo Arquivo ( documentação , código ) para criar um diretório específico se ele ainda não existir e modifica seus atributos se eles ainda não estiverem definidos corretamente:



- file:
    path: /home/jenkins/.ssh
    state: directory
    owner: jenkins
    group: jenkins
    mode: 700


Várias tarefas relacionadas a uma tarefa são agrupadas em funções, e várias funções podem ser agrupadas em manuais. Você pode então usar o manual para executar exatamente as mesmas etapas de configuração em qualquer número de servidores ao mesmo tempo.



O Ansible é declarativo?



TASKS Ansible , , TASKS. , , , . , Ansible Copy, . Ansible , :



- name: Copy SSH config file into Alice’s .ssh directory.
  copy:
    src: files/config
    dest: /home/alice/.ssh/config
    owner: alice
    group: alice
    mode: 0600


, , bash, scp, chown chmod. Ansible , .



, , — , , .



, Ansible, — TASKS . , Ansible , , — PHP, .



, Ansible. Loops , «loops _ + lookup(), ». (Lookups) — Ansible, « Ansible », Loops Ansible Github, .



Ansible « », , . Ansible, , , .



Ansible



TASKS, , , , , ( : , , , , !)



:



  1. , : alice, bob, carol dan.



  2. , : .ssh/ loops.



  3. , . , alice :





/home/alice/
├── .ssh/
├── bob/
├── carol/
├── dan/
└── loops/


1. WITH_ITEMS



Ansible , chuck , :



- name: Remove user ‘Chuck’ from the system.
  user:
    name: chuck
    state: absent
    remove: yes


— , Chuck Craig — with_items. with_items ( ), ( ):



- name: Remove users ‘Chuck’ and ‘Craig’ from the system.
  user:
    name: "{{ item }}"
    state: absent
    remove: yes
  with_items:
    - chuck
    - craig


, with_items , alice bob:





users_with_items:
  - name: "alice"
    personal_directories:
      - "bob"
      - "carol"
      - "dan"
  - name: "bob"
    personal_directories:
      - "alice"
      - "carol"
      - "dan"


TASKS


- name: "Loop 1: create users using 'with_items'."
  user:
    name: "{{ item.name }}"
  with_items: "{{ users_with_items }}"


Ansible User users_with_items. , , , , personal_directories ( , personal_directories — ).



Ansible ( Ansible ): TASKS , . , , personal_directories TASKS (. . User, File).



with_items , PHP:



<?php

foreach ($users_with_items as $user) {
  // Do something with $user...
}


, , :



• item.name .



• with_items, .



, Ansible item, item.property.





/home/
├── alice/
└── bob/


2: , WITH_NESTED



: 2 , 1. chown failed: failed to look up user



, users_with_items 1, , common_directories, , . , ( PHP), -, :



<?php

foreach ($users_with_items as $user) {
  foreach ($common_directories as $directory) {
    // Create $directory for $user...
  }
}


Ansible with_nested. with_nested , :





users_with_items:
  - name: "alice"
    personal_directories:
      - "bob"
      - "carol"
      - "dan"
  - name: "bob"
    personal_directories:
      - "alice"
      - "carol"
      - "dan"

common_directories:
  - ".ssh"
  - "loops


TASKS


# Note that this does not set correct permissions on /home/{{ item.x.name }}/.ssh!
- name: "Loop 2: create common users' directories using 'with_nested'."
  file:
    dest: "/home/{{ item.0.name }}/{{ item.1 }}"
    owner: "{{ item.0.name }}"
    group: "{{ item.0.name }}"
    state: directory
  with_nested:
    - "{{ users_with_items }}"
    - "{{ common_directories }}"


, with_nested , item.0 ( users_with_items) item.1 ( common_directories) . , , /home/alice/.ssh .





/home/
├── alice/
│   ├── .ssh/
│   └── loops/
└── bob/
    ├── .ssh/
    └── loops/


3: , WITH_SUBELEMENTS



: 3 , 1. chown failed: failed to look up user



with_subelements , users_with_items 1. PHP :



<?php

foreach ($users_with_items as $user) {
  foreach ($user['personal_directories'] as $directory) {
    // Create $directory for $user...
  }
}


, $users_with_items $user['personal_directories'] .





users_with_items:
  - name: "alice"
    personal_directories:
      - "bob"
      - "carol"
      - "dan"
  - name: "bob"
    personal_directories:
      - "alice"
      - "carol"
      - "dan"


TASKS


- name: "Loop 3: create personal users' directories using 'with_subelements'."
  file:
    dest: "/home/{{ item.0.name }}/{{ item.1 }}"
    owner: "{{ item.0.name }}"
    group: "{{ item.0.name }}"
    state: directory
  with_subelements:
    - "{{ users_with_items }}"
    - personal_directories


with_subelements , with_nested, , , — personal_directories. 2, ( ) /home/alice/bob.





/home/
├── alice/
│   ├── .ssh/
│   ├── bob/
│   ├── carol/
│   ├── dan/
│   └── loops/
└── bob/
    ├── .ssh/
    ├── alice/
    ├── carol/
    ├── dan/
    └── loops/


4: WITH_DICT



3 , alice bob, , , carol dan. users_with_dict Ansible with_dict.



, (dict dictionary — Python ); with_dict , . , Ansible, PHP :



<?php

foreach ($users_with_dict as $user => $properties) {
  // Create a user named $user...
}




users_with_dict:
  carol:
    common_directories: "{{ common_directories }}"
  dan:
    common_directories: "{{ common_directories }}"


TASKS


- name: "Loop 4: create users using 'with_dict'."
  user:
    name: "{{ item.key }}"
  with_dict: "{{ users_with_dict }}"


with_dict . , , , dict with_dict (, , with_dict ).





/home/
├── alice/
│   ├── .ssh/
│   ├── bob/
│   ├── carol/
│   ├── dan/
│   └── loops/
├── bob/
│   ├── .ssh/
│   ├── alice/
│   ├── carol/
│   ├── dan/
│   └── loops/
├── carol/
└── dan/


5: ,



users_with_dict, Ansible, -. alice, bob, carol dan, with_nested /home/. , , , TASKS:



  • Ansible

    • Ansible
    • Jinja2 ()
    • Jinja2 ()




common_directories:
  - ".ssh"
  - "loops"


TASKS


- name: "Get list of extant users."
  shell: "find * -type d -prune | sort"
  args:
    chdir: "/home"
  register: "home_directories"
  changed_when: false

- name: "Loop 5: create personal user directories if they don't exist."
  file:
    dest: "/home/{{ item.0 }}/{{ item.1 }}"
    owner: "{{ item.0 }}"
    group: "{{ item.0 }}"
    state: directory
  with_nested:
    - "{{ home_directories.stdout_lines }}"
    - "{{ home_directories.stdout_lines | union(common_directories) }}"
  when: "'{{ item.0 }}' != '{{ item.1 }}'"


TASKS: shell find , file .



/home find \ -type d -prune | sort ( shell) , /home, , , .



home_directories register: "home_directories" . , , :



"stdout_lines": [
  "alice",
  "bob",
  "carol",
  "dan",
],


( ) with_nested , :



  1. with_nested :


- "{{ home_directories.stdout_lines | union(common_directories) }}"


  1. , when TASKS:



    when: "'{{ item.0 }}' != '{{ item.1 }}'"




. with_nested Jinja2 TASKS ( home_directories.stdout_lines). Jinja:



  • (home_directories.stdout_lines)
  • (|)
  • , (union (common_directories))


, home_directories.stdout_lines common_directories :



item:
  - .ssh
  - alice
  - bob
  - carol
  - dan
  - loops


, with_nested home_directories.stdout_lines ( with_nested) , .



, — , , , ! (, /home/alice/alice, /home/bob/bob . .) Ansible — when — :



when: "'{{ item.0 }}' != '{{ item.1 }}'"


, home_directories.stdout_lines home_directories.stdout_lines ( Ansible Loops, «… when with_items ( ), when »). PHP , , :



<?php

$users = ['alice', 'bob', 'carol', 'dan'];
$common_directories = ['.ssh', 'loops'];
$directories = $user + $common_directories;

foreach ($users as $user) {
  foreach ($directories as $directory) {
    if ($directory != $user) {
      // Create the directory…
    }
  }
}


, , .





/home/
├── alice/
│   ├── .ssh/
│   ├── bob/
│   ├── carol/
│   ├── dan/
│   └── loops/
├── bob/
│   ├── .ssh/
│   ├── alice/
│   ├── carol/
│   ├── dan/
│   └── loops/
├── carol/
│   ├── .ssh/
│   ├── alice/
│   ├── bob/
│   ├── dan/
│   └── loops/
└── dan/
    ├── .ssh/
    ├── alice/
    ├── bob/
    ├── carol/
    └── loops/




Ansible . ( Ansible), , (with_nested? with_subitems?) .



, , TASKS, ( , array_filter, array_reduce, array_map , ). , , — — .



Espero que este post o ajude a sair da minha dificuldade inicial. Para isso, construí uma máquina virtual Vagrant (o Vagrant suporta nativamente o uso de Ansible para provisionamento) e um playbook de Ansible que usei para criar e testar esses exemplos). Basta seguir as instruções no README para executar os exemplos deste post ou tente o seu próprio. Se você tiver dúvidas ou comentários, tweet em @chromaticHQ!



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