如何开始测试Ansible，将项目重构一年，而不是一团糟

这是DevOps-40 2020-03-18上的性能记录：

从第二次提交开始，任何代码都将成为旧代码，因为 最初的想法开始脱离现实。这既不是好事也不是坏事，这是一个既难以争论又必须相处的前提。此过程的一部分是重构。将基础结构重构为代码。让故事开始如何在一年内重构Ansible，而不是一团糟。

传统开始

第一天：零病人

从前有一个有条件的项目。它有一个Dev开发团队和Ops工程师。他们解决了相同的问题：如何部署服务器和运行应用程序。问题是每个团队都以自己的方式解决了这个问题。该项目决定使用Ansible在Dev和Ops团队之间同步知识。

第89天：传统的诞生

, , legacy. ?

• , — .
• .
• Ansible / Python / Bash / Terraform! !
• Full Stack Overflow Developer stackoverflow, , .

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- hosts: localhost
  tasks:
    - shell: echo -n Z >> a.txt && cat a.txt
      register: output
      delay: 1
      retries: 5
      until: not output.stdout.find("ZZZ")

№ 109:

IaC / / , . , .

IaC

№ 139: ?

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2. ?
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№ 149:

e . . , . - , confluence, " ?" " ?" . : / . , , - .

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Ansible

Ansible , , .

№ -997: SDS provision

Ansible SDS (Software Defined Storage).
, , 60-90 , . e2e , .. , . . .

№ -701: Ansible test kitchen

Ansible , test kitchen / kitchen-ci inspec. Ruby ( : YML ansible?) 40 10 . .

, - . 13 2 , 70 , 2 . XP (extreme programming) .. 70 .

№ -601: Ansible molecule

testkitchen, docker . , 20-25 7 .

17 45 28 2 jenkins slave.

№ 167: Ansible

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, , , jira, google docs . , , . , - , , .

:

• Eat.
• Sleep.
• Code.
• IaC test.
• Repeat

.

, .

№ 181: Green Build Master

Green Build Master. , jenkins. , :

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• - , .

№ 193: unit

— , . , .

№ 211: unit integration

unit , . .. , , .

jenkins , / , .

Jenkins + Docker + Ansible = Tests

1. Checkout repo and generate build stages.
2. Run lint playbook stages in parallel.
3. Run lint role stages in parallel.
4. Run syntax check role stages in parallel.
5. Run test role stages in parallel.
   
   1. Lint role.
   2. Check dependency on other roles.
   3. Check syntax.
   4. Create docker instance
   5. Run molecule/default/playbook.yml.
   6. Check idempotency.
6. Run integration tests
7. Finish

№ 271: Bus Factor

- . e. code review . , , , .. .

. , , . jenkins + bitbucket + jira.

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- get_url:
    url: "{{ actk_certs }}/{{ item.1 }}"
    dest: "{{ actk_src_tmp }}/"
    username: "{{ actk_mvn_user }}"
    password: "{{ actk_mvn_pass }}"
  with_subelements:
    - "{{ actk_cert_list }}"
    - "{{ actk_certs }}"
  delegate_to: localhost

- copy:
    src: "{{ actk_src_tmp }}/{{ item.1 }}"
    dest: "{{ actk_dst_tmp }}"
  with_subelements:
    - "{{ actk_cert_list }}"
    - "{{ actk_certs }}"

, .

get_url:
    url: "{{ actk_certs }}/{{ actk_item }}"
    dest: "{{ actk_src_tmp }}/{{ actk_item }}"
    username: "{{ actk_mvn_user }}"
    password: "{{ actk_mvn_pass }}"
  loop_control:
    loop_var: actk_item
  with_items: "{{ actk_cert_list }}"
  delegate_to: localhost

- copy:
    src: "{{ actk_src_tmp }}/{{ actk_item }}"
    dest: "{{ actk_dst_tmp }}"
  loop_control:
    loop_var: actk_item
  with_items: "{{ actk_cert_list }}"

№ 311:

, . " , ". docker, . testinfra ansible verifier - .

:

1. docker.
2. , .
3. - .
4. .
5. .

Pipeline jenkins

1. Generate build stages.
2. Lint all in parallel.
3. Run test role stages in parallel.
4. Finish.

Lessons learned

Avoid global variables

Ansible , workaround private_role_vars, .

. role_a role_b

# cat role_a/defaults/main.yml
---
msg: a

# cat role_a/tasks/main.yml
---
- debug:
    msg: role_a={{ msg }}

# cat role_b/defaults/main.yml
---
msg: b

# cat role_b/tasks/main.yml
---
- set_fact:
    msg: b
- debug:
    msg: role_b={{ msg }}

- hosts: localhost
  vars:
    msg: hello
  roles:
    - role: role_a
    - role: role_b
  tasks:
    - debug:
        msg: play={{msg}}

, , . Ansible , - , .

BAD: .

# cat roles/some_role/tasks/main.yml
---
debug:
  var: java_home

GOOD: defaults .

# cat roles/some_role/defaults/main.yml
---
r__java_home:
 "{{ java_home | default('/path') }}"

# cat roles/some_role/tasks/main.yml
---
debug:
  var: r__java_home

Prefix role variables

BAD: .

# cat roles/some_role/defaults/main.yml
---
db_port: 5432

GOOD: , inventory .

# cat roles/some_role/defaults/main.yml
---
some_role__db_port: 5432

Use loop control variable

BAD: item, / -

---
- hosts: localhost
  tasks:
    - debug:
        msg: "{{ item }}"
      loop:
        - item1
        - item2

GOOD: loop_var.

---
- hosts: localhost
  tasks:
    - debug:
        msg: "{{ item_name }}"
      loop:
        - item1
        - item2
      loop_control:
        loop_var: item_name

Check input variables

, , ,

GOOD: .

- name: "Verify that required string variables are defined"
  assert:
    that: ahs_var is defined and ahs_var | length > 0 and ahs_var != None
    fail_msg: "{{ ahs_var }} needs to be set for the role to work "
    success_msg: "Required variables {{ ahs_var }} is defined"
  loop_control:
    loop_var: ahs_var
  with_items:
    - ahs_item1
    - ahs_item2
    - ahs_item3

Avoid hashes dictionaries, use flat structure

hash/dictionary , , hash/dictionary, .

BAD: hash/dictionary.

---
user:
  name: admin
  group: admin

GOOD: .

---
user_name: admin
user_group: "{{ user_name }}"

Create idempotent playbooks & roles

, .. configuration drift -. molecule, .

Avoid using command shell modules

shell , , Ansible.

Test your roles via molecule

Molecule , .

Molecule Multiple instances

molecule.yml platforms .

---
    driver:
      name: docker
    platforms:
      - name: postgresql-instance
        hostname: postgresql-instance
        image: registry.example.com/postgres10:latest
        pre_build_image: true
        override_command: false
        network_mode: host
      - name: app-instance
        hostname: app-instance
        pre_build_image: true
        image: registry.example.com/docker_centos_ansible_tests
        network_mode: host

, converge.yml :

---
- name: Converge all
  hosts: all
  vars:
    ansible_user: root
  roles:
    - role: some_role

- name: Converge db
  hosts: db-instance
  roles:
    - role: some_db_role

- name: Converge app
  hosts: app-instance
  roles:
    - role: some_app_role

Ansible verifier

molecule ansible , , 3 . testinfra/inspec, , :

---
- name: Verify
  hosts: all
  tasks:
    - name: copy config
      copy:
        src: expected_standalone.conf
        dest: /root/wildfly/bin/standalone.conf
        mode: "0644"
        owner: root
        group: root
      register: config_copy_result

    - name: Certify that standalone.conf changed
      assert:
        that: not config_copy_result.changed

, smoke test:

---
  - name: Verify
    hosts: solr
    tasks:
      - command: /blah/solr/bin/solr start -s /solr_home -p 8983 -force
      - uri:
          url: http://127.0.0.1:8983/solr
          method: GET
          status_code: 200
        register: uri_result
        until: uri_result is not failed
        retries: 12
        delay: 10
      - name: Post documents to solr
        command: /blah/solr/bin/post -c master /exampledocs/books.csv

Put complex logic into modules & plugins

Ansible , , , shell , . , , .

Summarize Tips & Tricks

1. Avoid global variables.
2. Prefix role variables.
3. Use loop control variable.
4. Check input variables.
5. Avoid hashes dictionaries, use flat structure.
6. Create idempotent playbooks & roles.
7. Avoid using command shell modules.
8. Test your roles via molecule.
9. Put complex logic into modules & plugins.

, IaC. , .

Links

• Slides How to test Ansible and don't go nuts
• Video How to test Ansible and don't go nuts
• , 200 000
• Ansible: 120 VM c Coreos Centos 18
• YML ansible?
• A list of awesome IaC testing articles, speeches & links
• English version

UPD1 2020.05.01 20:30 — callback_whitelist = profile_tasks . ansible. mitogen
UPD2 2020.05.03 16:34 — English version