====== - Ansible guide ======

===== - Best practices =====
==== - Using variable ====
2 types of variables: 
  * playbook parameters: define how the playbook behaves, i.e., 
    * what roles to run for each hosts --> These variables seem to be host-vars 
    * role configuration --> this should be avoided. Role related variables see the 2nd type vars.
  * Role variables: mostly should store data so the role can be reused with data for each playbook. E.g., role to set iptables rules taking rules parameters from variables.
    * How to change role behavior though?

==== - On the web ====
  * https://steampunk.si/blog/ansible-role-argument-specification/
    * https://sensu.github.io/sensu-go-ansible/roles/install.html
    * https://github.com/sensu/sensu-go-ansible/tree/master/roles/install


===== - Tips&Tricks =====
Display facts from all hosts and store them indexed by hostname at /tmp/facts.
     
     ansible -i inventory workers -m gather_facts --tree /tmp/facts |less
     
List tags and tasks

     ansible-playbook -i inventory --extra-vars "variable_hosts=k8s-02" install_k8s_playbook.yml --tags k8s --skip-tags masters,install --list-tasks -vvvv
     ansible-playbook -i inventory --extra-vars "variable_hosts=k8s-02" install_k8s_playbook.yml --tags k8s --skip-tags masters,install --list-tags -vvvv
     
===== - Troubleshooting =====
  * https://www.puzzle.ch/de/blog/articles/2020/01/22/10-dinge-ueber-ansible-die-du-vielleicht-noch-nicht-kanntest
==== - Tasks of included task not shown in task list ====

When using dynamic includes, it is important to keep these limitations in mind:
  - You cannot use notify to trigger a handler name which comes from a dynamic include.
  - You cannot use --start-at-task to begin execution at a task inside a dynamic include.
  - Tags which only exist inside a dynamic include will not show up in –list-tags output.
  - Tasks which only exist inside a dynamic include will not show up in –list-tasks output.
==== - Fact not defined for included tasks.yml ====
Problem:

<code>
  1 ---
  2 # tasks file for install
  3 - name: debug k8s.install undef fact
  4   debug:
  5     msg:
  6       - "role_path: {{ role_path }}"
  7       - "undef? ansible_pkg_mgr: {{ ansible_pkg_mgr }}"
  8
  9 - name : setup package repo
 10   import_tasks: repositories.yml
 11   tags: [install]
 12   when: ansible_facts.os_family != "Windows"
 13   # error: undef ansible_pkg_mgr
 14
 15         #- name: install k8s packages
 16         #  import_tasks: packages.yml
 17         #  tags: [install]
 18         #
main.yml   :b9[yaml] 6,31 All  1 

---
  2 #k8s-cluster-ansible/roles/k8s/roles/install/tasks/repositories.yml
  3
  4 - name: package repositories for "{{ ansible_pkg_mgr }}"
  5   import_tasks: "{{ ansible_pkg_mgr }}/repos.yml"
  6
~                                                                                                                                                                                                          ~                 
</code>

Solution:

Variables in task name not resolved for import_tasks. Must use include_tasks. Use apply.tags to recursively set tags.
     include_tasks: task_name
     tags: [always, or, t,a,g] <-- needed for the include task to be executed.     
       args:
         apply:
           tags: [t,a,g]
           become: yes

  * https://serverfault.com/questions/1023392/use-ansible-include-tasks-with-tags-on-the-sub-tasks          
==== - Variable in included task name ====

include_tasks: "{{ ansible_pkg_mgr }}/repos.yml" # variable in task name not resolved for import_tasks. Must use include_tasks. Use apply.tags to recursively set tags.

In this case may be use when to check the variable then select file name to be **imported**.

==== - Include_vars puts variable in ansible_facts ====

var.yml
<code>
  1 ---
  2 # Varfile to configure k8s installion using variables 
  3 #k8s_customize: # Customized k8s setup 
  4   network_plugin: "cilium"  
  5   ingress: "traefik" 
  6   dashboard: "dashboard"
  7   apps:  
  8     - "mosquitto"  
</code>

Using name, the name is also the variable containing file content. If not, file content are added directly to ansible_facts.

<code>

10     - include_vars:                                                                                                                                                                   11         file: "{{ playbook_dir }}/config.yml"                                
12         name: k8s_customize # create ansible_facts.k8s_customize   

TASK [include_vars] **********************************************************************************************************************************                  task path: /mnt/c/Users/Thuy Dang/Workspace/00_current/iiot/k8s-cluster-ansible/k8s-master-playbook.yml:10                                                                                     ok: [master] => {
    "ansible_facts": {                                                                                                                                                                                 "k8s_customize": {
            "apps": "mosquitto",
            "dashboard": "dashboard",
            "ingress": "traefik",
            "network_plugin": "cilium"
        }
    },
    "ansible_included_var_files": [
        "/mnt/c/Users/Thuy Dang/Workspace/00_current/iiot/k8s-cluster-ansible/config.yml"                                                                                                          ],
    "changed": false
}
</code>

==== - Inspect networks ====
  * https://www.digitalocean.com/community/tutorials/how-to-inspect-kubernetes-networking
  *