if else syntax in ansible playbook

Question

I am new to Ansible and trying to understand what is wrong with my syntax.

My goal is that only one of the roles will be selected. I do not want to use 'when'.

Here is what I wrote (I am using Ansible v2.9.5):

- name: Install external DB for Cloudera Manager Server
  hosts: db_server
  roles:
 - {{% if (databases_type == "postgresql") %} role: postgresql {% else %} {% endif %}
   {% if (databases_type == "mysql") %} role: mariadb {% else %} {% endif %} 
   {% if (databases_type == "oracle") %} role: oracledb}

When I run the playbook I get a syntax error but it is not clear enough.

Thanks in advance.

Vladimir Botka · Accepted Answer · 2020-07-15T07:53:18.460

A simple dictionary might be a cleaner option. For example

shell> cat playbook.yml
- name: Install external DB for Cloudera Manager Server
  hosts: db_server
  vars:
    my_roles:
      postgresql: postgresql
      mysql: mariadb
      oracle: oracledb
  tasks:
    - include_role:
        name: "{{ my_roles[databases_type] }}"

Example

Let's create the roles

shell> cat roles/postgresql/tasks/main.yml
- debug:
    var: role_name

shell> cat roles/mariadb/tasks/main.yml
- debug:
    var: role_name

shell> cat roles/oracledb/tasks/main.yml
- debug:
    var: role_name

Next, let's create an inventory with three servers, group_vars with default databases_type and host_vars with the variables for two hosts test_01 and test_02. The third host test_03 will use the variables from group_vars.

shell> cat hosts
[db_server]
test_01
test_02
test_03

shell> cat group_vars/db_server 
databases_type: mysql

shell> cat host_vars/test_01 
databases_type: postgresql
shell> cat host_vars/test_02
databases_type: oracle

Then the playbook gives (abridged)

shell> ansible-playbook -i hosts playbook.yml 

PLAY [Install external DB for Cloudera Manager Server] *****************

TASK [include_role : {{ my_roles[databases_type] }}] *******************

TASK [postgresql : debug] **********************************************
ok: [test_01] => 
  role_name: postgresql

TASK [oracledb : debug] ************************************************
ok: [test_02] => 
  role_name: oracledb

TASK [mariadb : debug] *************************************************
ok: [test_03] => 
  role_name: mariadb

Thanks. For this I get an error: "databases_type is undefined". In my playbook databases_type in defined under group_vars/all — jrz, Jul 15 '20 at 07:11
Use `include_role`. The variable `databases_type` will be defined when the control-flow reaches `include_role`. I've added an example. The variable `databases_type` must be available before the name of the role is evaluated which is obviously not the case with `roles`. `import_role` won't work either for the same reason. — Vladimir Botka, Jul 15 '20 at 07:49

score 2 · Answer 2 · answered Jul 14 '20 at 17:48

I believe that this is what you are looking for. In the below example, fruit is the variable name. If fruit is equal to Apple then I like it else I do not like it. Let me know if you face any issue or you need more explanation on this.

If else syntax:

 - name: "[ If Else Example ]"
            command: "echo {{ 'I like it' if  fruit == 'Apple'  else 'I do not like it'}}"
            register: if_reg
          - debug:
                  msg: "{{ if_reg.stdout }}"

score 0 · Answer 3 · answered Jul 14 '20 at 15:07

0

It seems you have double curly bracket:

- {{% if ...

Try removing it to make single curly bracket:

e.g.

- {% if ...

also last line could remove ending curly bracket and put endif:

{% if (databases_type == "oracle") %} role: oracledb {% endif %}

answered Jul 14 '20 at 15:07

user1697575

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if else syntax in ansible playbook

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