Ansible: approach to loop through a complex variable in order to access different layers under the same task - ansible

Question

What would be the correct approach to loop through a complex dictionary variable in an Ansible play in order to be able to call items from different layers of the variable in the same module/task?
The variable in question looks like this (but it could be any number of layers down, so far I only have about 3 layers down):
installation:
v10:
installs: yes
das_username: dasusr
das_group: dasadm
package_name: v10.tar.gz
binaries_folder: binaries
install_path: /opt/V10
instances:
inst1:
enabled: yes
username: inst1
group: dbiadm
port: 50000
databases:
jts:
name: 'JTS'
state: present
pagesize: 32768
rtc:
name: 'CCM'
state: absent
pagesize: 16384
rqm:
name: 'QM'
state: absent
pagesize: 32768
inst2:
enabled: no
username: inst2
group: dbiadm
port: 50005
databases:
warehouse:
name: 'DW'
state: present
pagesize: 32768
v9:
installs: no
instances:
inst3:
enabled: no
databases:
rqm:
name: 'RM'
state: absent
pagesize: 32768
lqe:
name: 'LQE'
state: absent
pagesize: 16384
Tasks include creating databases using the install_path (layer 1) and databases parameters (layer 3) under the same shell module or in a template.
For example (the task should look something like this) but with the correct method of looping:
- name: Creating the databases
become_user: "{{ item.0.instances.username }}"
shell: "./db2 create database {{ item.1.name }} using pagesize {{ item.1.pagesize }}"
args:
chdir: "{{ item.0.install_path }}/bin"
with_subelements:
- "{{ installation }}"
- instances.databases.clm
Thank you!

Answer 1

It's not a trivial feat to do such thing in ansible, becase loops in ansible are one-dimensional. There is a hackish way though, you can use nested includes with loop control. So let's say i put all of your variables inside vars.yml and have a following files:
playbook-nested.yml
- hosts: localhost
tasks:
- name: pass version forward
include: instances.yml v="{{ version_item }}"
with_items: "{{ installation }}"
loop_control:
loop_var: version_item
instances.yml
- name: Pass instance forward
include: databases.yml i={{ instance_item }}
with_items: "{{ installation[v].instances }}"
loop_control:
loop_var: instance_item
databases.yml
- name: echo command
debug: msg="./db2 create database {{ item.name }} using pagesize {{ item.pagesize }}"
with_items: "{{ installation[v].instances[i].databases.clm }}"
when: installation[v].instances[i].databases.clm is defined
So the output of command ansible-playbook playbook-nested.yml -e #vars.yml will be:
PLAY [localhost] ***************************************************************
TASK [setup] *******************************************************************
ok: [localhost]
TASK [pass version forward] ****************************************************
included: /home/user/instances.yml for localhost
included: /home/user/instances.yml for localhost
TASK [Pass instance forward] ***************************************************
included: /home/user/databases.yml for localhost
TASK [echo command] ************************************************************
ok: [localhost] => (item={u'state': u'absent', u'name': u'RQM', u'pagesize': 32768}) => {
"item": {
"name": "RQM",
"pagesize": 32768,
"state": "absent"
},
"msg": "./db2 create database RQM using pagesize 32768"
}
ok: [localhost] => (item={u'state': u'absent', u'name': u'LQE', u'pagesize': 16384}) => {
"item": {
"name": "LQE",
"pagesize": 16384,
"state": "absent"
},
"msg": "./db2 create database LQE using pagesize 16384"
}
TASK [Pass instance forward] ***************************************************
included: /home/user/databases.yml for localhost
included: /home/user/databases.yml for localhost
TASK [echo command] ************************************************************
ok: [localhost] => (item={u'state': u'present', u'name': u'JTS', u'pagesize': 32768}) => {
"item": {
"name": "JTS",
"pagesize": 32768,
"state": "present"
},
"msg": "./db2 create database JTS using pagesize 32768"
}
ok: [localhost] => (item={u'state': u'absent', u'name': u'CCM', u'pagesize': 16384}) => {
"item": {
"name": "CCM",
"pagesize": 16384,
"state": "absent"
},
"msg": "./db2 create database CCM using pagesize 16384"
}
ok: [localhost] => (item={u'state': u'absent', u'name': u'QM', u'pagesize': 32768}) => {
"item": {
"name": "QM",
"pagesize": 32768,
"state": "absent"
},
"msg": "./db2 create database QM using pagesize 32768"
}
TASK [echo command] ************************************************************
skipping: [localhost]
PLAY RECAP *********************************************************************
localhost : ok=8 changed=0 unreachable=0 failed=0
I'm not sure what does clm mean and do i have to loop over databases as well, but i think the concept is clear to you now.
You can also use the nested_loops on the lower level i guess.