How to override nested variables?

[Eric Chaves]

Hi folks,

I created a role with default variables using a nested syntax and not I'd like to override just a few of those attributes in the playbook, but whenever I do it I end up redefining the entire variable na loosing the defaults for the non overrided values.

For example, in role/mysql/defaults/main.yml:

---

  mysql:

      address: 127.0.0.1

      admin: admin

      password: 12345

Then in the my_server.yml:

---

- hosts: myserver

- roles:

  - mysql

- vars:

    mysql:

       password: abcdef

but once I do this mysql.address and mysql.admin become undefined. I have tried the mysql[address] syntax but it didn't work.

Is it possible to override just a few set of nested attributes?

Thanks for the help,

Eric

[Kahlil Hodgson]

There is a variable merging setting, but I prefer being explicit about
having a complex variable, parts of which can be overridden (rather
than magically "doing the right thing").

---
- hosts: myserver
- roles:
- mysql
- vars:

mysql_password: abcdef
- tasks:
- debug: msg="{{ mysql_password | default(mysql.password) }}"

This way it is clear that the password could have come from two
different places.

Hope this helps.

K


Kahlil (Kal) Hodgson GPG: C9A02289
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[Eric Chaves]

Hi Kahil,

Thanks for the suggestion, but the problem remains. You haven't override the default value, but instead declared a second flat variable. The problem with this approach is that if do this for every paramet I'll double the number of used variables. Also I will have to "flatten" them all which in practice would be easier to just flatten the defaults.

But I do wish to have the nested syntax because some of my variables become very confusing when flattening and I also found it better for organization and clarity in the yml.

Still hoping to find a way to do it.

Cheers,

--

Eric Chaves

(11) 98139-9880

2013/12/1 Kahlil Hodgson <kahlil....@dealmax.com.au>

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[Michael DeHaan]

"I created a role with default variables using a nested syntax and not I'd like to override just a few of those attributes in the playbook"

There is no problem in doing this.

You can use parameterized roles, include a variable file, use set_fact, or all sorts of things.

Now what you are asking is something different -- you should change the hash merge behavior in ansible.cfg.

Michael DeHaan <mic...@ansibleworks.com>
CTO, AnsibleWorks, Inc.
http://www.ansibleworks.com/

[Eric Chaves]

Michael, after reading the ansible.cfg documentation page, I found the parameter you mentioned, together with an warning against it. Since I value the experience from everyone here more than mine, would you care to explain why merging the hashes could be such bad idea?

Thanks again.

ps.: not trying to raise a flame, just like to hear about it.

--

Eric Chaves

(11) 98139-9880

2013/12/1 Michael DeHaan <mic...@ansibleworks.com>

[Serge van Ginderachter]

On 2 December 2013 02:32, Eric Chaves <er...@craftti.com.br> wrote:

after reading the ansible.cfg documentation page, I found the parameter you mentioned, together with an warning against it. Since I value the experience from everyone here more than mine, would you care to explain why merging the hashes could be such bad idea?

​I'm not sure which warning that is, but I can confirm you I have been using the merge functionality for a long time, and do not experience any problems with it.

Of course you have to remember or take into account where you define (different parts of) those hashes, ​and understand the possible implications.

Serge

[Michael DeHaan]

The config documentation was suggesting that most people leave it in the standard mode to make sure everybody's writing playbooks the same way.

That was it.

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[Eric Chaves]

Great! Thanks all for the inputs and help!

--

Eric Chaves

(11) 98139-9880

2013/12/2 Michael DeHaan <mic...@ansibleworks.com>

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