How to use hostvars in template

[Piet83]

Hello,

Is it possible to use variables defined in a ansible host file for a template? Lets say this is the host file:

[webservers]
server1   city=amsterdam
server2   city=london

[databaseserver]
server3   city=amsterdam
server4   city=london

How can I use for instance the ip address of server3 which is in group databaseservers in amsterdam?  Is this possible? I would like to use this to fill iptables with ip addresses depending on group and city.


Regards,

Peter

[Brian Coca]

just do  {{ city }}​, if it is the 'current host', to access vars of other hosts {{ hostvars['server3'].city }}

[Piet83]

Ok but what if I don't know the server name but only that it is an database server in amsterdam?

Something like this, but then with the right syntax?

{{ groups["databaseserver"] | {{ hostvars["amsterdam"] }} | {{ ansible_eth0.ipv4.address }} }} 

Op dinsdag 29 juli 2014 14:23:04 UTC+2 schreef Brian Coca:

[Michael DeHaan]

The above imaginary syntax will not work, but this will :)  The groups array contains the names of each host in each group, and this picks out the first one in inventory order.

{{ hostvars[groups['databaseserver'][0]].ansible_eth0.ipv4.address }}




If using a template file versus inline in the playbook, I'd do this:

{# set db_head_node = groups['databaseserver'][0] #}

{{ hostvars[db_head_node].blarg }}

for readability purposes

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[Piet83]

Thank you Michael for the right syntax :)

Is it also possible to select one host in the goup array based on a city defined as variable for a particular host? In other words, I don't know on what position in the array the servername is I need. I only know it is in group databaseserver and that it has amterdam defined as variable city.

By the way if I try this in a template:

{{ hostvars[groups['databaseserver'][0]].ansible_eth0.ipv4.address }}


I get the following error running a playbook with the above in a template:


fatal: [localhost] => {'msg': "One or more undefined variables: 'dict' object has no attribute 'ansible_eth0'", 'failed': True}
fatal: [localhost] => {'msg': "One or more undefined variables: 'dict' object has no attribute 'ansible_eth0'", 'failed': True}

FATAL: all hosts have already failed -- aborting

Op dinsdag 29 juli 2014 17:07:57 UTC+2 schreef Michael DeHaan:

[Michael DeHaan]

I would use group_by to create a dynamic group first in a prior play, like so:

- hosts: webservers

  tasks:

     - group_by: name=webserver-{{ city | default('no_city') }}

And then you could use, in the template, replace the groupname 'webserver' with 'webserver-amsterdam' like so:

groups['webserver-amsterdam'][0]

to select the first one.

Others may prefer deep Jinja2 magic, but I'd find that more readable.   You can also use the dynamic group for other types of management in Ansible:

- hosts: webservers-amsterdam

  tasks:

     - yum: name=foo state=latest

etc

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/1cfae46f-eeea-4936-9cfe-1b9313c9a45f%40googlegroups.com.

[Piet83]

When I use the following in my playbook:
 
group_by: name=webservers-{{ city | default('no_city')}}

I get this error when running:

TASK: [group_by name=webservers-amsterdam] ****************************************
fatal: [ansible-test] => 'key' is a required argument.

ansible-test is my target host.

What am I doning wrong?


Op woensdag 30 juli 2014 14:15:43 UTC+2 schreef Michael DeHaan:

[Lucas, Sascha]

Hi,

> fatal: [ansible-test] => 'key' is a required argument.

group_by needs key=webservers-{{ city | default('no_city')}}, not name=...

HTH, Sascha.

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[Michael DeHaan]

Yep, typo on my part.

I can't keep 100% of this program in my head but only 97.2% :)

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[Piet83]

Thank you both!

May I ask an other question about hostvars in templates:

When I use the follwing i a playbook everything goes well:

The variable target is provided by the --extra-vars flag on the command line and mysqluserpass is defined in /etc/ansible/host_vars/ansible-test and encrypted with ansible-vault

{{ hostvars[{{target}}]['mysqluserpass'] }}


So when I use the above in a playbook it fills in the mysqluserpass nicely but when using this in a template to put the the mysql credentials in a file somewhere on the target machine it gives an syntax error:

fatal: [ansible-test] => {'msg': "file: /etc/ansible/templates/CREDS.j2, line number: 2, error: expected token 'colon', got '}'", 'failed': True}
fatal: [ansible-test] => {'msg': "file: /etc/ansible/templates/CREDS.j2, line number: 2, error: expected token 'colon', got '}'", 'failed': True}

FATAL: all hosts have already failed -- aborting

I've also tried: {{ hostvars[inventory_hostname]['mysqluserpass'] }} but no results.






Op donderdag 31 juli 2014 22:59:08 UTC+2 schreef Michael DeHaan:

[Michael DeHaan]

When using Jinja2 expressions it is not valid to use {{ }} around a variable inside another expression.

You had:

{{ hostvars[{{target}}]['mysqluserpass'] }}

You need

{{ hostvars[target]['mysqluserpass'] }}

Which also, thankfully, is easier to read too.

Can also be written

{{ hostvars[target].mysqluserpass }}

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/bc8dc0f8-9f85-44d7-86c1-b2ad4490c960%40googlegroups.com.

[Piet83]

Thank you Michael,

Only if I try both options you suggested I get i both cases:

fatal: [ansible-test] => {'msg': "One or more undefined variables: 'dict' object has no attribute 'mysqluserpass'", 'failed': True}
fatal: [ansible-test] => {'msg': "One or more undefined variables: 'dict' object has no attribute 'mysqluserpass'", 'failed': True}

It looks like it does not pick up the variables defined in my /etc/ansible/host_vars/ansible-test file.

Op vrijdag 1 augustus 2014 15:13:27 UTC+2 schreef Michael DeHaan:

[Michael DeHaan]

Can we see the host_vars file contents?

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/aa43b248-362c-44e2-bc3f-48143cbd259a%40googlegroups.com.

[Piet83]

Of course:

ansible-vault edit /etc/ansible/host_vars/ansible-test

---
mysqlrootpass: XXXXXXXXXXXXXXXXXX
mysqluserpass: XXXXXXXXXXXXXXXXXX

Op vrijdag 1 augustus 2014 16:30:43 UTC+2 schreef Michael DeHaan:

[Michael DeHaan]

My thought might be you are running things with an inventory file that is not in /etc/ansible, so it's looking for a host_vars directory beside that inventory file.

Other than that I don't know what might be up...

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[Piet83]

You are right Michael! We had /etc/ansible/production/hosts and /etc/ansible/staging/hosts. I've changed this to /etc/ansible/production and /etc/ansible/staging files.

Thank you very much!

Op vrijdag 1 augustus 2014 21:26:58 UTC+2 schreef Michael DeHaan: