Other host's host variables not available (for Zookeeper)

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1

I’m trying to build a playbook that will deploy and configure a Zookeeper cluster. For a cluster, Zookeeper requires that “You attribute the server id to each machine by creating a file named myid” [1]. The zoo.cfg needs to have the IP address and myid for all the hosts in the cluster.

So I’ve got this for my host list:

[zookeepers]
192.168.2.2 myid=1
192.168.2.3 myid=2
192.168.2.4 myid=3

My tasks:

2

Blair Zajac wrote:

I'm trying to build a playbook that will deploy and configure a Zookeeper
cluster. For a cluster, Zookeeper requires that "You attribute the server
id to each machine by creating a file named myid" [1]. The zoo.cfg needs
to have the IP address and myid for all the hosts in the cluster.

So I've got this for my host list:

[zookeepers]
192.168.2.2 myid=1
192.168.2.3 myid=2
192.168.2.4 myid=3

My tasks:

---
- name: install zookeeperd
  action: apt pkg=zookeeperd

- name: write zookeeper's myid
  action: template src=../templates/myid.j2 dest=/var/lib/zookeeper/myid
  notify:
    - restart zookeeper

- name: write zookeeper' zoo.cfg
  action: template src=../templates/zoo.cfg.j2
dest=/etc/zookeeper/conf/zoo.cfg backup=yes
  notify:
    - restart zookeeper

Here is myid.j2:
{{ myid }}

Here is zoo.cfg

# specify all zookeeper servers
# The fist port is used by followers to connect to the leader
# The second one is used for leader election
{% for host in groups['zookeepers'] %}
# server.{{ HOW TO GET myid HERE}}={{ host }}:2888:3888
{% endfor %}

This is exactly what hostvars is for. See
http://ansible.cc/docs/playbooks2.html#accessing-information-about-other-hosts
and then use {{ hostvars[host]['myid'] }}

Daniel

3

Have you tried, inside that loop, something like:

{{ hostvars[host]['myid'] }}

?

Note the hosts must have been talked to at least once previously in
the ansible run for that to be loaded for facts, inventory variables
should be immediately accessible.

4

Sweet, thanks for the quick reply, that works great!

I think the template doc section could be expanded to mention this, I may put together a patch for it.

Blair

[1] http://ansible.cc/docs/modules.html#template

5

Thanks to Daniel's note, that works great.

To flush out the docs at http://ansible.cc/docs/modules.html#template, besides the following keys, are there any others? I didn't find the other examples that showed this.

   groups
   hostvars
   ansible_managed
   template_host
   template_uid
   template_path
   template_fullpath
   template_run_date

Blair

6

$ansible_hostname
$ansible_hostname_short (does not have FQDN if there was one on the above)

7

Michael DeHaan wrote:

$ansible_hostname
$ansible_hostname_short (does not have FQDN if there was one on the
above)

No, those are facts from the setup module. inventory_hostname and
inventory_hostname_short are special though.

In addition, there is group_names. These are all documented in the section
I linked earlier.

The template_* vars should indeed be documented in the template module
documentation, as they are only available for templates.

Daniel

8

General concept correct, actual letters not so much :slight_smile: