This article from Ansible.com shows how you can iterate over a group inside of a template file: https://support.ansible.com/hc/en-us/articles/201957887-How-to-loop-over-a-list-of-hosts-in-a-group-inside-of-a-template-
It shows the following code:
{% for host in groups['db_servers'] %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}
It works beautifully, but the servers I want to iterate over are defined by being in multiple groups. So imagine that I want to iterate over all of the servers that are in BOTH the db_servers and qa groups. How can I do this?
I tried to specify the intersection of the group in the same manner I do in my playbook, but that doesn't work. So, when I try:
{% for host in groups['db_servers:&qa'] %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}
I get the following error:
fatal: [54.173.247.115] => {'msg': "AnsibleUndefinedVariable: One or more undefined variables: 'dict object' has no attribute 'db_servers:&qa'", 'failed': True}
Any suggestions on how to iterate over multiple groups in a template file?
Ansible has the intersect filter. See Set Theory Filters.
{% for host in groups['db_servers'] | intersect(groups['qa']) %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}
You could wrap your loop in another for the two server groups:
{% for svrs in ['db_servers', 'qa'] %}
{% for host in groups[svrs] %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}
{% endfor %}
Related
I have a template named foo.yml.j2 used in an Ansible task to generate a foo.yml file:
{% for host in ansible_play_hosts_all %}
{{ host }},
{% endfor %}
Everything works fine except I need something like the following statement: For every host in ansible_play_hosts_all except for host==bar do this or that.
Is this achievable or the only way to do this is to categorize my hosts in different groups and use ansible_play_hosts_group?
You can use the reject filter to take your host out of the list so that it is not part of your loop:
{% for host in ansible_play_hosts_all | reject('==', 'bar') %}
{{ host }},
{% endfor %}
There are more options. The trivial one is using the condition in Jinja
{% for host in ansible_play_hosts_all %}
{% if host != 'bar' %}
{{ host }},
{% endif %}
{% endfor %}
Fit the format to your needs.
Example of a complete playbook for testing
- hosts: host_1,host_2,host_3
gather_facts: false
tasks:
- debug:
msg: |
{% for host in ansible_play_hosts_all %}
{% if host != 'host_2' %}
{{ host }},
{% endif %}
{% endfor %}
run_once: true
gives (abridged)
msg: |-
host_1,
host_3,
The next option is to remove blacklisted hosts from the loop, e.g.
blacklist: [host_2]
The template below gives the same result
{% for host in ansible_play_hosts_all|difference(blacklist) %}
{{ host }},
{% endfor %}
My template like as blow
{% if hostvars[inventory_hostname].local_zk_server_id is defined %}
zookeeperServers={% for host in {{ groups[{{ target_hosts }}] %}}
"{{ hostvars[host].inventory_hostname }}:2181,"
{% endfor %}
{% endif %}
output ishost1:2181,host2:2181,host3:2181,
How to trim last comma
There are several possible gotchas in your above template regarding variables access. Moreover, rather than trimming the last character in your string, the best solution is probably not to write it. Here is a better solution IMO in my below example fixing all the problems I'm referring to:
{% set zookeeperServers=[] %}
{% if hostvars[inventory_hostname].local_zk_server_id is defined %}
{% for host in groups[target_hosts] %}
{% zookeeperServers.append(hostvars[host].inventory_hostname + ":2181") %}
{% endfor %}
zookeeperServers="{{ zookeeperServers | join(',') }}"
{% endif %}
I know that it is possible to loop over lists in a Jinja2 template like this:
{% for host in vars['play_hosts'] %}
"{{ host }}"{% if not loop.last %},{% endif %}
{% endfor %}
(Example stolen from this question.)
How can I use AWS tag based values like "the IPs of all hosts with value 'dev' in tag 'Environment'" instead of vars['play_hosts']?
I found out myself that it is only a matter of using the right group. All ec2 instances with the same tag can be found in a group and can be addressed by using e.g. groups['tag_Environment_dev']. So the example from the question would look like this:
{% for host in groups['tag_Environment_dev'] %}
"{{ host }}"{% if not loop.last %},{% endif %}
{% endfor %}
I have the following loop in a template:
{% for host in groups['dbnodes'] %}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}
the issue is that it gives the output in list of ip's and I need it in comma separated value. Any idea how to achieve that?
the answer I get look like this:
10.0.0.190
10.0.0.117
10.0.0.151
but I need it like this:
10.0.0.190,10.0.0.117,10.0.0.151
A quick fix to your Jinja2 template:
{% for host in groups['dbnodes'] -%}
{{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}{% if not loop.last %},{% endif %}
{%- endfor %}
I need to iterate over all hosts and generate config file for hosts that are not contained in group somegroup:
{% for host in groups.all if host not in groups['somegroup'] %}
But if somegroup does not exist, it fails (argument of type 'StrictUndefined' is not iterable).
How do I write this correctly to avoid two different for cycles:
{% if groups['somegroup'] is defined %}
{% for host in groups.all if host not in groups['somegroup'] %}
...
{% endfor %}
{% else %}
{% for host in groups.all %}
...
{% endfor %}
{% endif %}
I think you're looking for the default filter:
{% for host in groups.all if host not in groups['somegroup'] | default([]) %}