# Adding hosts to groups from the (yaml) host definition **URL:** \ **Category:** Ansible Project\ **Created:** [July 11, 2012, 9:47am UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661 "2012-07-11T09:47:37Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Dag\_Wieers](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@Dag\_Wieers](https://forum.ansible.com/u/Dag_Wieers)\ **Post date:** [July 11, 2012, 9:47am UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/1 "2012-07-11T09:47:37Z")
Hi, There is a need to have multiple groups where it is expected that each system belongs exactly to one group (of a certain set). For example, if you have 3 environments (prod, qa and dev) each system should be in only one of those 3. On the other hand, we may want to run a (set of) playbooks on a certain set of system (e.g. the production systems). Is there a way to set such groups from the host definition, so that we do not have to maintain lists of host (per set of groups), e.g. - system01    groups: [linux, prod, infra, distserver] where the groups would be resp. the os-group, the environment-group, the application-group and the servertype-group. The reason for having a separate group for the os is because we want to match certain plays based on a group (I don't think this is possible based on facts ?)    os-group consists of: linux, aix, solaris    environment-group consists of: prod, qa, dev    application-group consists of: about 120 different codes    servertype-group consists of: distserver, dbserver, webserver, custom The examples in the documentation expects one to keep seperate lists of hosts per group which is impossible to maintain properly. ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [July 11, 2012, 12:23pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/2 "2012-07-11T12:23:55Z")
> Hi, > > There is a need to have multiple groups where it is expected that each > system belongs exactly to one group (of a certain set). For example, if > you have 3 environments (prod, qa and dev) each system should be in only > one of those 3. > > On the other hand, we may want to run a (set of) playbooks on a certain > set of system (e.g. the production systems). > > Is there a way to set such groups from the host definition, so that we do > not have to maintain lists of host (per set of groups), e.g. > - system01 > groups: [linux, prod, infra, distserver] no, the parser is group first in terms of syntax. I don't like the idea of that being ambitious and supporting both, but you could definitely write an external inventory script to return the data however you like (feed a chmod +x script to ansible's -i). > where the groups would be resp. the os-group, the environment-group, the > application-group and the servertype-group. The reason for having a > separate group for the os is because we want to match certain plays based > on a group (I don't think this is possible based on facts ?) > > os-group consists of: linux, aix, solaris > environment-group consists of: prod, qa, dev > application-group consists of: about 120 different codes > servertype-group consists of: distserver, dbserver, webserver, custom Yep, sounds like you may want to write your own inventory script to read them in how you wish to define them. ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [July 11, 2012, 12:35pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/3 "2012-07-11T12:35:41Z")
One thing I should also add is that for users with clear differences between environments (stage, production, QA, etc) -- it is easy to maintain multiple inventory files. This prevents addressing production when you want to talk to stage. ansible -i /etc/ansible/stage\_hosts /path/to/playbooks/some\_playbook\_affecting\_stage.yml In other words, I would not want to keep all my application servers for QA defined with my production ones in the same file, and it's not required that you do. ---
**Author:** ![Dag\_Wieers](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@Dag\_Wieers](https://forum.ansible.com/u/Dag_Wieers)\ **Post date:** [July 11, 2012, 8:26pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/4 "2012-07-11T20:26:21Z")
But how would one reuse the same definitions for the groups ? A webserver in production should have the same variables as a webserver in QA. But having different hosts files for each would require one to duplicate those definitions. Or I miss something 🙂 ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [July 11, 2012, 8:37pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/5 "2012-07-11T20:37:43Z")
> > One thing I should also add is that for users with clear differences > > between environments (stage, production, QA, etc) – it is easy to > > maintain multiple inventory files. > > > > This prevents addressing production when you want to talk to stage. > > > > ansible -i /etc/ansible/stage\_hosts /path/to/playbooks/some\_playbook\_affecting\_stage.yml > > > > In other words, I would not want to keep all my application servers for > > QA defined with my production ones in the same file, and it’s not > > required that you do. > > But how would one reuse the same definitions for the groups ? A webserver > in production should have the same variables as a webserver in QA. But > having different hosts files for each would require one to duplicate those > definitions. Or I miss something 🙂 Stick the variables in your playbook. Playbooks are all about telling what particular groups of systems should behave like. I generally see inventory variables as for being for things about IP addresses that are location specific. - hosts: webservers vars: - … And you could actually use that same playbook between different inventory files if you wanted. If you needed to assign environment specific vars, you could do something (I think) like: [groupname:vars] x=2 y=3 z=4 Assigning the environment specific vars in the inventory file, using the group. ---
**Author:** ![Dag\_Wieers](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@Dag\_Wieers](https://forum.ansible.com/u/Dag_Wieers)\ **Post date:** [July 12, 2012, 2:10pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/6 "2012-07-12T14:10:11Z")
As to not being accused of asking for more ponies, here's the pull-request 😉      [https://github.com/ansible/ansible/pull/585](https://github.com/ansible/ansible/pull/585) ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [November 20, 2012, 1:56pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/7 "2012-11-20T13:56:06Z")
You can use YAML inventory if you really want to with this: [https://github.com/ansible/ansible/blob/devel/plugins/inventory/yaml.py](https://github.com/ansible/ansible/blob/devel/plugins/inventory/yaml.py) just use this as your inventory file by chmod +x'ing it host\_vars seeing it only sets vars (not groups) won't do what you want. ---
**Author:** ![Todd\_Wells](https://avatars.discourse-cdn.com/v4/letter/t/e9bcb4/32.png) [@Todd\_Wells](https://forum.ansible.com/u/Todd_Wells)\ **Post date:** [November 20, 2012, 9:30pm UTC](https://forum.ansible.com/t/adding-hosts-to-groups-from-the-yaml-host-definition/11661/8 "2012-11-20T21:30:17Z")
Thanks, yaml inventory now works, but the defined methods in the yaml.py file for defining groups under a host or in format do not appear to work with this file. twells@twlaptop:/etc/ansible$ ./hosts -l {“ungrouped”: [“localhost”, “system01”], “prod”: [“myhost1”, “myhost2”]} twells@twlaptop:/etc/ansible$ cat hosts.yml - host: localhost vars: - myvar: value - myvbr: vblue groups: - mygroup1 - mygroup2 - group: prod vars: - groupvar: value hosts: - myhost1 - myhost2 - host: system01 groups: [linux, production, dbserver]