[HOSTVARS][MERGED] Unexpected behavior with merge variables of different host which are in several groups

[Baptiste Doublet]

Hi Everybody,

I have a problem that I can't resolve on my own.

I want to deploy an etcd cluster with postgresql on the same servers

I have three servers and this is my inventory file:

```

all:

children:

etcd_cluster: # recommendation: 3 or 5-7 nodes

hosts:

demo_postgres1:

vars:

etcd_ip: '***'

demo_postgres2:

vars:

etcd_ip: '***'

demo_postgres3:

vars:

etcd_ip: '***'

master:

hosts:

demo_postgres1:

vars:

postgres_ip: '***'

postgresql_exists: 'false'

replica:

hosts:

demo_postgres2:

vars:

postgres_ip: '***'

postgresql_exists: 'false'

demo_postgres3:

vars:

postgres_ip: '***'

postgresql_exists: 'false'

balancers:

hosts:

demo_haproxy1:

vars:

haproxy_ip: '***'

demo_haproxy2:

vars:

haproxy_ip: '***'

demo:

vars:

ansible_ssh_common_args: "-F ../../ssh_config/demo_config"

children:

balancers:

etcd_cluster:

postgres_cluster:

children:

master:

replica:

```

I have the demo_postgres[0-3] servers that run etcd and postgres. Just to prepare an external instance for etcd cluster, I have separated its in two distinct groups: etcd_cluster and postgres_cluster.

I have etcd_ip vars and postgres_ip vars respectively on these groups.

My problem is when I run my playbook with hosts: etcd_cluster and I print hostvars, I get the hostvars of postgres_cluster:

```

PLAY [etcd_cluster] ***************************************************************************************************************************************************************************

TASK [Gathering Facts] ************************************************************************************************************************************************************************
ok: [demo_postgres1]
ok: [demo_postgres3]
ok: [demo_postgres2]

TASK [Ansible | List all known variables and facts] *******************************************************************************************************************************************
ok: [demo_postgres1] => {
    "hostvars[inventory_hostname]['vars']": {
        "postgres_ip": "***",
        "postgresql_exists": "false"
    }
}
ok: [demo_postgres2] => {
    "hostvars[inventory_hostname]['vars']": {
        "postgres_ip": "***",
        "postgresql_exists": "false"
    }
}
ok: [demo_postgres3] => {
    "hostvars[inventory_hostname]['vars']": {
        "postgres_ip": "***",
        "postgresql_exists": "false"
    }
}

```

I didn't find any information about the merging of hostvars when the host is in multiple groups and when I have tested to remove the postgres_cluster group, I get the correct hostvars:

```

PLAY [etcd_cluster] ***************************************************************************************************************************************************************************

TASK [Gathering Facts] ************************************************************************************************************************************************************************
ok: [demo_postgres1]
ok: [demo_postgres3]
ok: [demo_postgres2]

TASK [Ansible | List all known variables and facts] *******************************************************************************************************************************************
ok: [demo_postgres1] => {
    "hostvars[inventory_hostname]['vars']": {
        "etcd_ip": "***"
    }
}
ok: [demo_postgres2] => {
    "hostvars[inventory_hostname]['vars']": {
        "etcd_ip": "***"
    }
}
ok: [demo_postgres3] => {
    "hostvars[inventory_hostname]['vars']": {
        "etcd_ip": "***"
    }
}

```

I would expect that my etcd_ip was merged with postgres_ip ? I can resolve this by adding the etcd_ip in postgres_cluster hostvars but I want to understand why merge is not working.

If you need more information, feel free to ask.

Best regards,

BDO

[Jean-Yves LENHOF]

Hi,

As I understand etc_ip and postgresql_ip are variable specific for each host, and so they should be in hosts parts of your inventory file (Here you are doing a mix).

postgresql_exists can be setup in a your postgresql group, but I'm not sure if it is really necessary to have it

See there for example : https://docs.ansible.com/ansible/latest/plugins/inventory/yaml.html

If you want further help, please provide your playbooks used for your outputs.

And for the record, no needs to use a playbook to list variables, command "ansible-inventory" can be used successfully for this

Regards,

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[Baptiste Doublet]

Hi,

thanks for your reply.

Yeah that's it. etcd_ip and postgresql_ip are in separate host. But I don't understand, there are already on the host part, aren't it ?

what is the syntax you think of ?

This is the playbook which should get the etcd_ip

```

- hosts: etcd_cluster

become: true

become_method: sudo

any_errors_fatal: true

gather_facts: true

vars_files:

- vars/main.yml

- vars/system.yml

- "vars/{{ ansible_os_family }}.yml"

tasks:

- meta: flush_handlers

- import_tasks: tasks/sysctl.yml

tags: [ sysctl, kernel ]

- import_tasks: tasks/timezone.yml

when: timezone is defined and timezone | length > 0

ignore_errors: yes

tags: [ timezone, configure ]

- import_tasks: tasks/ntp.yml

when: ntp_enabled is defined and ntp_enabled == "true"

ignore_errors: yes

tags: [ ntp, configure ]

- import_tasks: tasks/etcd.yml

when: dcs_exists == "false" and dcs_type == "etcd"

tags: [ etcd, etcd_cluster ]

```

[Stefan Hornburg (Racke)]

On 4/15/20 8:41 PM, Baptiste Doublet wrote:
> Hi,
>
> thanks for your reply.
>
> Yeah that's it. etcd_ip and postgresql_ip are in separate host. But I don't understand, there are already on the host
> part, aren't it ?
> what is the syntax you think of ?

Try to remove vars: from your inventory when you specify host variables, e.g.

etcd_cluster: # recommendation: 3 or 5-7 nodes
hosts:
demo_postgres1:

etcd_ip: '***'

Regards
Racke

> I have etcd_ip vars and postgres_ip varsrespectivelyon these groups.

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--
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Debian and Sympa administration. Provisioning with Ansible.

[Baptiste Doublet]

Hi,

That did the job:

etcd_cluster: # recommendation: 3 or 5-7 nodes
      hosts:
        demo_postgres1:

            etcd_ip: '***'

I don't know why I used vars, maybe because I read a lot of ansible documentation like How to build your inventory and that cursed my brain ^^

atlanta:
  hosts:
    host1:
    host2:
  vars:
    ntp_server: ntp.atlanta.example.com
    proxy: proxy.atlanta.example.com

Thanks again Racke !

Le mardi 14 avril 2020 11:39:36 UTC+2, Baptiste Doublet a écrit :

[Stefan Hornburg (Racke)]

On 4/17/20 4:54 PM, Baptiste Doublet wrote:
> Hi,
>
> That did the job:
> etcd_cluster: # recommendation: 3 or 5-7 nodes
>       hosts:
>         demo_postgres1:
>             etcd_ip: '***'
>
> I don't know why I used vars, maybe because I read a lot of ansible documentation like How to build your inventory and
> that cursed my brain ^^
>

While the documentation covers a lot of good thing, it doesn't note the differences between group variables (with vars:
) and host vars (without vars:).

In order to avoid confusion, you can use separate files for the host variables.

Regards
Racke

> I have etcd_ip vars and postgres_ip varsrespectivelyon these groups.

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> To unsubscribe from this group and stop receiving emails from it, send an email to
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> <https://groups.google.com/d/msgid/ansible-project/c455f9f0-ff4a-4d15-b7c1-d0f9ff06bc37%40googlegroups.com?utm_medium=email&utm_source=footer>.