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spurs
Flight Engineer
Flight Engineer
  • 435 Views

group_vars usage

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Hello, 

I was doing lab and saw the question that moving the variable files to the group_vars after creating the directory.

what does group_vars exactly do and when should I use?

+actually want to know more about host_vars as well

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anthonywongibm
Mission Specialist
Mission Specialist
  • 296 Views

That groups all variable to same directory, so that you no need to handle the variables in seperate yml files. Easiler to handle the variables.

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Ricardo
Flight Engineer Flight Engineer
Flight Engineer
  • 287 Views

Hi @spurs ,

The folders group_vars and host_vars are a way to organize the variables in a single place. As the name suggests, group_vars are for groups, and host_vars for hosts.

There are two ways to use them:

  1. Creating a file with the group/host name with your variables inside it.
  2. Creating a folder with the group/host name and dropping the files with the variables inside it. All files will be used

The files must be on YAML format and can have ".yml", ".yaml", ".json" extensions, or no extension at all.

Because there are several places we can define a variable, is important to observe the reading precedence that ansible utilizes. You can find more info here [1].

I hope this clarifies better.

Cheers
Ricardo

[1] https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html#variable-precedence-...

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bonnevil
Starfighter Starfighter
Starfighter
  • 222 Views

If you're trying to sort through the different group_vars and host_vars directories in the precedence list that @Ricardo posted:

"inventory group_vars" is the group_vars subdirectory in the same directory as your inventory file

"playbook group_vars" is the group_vars subdirectory in the same directory as your playbook file

And the same relationship is true for "inventory host_vars" and "playbook host_vars". 

If your inventory file and your playbook are in the same directory, as it is with many of our exercises, obviously the variables in the host_vars and group_vars subdirectories are set as both inventory host_vars and playbook host_vars. 

If you look at the precedence chart, this usually doesn't matter much because, for example, inventory host_vars are immediately below playbook host_vars in precedence.  It only matters if your inventory file and playbook file are in different directories and the group_vars and host_vars files have different settings in the different directories -- in that case, the group_vars and host_vars in the playbook's directory wins with one step higher precedence.

Host or group based variables actually set directly inside an inventory file have lower priority than any host_vars or group_vars settings.

Variables set in the vars section of a play in the playbook ("play vars") have higher precedence than all of these host-based variables.

 

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5 Replies
anthonywongibm
Mission Specialist
Mission Specialist
  • 297 Views

That groups all variable to same directory, so that you no need to handle the variables in seperate yml files. Easiler to handle the variables.

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spurs
Flight Engineer
Flight Engineer
  • 271 Views

Thanks anthony!

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Ricardo
Flight Engineer Flight Engineer
Flight Engineer
  • 288 Views

Hi @spurs ,

The folders group_vars and host_vars are a way to organize the variables in a single place. As the name suggests, group_vars are for groups, and host_vars for hosts.

There are two ways to use them:

  1. Creating a file with the group/host name with your variables inside it.
  2. Creating a folder with the group/host name and dropping the files with the variables inside it. All files will be used

The files must be on YAML format and can have ".yml", ".yaml", ".json" extensions, or no extension at all.

Because there are several places we can define a variable, is important to observe the reading precedence that ansible utilizes. You can find more info here [1].

I hope this clarifies better.

Cheers
Ricardo

[1] https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html#variable-precedence-...

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spurs
Flight Engineer
Flight Engineer
  • 271 Views

Thanks a lot, Ricardo, The other link about precedence was very helpful as well.

Cheers

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bonnevil
Starfighter Starfighter
Starfighter
  • 223 Views

If you're trying to sort through the different group_vars and host_vars directories in the precedence list that @Ricardo posted:

"inventory group_vars" is the group_vars subdirectory in the same directory as your inventory file

"playbook group_vars" is the group_vars subdirectory in the same directory as your playbook file

And the same relationship is true for "inventory host_vars" and "playbook host_vars". 

If your inventory file and your playbook are in the same directory, as it is with many of our exercises, obviously the variables in the host_vars and group_vars subdirectories are set as both inventory host_vars and playbook host_vars. 

If you look at the precedence chart, this usually doesn't matter much because, for example, inventory host_vars are immediately below playbook host_vars in precedence.  It only matters if your inventory file and playbook file are in different directories and the group_vars and host_vars files have different settings in the different directories -- in that case, the group_vars and host_vars in the playbook's directory wins with one step higher precedence.

Host or group based variables actually set directly inside an inventory file have lower priority than any host_vars or group_vars settings.

Variables set in the vars section of a play in the playbook ("play vars") have higher precedence than all of these host-based variables.

 

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