ansible variables inside variables - ansible

Question

I'm trying to build a role which uses some variables from a file.
Though this variables also depend on some common variable which I want to define for all roles only one without copy&paste it to every single variable file.
Though I can't understand how I can do that. I'm talking about vars file only.
E.g. roles/dns/tasks/main.yml includes file for specific location:
- include_vars: ../vars/dns/domains_{{ location }}.yml
location is defined on role level. Inside this I'm trying to define settings for various dns names, e.g.:
domains: [
{
domain: "domain.com",
location: "america",
ip: "xx.xx.xx.xx",
ttl: 1800,
mx: "10 mail",
subdomains: [
{ name: "www", ip: "xx.xx.xx.xx"},
]
},
]
so here I have the same IP defined for each and every entry.
Is there a way to put all IPs into some global var file (e.g. group_vars/all/vars_file.yml ) and use it inside this role specific var file like this:
domains: [
{
domain: "domain.com",
location: "america",
ip: server.america.ip,
ttl: 1800,
mx: "10 mail",
subdomains: [
{ name: "www", ip: server.america.ip },
]
},
]
where server.america.ip is defined somewhere global?

Answer 1

Yes, that's possible. Variable files actually run through jinja as well, so you can have basic expressions and variables in variable files.
domains: [
{
domain: "domain.com",
location: "america",
ip: "{{ server.america.ip }}",
ttl: 1800,
mx: "10 mail",
subdomains: [
{ name: "www", ip: "{{ server.america.ip }}" },
]
},
]

Answer 2

You can include variables from role X, at beginning of tasks/main.yml of your role Y, for example.
If you have a common role, let's put location on this one, for example.
Only potential problem, is that you might need to use 'with_items' to call included variables.