In Ansible, how to combine variables from separate files into one array?

You can not do that. Variables will always override variables with the same name. The only thing you could do with this exact setup is to write your own vars plugin which reads those files and merges them into an array.

If you are open to change the structure of your apps definition you can use a hash and set your hash_behavior=merge. In each vars file then you'd have a definition like:

apps:
  app1:
    git_repo: https://github.com/philgyford/app1.git

apps:
  app2:
    git_repo: https://github.com/philgyford/app2.git

When Ansible loads both files it will merge it automatically together into:

apps:
  app1:
    git_repo: https://github.com/philgyford/app1.git
  app2:
    git_repo: https://github.com/philgyford/app2.git</pre>

But be advised that hash_behavior=merge fundamentally changes the default behavior of Ansible on a global level. Make sure all your roles do not have issues with this setting. The documentation mentions:

We generally recommend not using this setting unless you think you have an absolute need for it

If you still use Ansible 1 you could use one of my old plugins instead: include_vars_merged. Basically this adds the behavior of hash_behavior=merge to only a single task.

_{I have not yet looked into migrating this to Ansible 2 though and currently it looks like I won't have the need for it any longer.}

Well, you cannot directly build an array, but you can achieve the same effort with a dict.

Suppose you want to construct an array:

[{
    name: 'bob',
    age: 30
}, {
    name: 'alice',
    age: 35 
}]

You can put each element in a file like:

bob.yml

bob:
  name: bob
  age: 30

alice.yml

alice:
  name: alice
  age: 35

Place these files in the same dir (e.g. user), then use include_vars to load the whole dir:

- name: Include vars
  include_vars:
    name: users
    dir: user

This will give you a dict users:

users:
  alice:
    name: alice
    age: 35
  bob:
    name: bob
    age: 30

User the dict2items filter in ansible, you get the array you want

Since Ansible 2.2, the include_vars (link) module has been expanded quite a bit.

It's now possible to do something like:

- include_vars:
    name: 'apps'
    dir: '../vars'
    extensions:
      - 'yaml'
      - 'yml'

name is the key there. From the module page:

The name of a variable into which assign the included vars. If omitted (null) they will be made top level vars.

This allows you to convert:

vars/
    app1.yml
    app2.yml
    ...

app1.yml:

name: app1
git_repo: https://github.com/philgyford/app1.git
# ...

app2.yml:

name: app2
git_repo: https://github.com/philgyford/app2.git
# ...

Into...

apps:
  - name: app1
    git_repo: https://github.com/philgyford/app1.git
    # ...
  - name: app2
    git_repo: https://github.com/philgyford/app2.git
    # ...

Use attribute name and put the included variables into the dictionaries. Fit the name of the dictionaries to your needs. For example

    - name: Load var files
      include_vars:
        file: "{{ item }}"
        name: "incl_vars_{{ item|basename|splitext|first }}"
      with_fileglob:
        - vars/*.yml

Then, use the lookup plugin varnames (New in version 2.8.), find all dictionaries, and iterate the list. In the loop use the lookup plugin vars (New in version 2.5.) and create the list apps. For example

    - set_fact:
        apps: "{{ apps|default([]) + [lookup('vars', item)] }}"
      loop: "{{ query('varnames', '^incl_vars_(.*)$') }}"

gives

apps:
  - git_repo: https://github.com/philgyford/app2.git
    name: app2
  - git_repo: https://github.com/philgyford/app1.git
    name: app1

You can convert the list to a dictionary if you want to

    - set_fact:
        apps: "{{ dict(_keys|zip(apps)) }}"
      vars:
        _keys: "{{ apps|map(attribute='name')|list }}"

gives

apps:
  app1:
    git_repo: https://github.com/philgyford/app1.git
    name: app1
  app2:
    git_repo: https://github.com/philgyford/app2.git
    name: app2