Proper way to concatenate variable strings

Question

I need to create new variable from contents of other variables. Currently I\'m using something like this:

- command: echo \"{{ var1 }}-{{ var2 }}-{{ var3 }}\"
           


        

Answer 1

Good question. But I think there is no good answer which fits your criteria. The best I can think of is to use an extra vars file.

A task like this:

- include_vars: concat.yml

And in concat.yml you have your definition:

newvar: "{{ var1 }}-{{ var2 }}-{{ var3 }}"

Answer 2

Since strings are lists of characters in Python, we can concatenate strings the same way we concatenate lists (with the + sign):

{{ var1 + '-' + var2 + '-' + var3 }}

If you want to pipe the resulting string to some filter, make sure you enclose the bits in parentheses:

e.g. To concatenate our 3 vars, and get a sha512 hash:

{{ (var1 + var2 + var3) | hash('sha512') }}

Note: this works on Ansible 2.3. I haven't tested it on earlier versions.

Answer 3

As simple as joining lists in python itself.

ansible -m debug -a msg="{{ '-'.join(('list', 'joined', 'together')) }}" localhost

---

localhost | SUCCESS => {
  "msg": "list-joined-together" }

---

Works the same way using variables:

ansible -m debug -a msg="{{ '-'.join((var1, var2, var3)) }}" localhost