I used to use “hosts” property, in ansible playbook, dinamically for example:
hosts: ${$jobprofile.hosts}
where $jobprofile was an external variable that allow me to change hosts based on profile.
Since last 1.4 version, my previous playbook doesn’t works any more.
Have you some suggestion to do an EVAL into a playbook?
Thanks
Giorgio
Yeah this is a very outdated usage of legacy variables, and a bit of an anti-pattern whenever you want to define a variable by a variable name. (There’s a reason even Perl tries to discourage this, and that’s Perl).
I don’t know where you are defining “jobprofile”, but can we step back and talk about the use case?
Public service announcement, variables look like this:
foo: “{{ bar }}”
And if you want to get at a variable by name that is scoped to a host, you can do so if you want – which you won’t need often – like so:
{{ hostvars[inventory_hostname][fact_name] }}
This doesn’t of course apply to the host specifier – we haven’t even got to figure out what host we’ve talked to yet, hence I’m wanting to understand more.
This seems like a case better suited to seperate inventory files, or the case of a dynamic inventory script, the dynamic inventory script responding to an environment variable.
Hi Michael,
thanks for you response and for this awesome tool!
We’re using it for deployment jobs, as post-build of jenkins jobs, and we’re trying to do something like this:
-------------- job playbook ---------------
hosts: $vars[$prof][host]
tasks:
Hi Michael,
We are also using double evaluation in many places - mostly to not repeat definitions of the same variable
Example 1
user.yml - user uid values
userA: 800
userB: 801
main.yml - role variables
user: userA
user_uid: ${${user}} # will be resolved to 800
Example 2
type1_data:
var1: value1
var2: value1
type2_data:
var1: value2
var2: value2
type_data: ${${type}_data}
type_var1: ${type_data.var1}
type_var2: ${type_data.var2}
By overriding single variable we get different plays (all var blocks can be defined in role and block selection can go to single var in vars_files)
This also allows command line override with -e option by passing just one key=value.
What will be the appropriate way to use those after old syntax removed?
I feel like I’ve answered this a lot in the last 2 days, see the archives and we can add an entry in the FAQ.
– Michael
Though I couldn’t find anything related within past days - I just found solution to my problem using following vars 
users:
userA: 800
user: userA
user_uid: “{{ users[user] }}”
data:
type1:
key: value1
type2:
key: value2
type: type1
type_key: “{{ data[type].key }}”
Thanks
Dmitry you’re a f***** genius!!
Michael, please add Dimitry example in variables website documentation page… many users will appreciate!
Thanks guys!
Giorgio
I second Giorgio. Dmitry, you’re a lifesaver 
Dmitry, this is the solution to the ultimate problem I’ve been having. Thanks!!!
Dmitry,
You really saved my day !!!