ticktockhouse ticktockhouse - 4 months ago 102
YAML Question

Ansible - grab a key from a dictionary (but not in a loop)

Another question regarding dictionaries in Ansible!

For convenience, I have certain values for mysql databases held in dictionaries, which works fine to loop over using

with_dict
to create the DBs and DB users.

mysql_dbs:
db1:
user: db1user
pass: "jdhfksjdf"
accessible_from: localhost
db2:
user: db2user
pass: "npoaivrpon"
accessible_from: localhost


task:

- name: Configure mysql users
mysql_user: name={{ item.value.user }} password={{ item.value.pass }} host={{ item.value.accessible_from }} priv={{ item.key }}.*:ALL state=present
with_dict: "{{ mysql_dbs }}"


However, I would like to use the key from one of the dictionaries in another task, but I don't want to loop over the dictionaries, I would only like to use one at a time. How would I grab the key that describes the dictionary (sorry, not sure about terminology)?

problem task:

- name: Add the db1 schema
shell: mysql {{ item }} < /path/to/db1.sql
with_items: '{{ mysql_dbs[db1] }}'


Error in ansible run:

fatal: [myhost]: FAILED! => {"failed": true, "msg": "'item' is undefined"}


I'm willing to believe
with_items
isn't the best strategy here, but does anyone have any ideas what is the right one?

Thanks in advance, been stuck on this for a while now...

Answer

Given a nested dictionary...

mysql_dbs:
  db1:
    user: db1user
    pass: "jdhfksjdf"
    accessible_from: localhost
  db2:
    user: db2user
    pass: "npoaivrpon"
    accessible_from: localhost

You can either use dotted notation:

- debug:
    var: mysql_dbs.db1

Or you can use a more Python-esque syntax:

- debug:
    var: mysql_dbs['db1']

It looks like you tried to use an unholy hybrid:

mysql_dbs[db1]

In this case, you are trying to dereference a variable named db1, which presumably doesn't exist and would lead to a "variable is undefined" sort of error.

Update

Your question is unclear because in your example you have...

with_items: '{{ mysql_dbs[db1] }}'

...which looks like you are trying to do exactly what I have described here. If what you actually want to do is iterate over the keys of the mysql_dbs dictionary, remember that it is simply a Python dictionary and you have available all the standard dictionary methods, so:

- debug:
    msg: "key: {{ item }}"
  with_items: "{{ mysql_dbs.keys() }}"

The output of which would be:

TASK [debug] *******************************************************************
ok: [localhost] => (item=db1) => {
    "item": "db1", 
    "msg": "key: db1"
}
ok: [localhost] => (item=db2) => {
    "item": "db2", 
    "msg": "key: db2"
}