Ansible change all dict key values only by filters

Question

I have an ansible dict like

ports:
  webui: 7200
  webadmin: 7209
  core_api: 7201
  stock_api: 7204
  import_export: 7207

And i want to transform all keys in it, like

ports:
  staging-webui: 7200
  staging-webadmin: 7209
  staging-core_api: 7201
  staging-stock_api: 7204
  staging-import_export: 7207

I do that in 'vars' section, so i can't use 'set_fact' with 'with_items' to iterate over dict. Is it possible to it only by filters?

I found working answer,

env: staging # comes from outside

regex_env: "\"key\": \"{{ env }}-\\1\""
app_upstreams: "{{ ports | dict2items | map('to_json') | map('regex_replace', '\"key\":\\s\"(.*)\"', lookup('vars', 'regex_env')) | map('from_json') }}"

but it looks really ugly, is there more good-looking solution?

Answer 1

For example, the playbook below

- hosts: localhost
  vars:
    env: staging_
    ports:
      webui: 7200
      webadmin: 7209
      core_api: 7201
      stock_api: 7204
      import_export: 7207
    env_ports_keys: "{{ [env]|product(ports.keys()|list)|map('join') }}"
    env_ports_vals: "{{ ports.values()|list }}"
    env_ports: "{{ dict(env_ports_keys|zip(env_ports_vals)) }}"
  tasks:
    - debug:
        var: env_ports

gives (abridged)

  env_ports:
    staging_core_api: 7201
    staging_import_export: 7207
    staging_stock_api: 7204
    staging_webadmin: 7209
    staging_webui: 7200

---

To simplify the code, you can create a custom filter

shell> cat filter_plugins/dict_utils.py
def prefix_key(d, prefix='prefix'):
    temp = {}
    for key in d.keys():
        temp[prefix + key] = d[key]
    return temp


class FilterModule(object):
    ''' utility filters for operating on dictionary '''
    def filters(self):
        return {
            'prefix_key': prefix_key,
        }

The playbook below gives the same result

- hosts: localhost
  vars:
    env: staging_
    ports:
      webui: 7200
      webadmin: 7209
      core_api: 7201
      stock_api: 7204
      import_export: 7207
    env_ports: "{{ ports|prefix_key(prefix=env) }}"
  tasks:
    - debug:
        var: env_ports