Ansible issuing warning about localhost

Question

I am running the following ansible playbook

- hosts: localhost
  connection: local
  vars_files:
    - vars/config_values.yaml

  gather_facts: no

  tasks:
    - name: Set correct project in gcloud config
      shell: "gcloud config set project {{ google_project_name }}"

Which yields the following warning:

[WARNING]: No inventory was parsed, only implicit localhost is available

[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

Given that I am explicitly stating that it will be run against host: localhost, why is it complaining about no inventory being parsed and that the "provided host list is empty"?

How to remove these warnings? (without just suppressing them if possible)

Answer 1

This is just a warning telling you that you did not provide any inventory file (with -i), that the default one (usually /etc/ansible/hosts) could not be found and therefore your inventory is empty, only containing the implicit localhost.

hosts: localhost is the target for your play. It can be a host or a group (or a more complicated pattern). The targeted hosts must exist in the inventory to be managed. localhost always exists as the implicit local machine.

See https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html

If your default inventory will stay empty and you basically only run playbooks targeted to localhost, you can suppress this warning by setting a config option in your environment or in ansible cfg (Thanks @larsk for the pull request adding this feature).

Answer 2

As a non-expert. in Ansible, I suppressed these messages by adding localhost on the /etc/ansible/hosts. Then set hosts: localhost on the playbook file. You should be good and won't be seeing those warning messages.

Hosts file

[ec2-user@ip-192-168-1-38 ~]$ sudo head -20 /etc/ansible/hosts
# This is the default ansible 'hosts' file.
#
# It should live in /etc/ansible/hosts
#
#   - Comments begin with the '#' character
#   - Blank lines are ignored
#   - Groups of hosts are delimited by [header] elements
#   - You can enter hostnames or ip addresses

#   - A hostname/ip can be a member of multiple groups

# Ex 1: Ungrouped hosts, specify before any group headers.
localhost
## green.example.com
## blue.example.com
## 192.168.100.1
## 192.168.100.10

# Ex 2: A collection of hosts belonging to the 'webservers' group

## [webservers]

Playbook file

[ec2-user@ip-192-168-1-38  ~]$ cat msteams.yml
  - name: MSTeams    
    hosts: localhost
    connection: local
    gather_facts: false
    tasks:
    - name: MSTeams Sending
      uri:
        url: https://outlook.office.com/webhook/asdasda-asdasd-40sdfd-btryrty2-posadjfm,sdnfoersmdnrfoasf,mvmnmtrny40956839523842/IncomingWebhook/102938091283kdjoasdyo214/vnmlasdhfaosldnaehywe
        method: POST
        body: "{\"text\": \"**Header:** {{Header}}\n\n **Next Line Message1:** {{MESSAGE1}}\n\n **Next Line Message2:** '{{ MESSAGE2 }}'\", \"themeColor\": \"{{COLOR}}\"}"
        body_format: json
        headers:
          Content-Type: "application/json"

Command Result

[ec2-user@ip-192-168-1-38 ~]$ ansible-playbook msteams.yml -e "Header=TEST" -e "MESSAGE1=Message_without_space" -e ' MESSAGE2="Message with space" ' -e "COLOR=##FF0000"

PLAY [MSTeams] ***********************************************************************************************************************************************************************************************

TASK [MSTeams Sending] ************************************************************************************************************************************************************************************
ok: [localhost]


PLAY RECAP ****************************************************************************************************************************************************************************************************************
localhost                 : ok=1    changed=0    unreachable=0    failed=0

Answer 3

As of ansible 2.6 you can also run ANSIBLE_LOCALHOST_WARNING=false ansible-playbook /path/to/your/playbook.yaml or set "localhost_warning=false" in your ansible.cfg file

https://docs.ansible.com/ansible/latest/reference_appendices/config.html#localhost-warning