Ansible在动态清单中返回错误的主机（私有IP冲突？）

Question

I have two instances on different VPCs which have the same private address.

ci-vpc:

172.18.50.180:
    tags:
        Environment: ci
        Role: aRole

test-vpc:

172.18.50.180:
    tags:
        Environment: test
        Role: web

I am running the following playbook:

- name: "print account specific variables"
  hosts: "tag_Environment_ci:&tag_Role_web"
  tasks:
    - name: "print account specific variables for account {{ account }}"
      debug:
        msg:
          - 'ec2_tag_Name': "{{ ec2_tag_Name }}"
            'ec2_tag_Role': "{{ ec2_tag_Role }}"
            'ec2_private_ip_address': "{{ ec2_private_ip_address }}"
            'ec2_tag_Environment': "{{ ec2_tag_Environment }}"

Since I am asking for both role web and environment ci, none of these instances should be picked, but nevertheless the result that I am getting is:

ok: [172.18.50.180] => {
  "changed": false,
  "msg": [
      {
          "ec2_private_ip_address": "172.18.50.180",
          "ec2_tag_Environment": "test",
          "ec2_tag_Name": "test-web-1",
          "ec2_tag_Role": "web"
      }
  ]
}

Obviously this instance does not meet the requirements under hosts ...

It seems like ec2.py searched for the Environment tag, found ci for 172.18.50.180, then searched separately for the role tag, found another one under 172.18.50.180, and just marked that instance as ok, even though these are two different instances on different vpcs .

I've tried changing vpc_destination_variable in ec2.ini to id but then I'm getting error when Ansible is trying to connect to these instances because it cannot connect to the id...

fatal: [i-XXX]: UNREACHABLE! => {
    "changed": false, 
    "msg": "Failed to connect to the host via ssh: ssh: Could not resolve hostname i-XXX: Name or service not known\r\n", "unreachable": true
}

Is there another option that will work under vpc_destination_variable ? Any known solution for such a collision?

Answer 1

tl;dr : This is exactly what hostname_variable in ec2.ini is for, as documented:

# This allows you to override the inventory_name with an ec2 variable, instead
# of using the destination_variable above. Addressing (aka ansible_ssh_host)
# will still use destination_variable. Tags should be written as 'tag_TAGNAME'.

Unfortunetely I've missed it and found it after looking around in ec2.py

Longer answer with additional options to hostnames

After finding out about hostname_variable , I had another problem that it can receive only one variable. In my case I had some instances with the same private ip on one hand, and some with the same tags on the other (AWS autoscaling groups, same tags on all hosts), so I needed a way to differentiate between them.

I've created a gist with this option. My change is in line 848. This allows you to use multiple comma separated variables in hostname_variable , eg:

hostname_variable = tag_Name,private_ip_address