How to use Ansible module 'wait_for' together with 'loop'?

Question

In Ansible 2.7.11 and wanted to use the module waif_for together with loops for connection test to my System Center Operations Manager (SCOM) servers.

Currently I’m using a task

- name: "Test connection to SCOM_MGMT_SRV_PROD: {{ SCOM_MGMT_SRV_PROD }}"
  wait_for:
    host: "{{ item }}"
    port: "{{ SCOM_PORT }}"
    state: drained         # Port should be open
    delay: 0               # No wait before first check (sec)
    timeout: 3             # Stop checking after timeout (sec)
    active_connection_states: SYN_RECV
  with_items:
    - server1
    - server2
    - server3
    - server4
  ignore_errors: yes
  tags: connectionTest,testSCOM

where the variable SCOM_PORT is set to 1270 and SCOM_MGMT_SRV_PROD to a list of servers "server1,server2,server3,server4".

This approach is working but I wanted to have a variable list of servers maintained at a central place, like a global variable SCOM_MGMT_SRV_PROD in inventory file.

It is possible to iterate over such a list via

- debug:
    msg="{{ item }}"
  loop: "{{ [SCOM_MGMT_SRV_PROD] }}"

but when using this approach in the task

- name: "Test connection to SCOM_MGMT_SRV_PROD: {{ SCOM_MGMT_SRV_PROD }}"
  wait_for:
    host: "{{ item }}"
    port: "{{ SCOM_PORT }}"
    state: drained         # Port should be open
    delay: 0               # No wait before first check (sec)
    timeout: 3             # Stop checking after timeout (sec)
    active_connection_states: SYN_RECV
  loop: "{{ [SCOM_MGMT_SRV_PROD] }}"
  ignore_errors: yes
  tags: connectionTest,testSCOM

I’m getting an error

failed: [host] (item=server1,server2,server3,server4) => ... /tmp/ansible_wait_for_payload_zNj2ac/__main__.py", line 380, in _convert_host_to_hexrn  File "/tmp/ansible_wait_for_payload_zNj2ac/__main__.py", line 354, in _convert_host_to_iprnsocket.gaierror: [Errno -2] Name or service not knownrn", "msg": "MODULE FAILUREnSee stdout/stderr for the exact error", "rc": 1}

which for me indicates that the module wait_for got the full list as item instead of one server from the list. The reason for the described behavior seems to be answered @https://stackoverflow.com/questions/48351187/.

Any idea how to get the module wait_for working with a variable list of servers?

Other Components

RHEL 7.6
python version = 2.7.5 (default, Jun 11 2019, 12:19:05) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
Module dig is installed, but not used since it doesn’t change the behavior together with lookup

Asked By: U880D

||

Source

Answer 1

After consulting with colleagues it turned out that the list (of servers) wasn’t defined correctly in inventory, just a classical syntax error. Please see Ansible, how to define a list in host inventory?.

To get it working it is necessary to define in inventory file the variable as

SCOM_MGMT_SRV_PROD="['server1','server2','server3','server4']"

instead of an just comma separated list of strings and use for loop

loop: "{{ SCOM_MGMT_SRV_PROD }}"

By doing this I’ve realized that actually the debug message wasn’t iterating over the list either. Now it is working properly

TASK [debug] ************************************************************************************************************************
ok: [host] => (item=server1) => {
    "msg": "server1"
}
ok: [host] => (item=server2) => {
    "msg": "server2"
}
ok: [host] => (item=server3) => {
    "msg": "server3"
}
ok: [host] => (item=server4) => {
    "msg": "server4"
}

TASK [Test connection to SCOM_MGMT_SRV_PROD: ['server1','server2','server3','server4']] ***
ok: [host] => (item=server1)
ok: [host] => (item=server2)
ok: [host] => (item=server3)
ok: [host] => (item=server4)

Meanwhile I’ve found out also that it is possible to Looping over inventory and if I use

with_items: "{{ groups['SCOM_MGMT_SRV_PROD'] }}"

together with a group in inventory file

[SCOM_MGMT_SRV_PROD]
server1
server2
server3
server4

Since the monitoring servers are not part of infrastructure which is maintained by Ansible, Linux admins, etc., I do not like to include them in the inventory other than in a variable.

Are there any other options to loop over a variable list of servers? … if not, it might be necessary to go with this as solution.

Answered By: U880D

How to use Ansible module 'wait_for' together with 'loop'?

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