Ansible module lineinfile doesn't properly write all the output - ansible

Question

I've written a small playbook to run the sudo /usr/sbin/dmidecode -t1 | grep -i vmware | grep -i product command and write the output in a result file by usign the following code as a .yml:
# Check if server is vmware
---
- name: Check if server is vmware
hosts: all
become: yes
#ignore_errors: yes
gather_facts: False
serial: 50
#become_flags: -i
tasks:
- name: Run uptime command
#become: yes
shell: "sudo /usr/sbin/dmidecode -t1 | grep -i vmware | grep -i product"
register: upcmd
- debug:
msg: "{{ upcmd.stdout }}"
- name: write to file
lineinfile:
path: /home/myuser/ansible/mine/vmware.out
create: yes
line: "{{ inventory_hostname }};{{ upcmd.stdout }}"
delegate_to: localhost
#when: upcmd.stdout != ""
When running the playbook against a list of hosts I get different weird results so even if the debug shows the correct output, when I check the /home/myuser/ansible/mine/vmware.out file I see only part of them being present. Even weirder is that if I run the playbook again, I will correctly populate the whole list but only if I run this twice. I have repeated this several times with some minor tweaks but not getting the expected result. Doing -v or -vv shows nothing unusual.

Answer 1

You are writing to the same file in parallel on localhost. I suspect you're hitting a write concurrency issue. Try the following and see if it fixes your problem:
- name: write to file
lineinfile:
path: /home/myuser/ansible/mine/vmware.out
create: yes
line: "{{ host }};{{ hostvars[host].upcmd.stdout }}"
delegate_to: localhost
run_once: true
loop: "{{ ansible_play_hosts }}"
loop_control:
loop_var: host

Answer 2

From your described case I understand that you like to find out "How to check if a server is virtual?"
The information will already be collected by the setup module.
---
- hosts: linux_host
become: false
gather_facts: true
tasks:
- name: Show Gathered Facts
debug:
msg: "{{ ansible_facts }}"
For an under MS Hyper-V virtualized Linux system, the output could contain
...
bios_version: Hyper-V UEFI Release v1.0
...
system_vendor: Microsoft Corporation
uptime_seconds: 2908494
...
userspace_architecture: x86_64
userspace_bits: '64'
virtualization_role: guest
virtualization_type: VirtualPC
and having already the uptime in seconds included
uptime
... up 33 days ...
For just only a virtual check one could gather_subset resulting into a full output of
gather_subset:
- '!all'
- '!min'
- virtual
module_setup: true
virtualization_role: guest
virtualization_type: VirtualPC
By Caching facts
... you have access to variables and information about all hosts even when you are only managing a small number of servers
on your Ansible Control Node. In ansible.cfg you can configure where and how they are stored and for how long.
fact_caching = yaml
fact_caching_connection = /tmp/ansible/facts_cache
fact_caching_timeout = 86400 # seconds
This would be a minimal and simple solution without re-implementing functionality which is already there.
Further Documentation and Q&A
Ansible facts
What is the exact list of Ansible setup min?