# Ansible lininfile behavior **URL:** \ **Category:** Ansible Project\ **Created:** [May 4, 2020, 6:55pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845 "2020-05-04T18:55:19Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Justin\_Nelson](https://avatars.discourse-cdn.com/v4/letter/j/d6d6ee/32.png) [@Justin\_Nelson](https://forum.ansible.com/u/Justin_Nelson)\ **Post date:** [May 4, 2020, 6:55pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/1 "2020-05-04T18:55:19Z")
I have a simple playbook that I’m testing with in an attempt to update a file that has some test strings mapped to mac addresses. When I run my playbook I can only seem to get one of my two hosts to write the test string into the playbook and not both. If I run it a second time, I can get the second host in there. The plybook looks similar to the following: ` ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 8:02pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/2 "2020-05-04T20:02:49Z")
Remove "connection: local". See "local – execute on controller" [https://docs.ansible.com/ansible/latest/plugins/connection/local.html#local-execute-on-controller](https://docs.ansible.com/ansible/latest/plugins/connection/local.html#local-execute-on-controller)   "... allows ansible to execute tasks on the Ansible ‘controller’ instead of   on a remote host." HTH,   -vlado ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 8:17pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/3 "2020-05-04T20:17:38Z")
The file '/var/tmp/test.yaml' is on the remote host. Each host updates its own instance. I can only assume the file should be on the controller, e.g.      - name: Update test file        lineinfile:          path: /var/tmp/test.yaml          regexp: "^\ \ test[.-]{{ test\_string|lower }}:.\*"          line: " test-{{ test\_string|lower }}: {{ mac }}"        delegate\_to: localhost HTH,   -vlado ---
**Author:** ![Justin\_Nelson](https://avatars.discourse-cdn.com/v4/letter/j/d6d6ee/32.png) [@Justin\_Nelson](https://forum.ansible.com/u/Justin_Nelson)\ **Post date:** [May 4, 2020, 8:20pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/4 "2020-05-04T20:20:05Z")
My apologies for not being a little more clear, Vlado. I do want this to execute on the local host and not on the remote hosts. Ultimately this will be setting up a file that will be used later for building a remote host’s config file using the template module. It’s all a part of an attempt at a somewhat zero touch provisioning model for switches we deploy. Essentially the work flow would look similar to: a new device needs to be added =\> user builds initial config file specific to device location and requirements =\> user runs playbook The playbook would then locally: load the device variables from the config file take user’s config file and make a backup to the host\_vars directory for later use, if necessary take a short hostname (test\_string) and MAC address and append them to the file Later in the playbook other plays will have tasks that load the variables in these files generate a config from a template that gets copied to the remote host. This one file and its contents is, sort of, a living file that gets updated every time we add or replace a device. Hope that makes sense. ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 8:26pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/5 "2020-05-04T20:26:31Z")
If the file '/var/tmp/test.yaml' shall be created on both 'host1' and 'host2' try this     - name: Update test file       lineinfile:         path: /var/tmp/test.yaml         regexp: "^\ \ test[.-]{{ test\_string|lower }}:.\*"         line: " test-{{ test\_string|lower }}: {{ mac }}"       loop: "{{ ansible\_play\_hosts }}"       vars:         mac: "{{ hostvars[item]['mac'] }}"         test\_string: "{{ hostvars[item]['test\_string'] }}" HTH,   -vlado ---
**Author:** ![Justin\_Nelson](https://avatars.discourse-cdn.com/v4/letter/j/d6d6ee/32.png) [@Justin\_Nelson](https://forum.ansible.com/u/Justin_Nelson)\ **Post date:** [May 4, 2020, 8:26pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/6 "2020-05-04T20:26:41Z")
So I added the delegate\_to: localhost but I still only get one added on the first pass: ` PLAY [Test Playbook] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* TASK [Load device vars from config] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ok: [host1] ok: [host2] TASK [Update tmp file] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* changed: [host1 → localhost] changed: [host2 → localhost] PLAY RECAP \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* host1 : ok=2 changed=1 unreachable=0 failed=0 host2 : ok=2 changed=1 unreachable=0 failed=0 ` The file contents after that pass are: `1 macs: 2 test-host222: ab:09:87:65:43:21` And when I run it a second time: ` PLAY [Test Playbook] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* TASK [Load device vars from config] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ok: [host1] ok: [host2] TASK [Update tmp file] \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* changed: [host1 → localhost] ok: [host2 → localhost] PLAY RECAP \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* host1 : ok=2 changed=1 unreachable=0 failed=0 host2 : ok=2 changed=0 unreachable=0 failed=0 ` With the file contents now the following: `1 macs: 2 test-host222: ab:09:87:65:43:21 3 test-host111: 12:34:56:78:90:ab` ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 4, 2020, 8:31pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/7 "2020-05-04T20:31:49Z")
Since you have two host you will have two tasks that tries to write to the same file at the same time, and only one of them will win. Add "throttle: 1" to you lineinfile task and it will work. ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 8:49pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/8 "2020-05-04T20:49:38Z")
> \> [test\_group] > \> host1 > \> host2 > > Since you have two host you will have two tasks that tries to write to the same > file at the same time, and only one of them will win. > > Add "throttle: 1" to you lineinfile task and it will work. I don't need "throttle" with 2.9.6. The playbook > cat pb.yml - hosts:     - test\_01     - test\_02   gather\_facts: false   tasks:     - lineinfile:         path: test-file         line: "{{ inventory\_hostname }}"       delegate\_to: localhost gives > cat test-file > ansible-playbook pb.yml PLAY [test\_01,test\_02] ---
**Author:** ![Justin\_Nelson](https://avatars.discourse-cdn.com/v4/letter/j/d6d6ee/32.png) [@Justin\_Nelson](https://forum.ansible.com/u/Justin_Nelson)\ **Post date:** [May 4, 2020, 9:02pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/9 "2020-05-04T21:02:13Z")
The two hosts I have to test with are running 2.7.4 and 2.8.2. I don’t have a 2.9.x host available to test the throttle command but it makes sense. However, when I updated the playbook to the following: ` ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 9:04pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/10 "2020-05-04T21:04:30Z")
> The file contents after that pass are: > >   1 macs: >   2 test-host222: ab:09:87:65:43:21 > > And when I run it a second time: > >   1 macs: >   2 test-host222: ab:09:87:65:43:21 >   3 test-host111: 12:34:56:78:90:ab It's working for me as expected > cat test\_01.conf test\_string: abc mac: 01:23:45:67:89:ab > cat test\_02.conf test\_string: xyz mac: ab:09:87:65:43:21 > cat pb.yml - hosts:     - test\_01     - test\_02   tasks:     - include\_vars: "{{ inventory\_hostname }}.conf"     - name: Update test file       lineinfile:         path: test-file         regexp: "^\ \ test[.-]{{ test\_string|lower }}:.\*"         line: " test-{{ test\_string|lower }}: {{ mac }}"       delegate\_to: localhost > cat test-file > ansible-playbook pb.yml PLAY [test\_01,test\_02] ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 4, 2020, 9:06pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/11 "2020-05-04T21:06:50Z")
That is just pure luck, try running it 100 times and count how many times it fails. ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 4, 2020, 9:18pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/12 "2020-05-04T21:18:03Z")
Here also you have two task writing to the same file at the same time. So here you need to add "run\_once: yes" to the lineinfile task. ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 9:19pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/13 "2020-05-04T21:19:53Z")
> The file contents after that pass are: > >   1 macs: >   2 test-host222: ab:09:87:65:43:21 > > With the file contents now the following: > >   1 macs: >   2 test-host222: ab:09:87:65:43:21 >   3 test-host111: 12:34:56:78:90:ab Bingo! I'm able to reproduce the problem with Ansible running on controller with Python 2.7 > ansible --version ansible 2.9.6   config file = /export/scratch/tmp/ansible.cfg   configured module search path = [u'/home/vlado/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules'] ansible python module location = /usr/lib/python2.7/dist-packages/ansible executable location = /usr/bin/ansible python version = 2.7.17 (default, Nov 7 2019, 10:07:09) [GCC 7.4.0] There is no such problem with Ansible running on controller with Python 3 > ansible --version ansible 2.9.6   config file = /home/vlado/.ansible.cfg   configured module search path = ['/home/vlado/.ansible/my\_modules']   ansible python module location = /usr/lib/python3/dist-packages/ansible   executable location = /usr/bin/ansible   python version = 3.8.2 (default, Apr 27 2020, 15:53:34) [GCC 9.3.0] HTH,   -vlado ---
**Author:** ![Justin\_Nelson](https://avatars.discourse-cdn.com/v4/letter/j/d6d6ee/32.png) [@Justin\_Nelson](https://forum.ansible.com/u/Justin_Nelson)\ **Post date:** [May 4, 2020, 9:46pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/14 "2020-05-04T21:46:07Z")
The main one I’m testing with is running python 3.6 > $ ansible --version > ansible 2.7.4 > config file = /etc/ansible/ansible.cfg > configured module search path = [‘/home/ofoo/.ansible/plugins/modules’, ‘/usr/share/ansible/plugins/modules’] > ansible python module location = /usr/local/lib/python3.6/dist-packages/ansible > executable location = /usr/local/bin/ansible > python version = 3.6.9 (default, Apr 18 2020, 01:56:04) [GCC 8.4.0] ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 9:55pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/15 "2020-05-04T21:55:14Z")
Well, I tried and it's working properly with Python3. There is no problem with Ansible 2.9.6 and Python 3.8 on the controller ( the redirection in the script '2\>/dev/null' is there because of annoying 3.8 RuntimeWarning).   #!/bin/bash   export ANSIBLE\_STDOUT\_CALLBACK=null   for i in {1..99}; do       ansible-playbook pb.yml 2\>/dev/null       no\_lines=`cat test-file | wc -l`       [$no\_lines -ne 2] && echo "ERROR File 2 lines missing"       cat /dev/null \> test-file       no\_lines=`cat test-file | wc -l`       [$no\_lines -ne 0] && echo "ERROR File not empty"   done But, you were right with "throttle". With Ansible 2.9.6 and Python 2.7 on the controller "throttle: 1" fixed the problem     - name: Update test file       lineinfile:         path: test-file         regexp: "^\ \ test[.-]{{ test\_string|lower }}:.\*"         line: " test-{{ test\_string|lower }}: {{ mac }}"       delegate\_to: localhost       throttle: 1 Thank you,   -vlado ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 4, 2020, 10:02pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/16 "2020-05-04T22:02:40Z")
> \> The file contents after that pass are: > \> > \> 1 macs: > \> 2 test-host222: ab:09:87:65:43:21 > \> > \> With the file contents now the following: > \> > \> 1 macs: > \> 2 test-host222: ab:09:87:65:43:21 > \> 3 test-host111: 12:34:56:78:90:ab > > Bingo! I'm able to reproduce the problem with Ansible running on controller > with Python 2.7 \ > There is no such problem with Ansible running on controller with Python 3 That's just not true, your test method is flawed, you need to test it more than one time. $ ansible-playbook --version | awk 'NR==1; END{print}' ansible-playbook 2.9.7   python version = 3.7.5 (default, Apr 19 2020, 20:18:17) [GCC 9.2.1 20191008] $ cat test.yml - hosts: a1,a2   tasks:     - lineinfile:         path: /tmp/txt         line: "{{ inventory\_hostname }}"       delegate\_to: localhost $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; md5sum /tmp/txt; done | sort | uniq -c | sort -n       4 763950971c8c6d8df8a87a1e752799a9 /tmp/txt      11 1597a5a9948014489de663c8fb4438db /tmp/txt      36 ac34af7b876f793d09a2225e23f43088 /tmp/txt      49 317f53fd9236220d0ab65e4aac4b3c5a /tmp/txt So as you can see I get 4 different result as expected. $ cat a1; md5sum a1 a1 763950971c8c6d8df8a87a1e752799a9 a1 $ cat a2; md5sum a2 a2 1597a5a9948014489de663c8fb4438db a2 $ cat a1a2; md5sum a1a2 a1 a2 317f53fd9236220d0ab65e4aac4b3c5a a1a2 $ cat a2a1; md5sum a2a1 a2 a1 ac34af7b876f793d09a2225e23f43088 a2a1 ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 4, 2020, 10:47pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/17 "2020-05-04T22:47:10Z")
> \> There is no such problem with Ansible running on controller with Python 3 > > That's just not true, your test method is flawed, you need to test it more than one time. > > $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; md5sum /tmp/txt; done | sort | uniq -c | sort -n >       4 763950971c8c6d8df8a87a1e752799a9 /tmp/txt >      11 1597a5a9948014489de663c8fb4438db /tmp/txt >      36 ac34af7b876f793d09a2225e23f43088 /tmp/txt >      49 317f53fd9236220d0ab65e4aac4b3c5a /tmp/txt > > So as you can see I get 4 different result as expected. > $ cat a1; md5sum a1 > a1 > 763950971c8c6d8df8a87a1e752799a9 a1 > $ cat a2; md5sum a2 > a2 > 1597a5a9948014489de663c8fb4438db a2 > $ cat a1a2; md5sum a1a2 > a1 > a2 > 317f53fd9236220d0ab65e4aac4b3c5a a1a2 > $ cat a2a1; md5sum a2a1 > a2 > a1 > ac34af7b876f793d09a2225e23f43088 a2a1 Well, it is true. There are no problems reported with your method either. I get correct results only. > for i in {1..100}; do \>test-file; ansible-playbook pb.yml 2\>/dev/null; md5sum test-file; done | sort | uniq -c | sort -n      18 82de37d1deac8c90573c35e5637839d7 test-file      82 6f4e9c06436257db5ba34d527bd3b211 test-file > cat test\_01test\_02; md5sum test\_01test\_02 test\_01 test\_02 6f4e9c06436257db5ba34d527bd3b211 test\_01test\_02 > cat test\_02test\_01; md5sum test\_02test\_01 test\_02 test\_01 82de37d1deac8c90573c35e5637839d7 test\_02test\_01 > ansible --version ansible 2.9.6   config file = /home/vlado/.ansible.cfg   configured module search path = ['/home/vlado/.ansible/my\_modules']   ansible python module location = /usr/lib/python3/dist-packages/ansible   executable location = /usr/bin/ansible   python version = 3.8.2 (default, Apr 27 2020, 15:53:34) [GCC 9.3.0] ---
**Author:** ![vbotka](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/vbotka/32/359_2.png) [@vbotka](https://forum.ansible.com/u/vbotka)\ **Post date:** [May 5, 2020, 7:19am UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/18 "2020-05-05T07:19:50Z")
> \> \> There is no such problem with Ansible running on controller with Python 3 > \> > \> That's just not true, your test method is flawed, you need to test it more than one time. > \> > \> $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; md5sum /tmp/txt; done | sort | uniq -c | sort -n > \> 4 763950971c8c6d8df8a87a1e752799a9 /tmp/txt > \> 11 1597a5a9948014489de663c8fb4438db /tmp/txt > \> 36 ac34af7b876f793d09a2225e23f43088 /tmp/txt > \> 49 317f53fd9236220d0ab65e4aac4b3c5a /tmp/txt > > Well, it is true. There are no problems reported with your method either. I > get correct results only. > > \> for i in {1..100}; do \>test-file; ansible-playbook pb.yml 2\>/dev/null; md5sum test-file; done | sort | uniq -c | sort -n >      18 82de37d1deac8c90573c35e5637839d7 test-file >      82 6f4e9c06436257db5ba34d527bd3b211 test-file To be sure, I let it run overnight > for i in {1..10000}; do \>test-file; ansible-playbook -i hosts77 test77.yml 2\>/dev/null; md5sum test-file; done | sort | uniq -c | sort -n    2689 82de37d1deac8c90573c35e5637839d7 test-file    7311 6f4e9c06436257db5ba34d527bd3b211 test-file ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 5, 2020, 8:06pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/19 "2020-05-05T20:06:04Z")
That is not true and has nothing to do with Python version, and everything with a little luck and a fast computer. The test case is flawed for your Ansible controller, if it had more load and/or more hosts you would get a completely different result. The reason why this i not reliable is that Ansible is default running forks of 5, that mean that if you had 5 or more hosts it will run/fork out 5 commands. This 5 commands will try to edit the same file at the same time. Reason it works for you is that the first fork is finished before the second has time to start. This is how Ansible work, and now Python version is going to alter that. And I'm going to prove it. Since my machine doesn't have Python 3.8 I created a VM, with 2 cores. $ ansible-playbook --version | awk 'NR==1; END{print}' ansible-playbook 2.9.7   python version = 3.8.2 (default, Mar 24 2020, 03:08:36) [GCC 9.3.0] So when I run my playbook with two host I get this $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; md5sum /tmp/txt; done | sort | uniq -c | sort -n       1 1597a5a9948014489de663c8fb4438db /tmp/txt      39 317f53fd9236220d0ab65e4aac4b3c5a /tmp/txt      60 ac34af7b876f793d09a2225e23f43088 /tmp/txt and the next time $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; md5sum /tmp/txt; done | sort | uniq -c | sort -n       1 1597a5a9948014489de663c8fb4438db /tmp/txt      43 317f53fd9236220d0ab65e4aac4b3c5a /tmp/txt      56 ac34af7b876f793d09a2225e23f43088 /tmp/txt As you can see it fails i 1 % of the cases. Lets up the stake and go for 6 hosts, the playbook is the same, but since 6 hosts make potensial a lot of combination, I sort the file before I run md5sum. So if everything is working OK I should only get one line with one hash like this    100 aae4eb078da77ff549495a60be1a52c2 $ for i in {1..100}; do \>/tmp/txt; ansible-playbook test.yml &\>/dev/null; sort /tmp/txt | md5sum; done | sort | uniq -c | sort -n       1 2465fc0f03254f2bf915a04c762c9d49 -       2 254316531e34aa3ce563c22cf636ea01 -       2 31f07322fb0283ee5475e5acc74de059 -       2 ab8ecb5209d15e9852be208b79f309eb -       3 7abbd5c371c5e4ccb8bc965105148605 -      90 aae4eb078da77ff549495a60be1a52c2 - Not even close, it fails in 10% of the runs. So lets make the machine even more busy. To do that I shutdown the VM and reduced the cores count from 2 to 1. Now we have 5 forks at the same time "fighting" for this 1 core and trying to write to the same file at the same time. This is the result.       1 254316531e34aa3ce563c22cf636ea01 -       1 6c5ffba74557139441576f9f6536c536 -       1 8da4fee8643e840ae60169eac2d60afd -       1 9a7861beaa38064dd7179cf66b90173f -       1 aae4eb078da77ff549495a60be1a52c2 -       1 d5fad8b2b8f31c4d201309e2261ee362 -       2 2465fc0f03254f2bf915a04c762c9d49 -       2 2ea77912754b2a786046ece007bfd0a7 -       2 6503321b7879267a6a5eb06411e09b5e -       2 9ce72c8f1a3f059db908868df22c2618 -       2 ab8ecb5209d15e9852be208b79f309eb -       2 adc72709b7b7cdc8aaad85c01b66e38d -       2 c4b05365f19a397fc9b2dda817219d49 -       2 cf2b918385c6d1f75d7a0630d8881422 -       2 d678deb816d9433ff1c61d60ec1073f1 -       3 83758fc71d9927b3141c325692534add -       3 989fe3db59b18149e58657daab4721dc -       3 a421781f0d1512c9c66e9f7714bed570 -       4 7bc2be35864ae017608466e62dd680aa -       5 83ba567764a618ec0a0b405d49de8fa9 -       5 c98ae97d4888d870d9a05fe7f9b339a3 -       5 d336136909e4067c35858990dd4f9211 -       6 31f07322fb0283ee5475e5acc74de059 -       6 76aabdf63a1f041f6572fb51fb496283 -       6 cce45b22f8bc7806e3dc1128980f33f6 -       6 cce83e09262e3efced931d81c85ac809 -       6 decd8e81f11339ba387cb7cf61a28f34 -       7 aed3d7850c9c5478d84bf78fdc922328 -      11 d8ee7367ba9763647a58ab23a6f01c5f - Yeah, it fails miserably, in 99% of the cases. The correct md5sum is this one $ cat sorted.txt a1 a2 a3 a4 a5 a6 $ md5sum sorted.txt aae4eb078da77ff549495a60be1a52c2 sorted.txt So no combination of Ptyhon and Ansible released will alter this, it's just how it work. That is why we have serial, fork and throttle to tune the behavior to avoid race conditions. ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [May 5, 2020, 8:10pm UTC](https://forum.ansible.com/t/ansible-lininfile-behavior/32845/20 "2020-05-05T20:10:01Z")
I have explained in my previous mail why this is by change/luck, and it will fail if you controller had some more load that just 2 hosts. [Next page](https://forum.ansible.com/t/ansible-lininfile-behavior/32845.md?page=2)