4.5 Task control
In this lab we learn about task control.
Task 1
- Write an ad-hoc command that sleeps for 1000 seconds and runs on
node1 - Ensure that the command times out after 10 seconds if not completed by then. Run the task.
- Use the
time command to see how long your ad-hoc command had to run. Use man time to see how time works. - Now add a polling interval of 30 seconds. Run the task, and ensure with the
time command, that it had a longer runtime. - See what happens if you only specify the polling interval but no async timeout. Tip: set a sleep duration of only 10 seconds.
Solution Task 1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
| $ ansible node1 -B 10 -a "/usr/bin/sleep 1000"
node1 | FAILED | rc=-1 >>
Timeout exceeded
$ time ansible node1 -B 10 -a "/usr/bin/sleep 1000"
node1 | FAILED | rc=-1 >>
Timeout exceeded
real 0m17.461s
user 0m1.564s
sys 0m0.253s
$ time ansible node1 -B 10 -P 30 -a "/usr/bin/sleep 1000"
node1 | FAILED | rc=-1 >>
Timeout exceeded
real 0m32.625s #<- more than the polling interval
user 0m5.541s
sys 0m0.684s
|
Setting the poll parameter without the async parameter results in the job not beeing put in background.
1
2
3
| $ ansible node1 -P 30 -a "/usr/bin/sleep 10"
node1 | CHANGED | rc=0 >>
$
|
Task 2
- Write a playbook
async.yml that does the same as in the task above: - Run a command that sleeps for 1000 second and runs on
node1. - Let the task wait at most for 10 seconds before timing out.
- Run the task.
Solution Task 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
| $ cat async.yml
---
- hosts: node1
tasks:
- name: sleeping beauty
command: "/usr/bin/sleep 1000"
async: 10
$ ansible-playbook async.yml
PLAY [node1] **************************************************************************************************************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************************************************************************************************
ok: [node1]
TASK [sleeping beauty] ****************************************************************************************************************************************************************************************
fatal: [node1]: FAILED! => {"changed": false, "msg": "async task did not complete within the requested time - 10s"}
PLAY RECAP ****************************************************************************************************************************************************************************************************
node1 : ok=1 changed=0 unreachable=0 failed=1 skipped=0 rescued=0 ignored=0
$
|
Task 3 (Advanced)
In the playbook async.yml do the following:
- Put the task above in the background and change the values of the sleepduration, polling interval and async time to reasonable values.
- Check back with an
async_status task if the sleep-task has finished. - Run the playbook.
Tip
If unsure, check the documentation about
async_status for an example.
Solution Task 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
| $ cat async.yml
---
- hosts: node1
tasks:
- name: sleeping beauty
command: "/usr/bin/sleep 30"
async: 60
poll: 0
register: sleepingbeauty
- name: check back if task in background has finished
async_status:
jid: '{{ sleepingbeauty.ansible_job_id }}'
register: beauty_status
until: beauty_status.finished
retries: 50
$ ansible-playbook async.yml
PLAY [node1] **************************************************************************************************************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************************************************************************************************
ok: [node1]
TASK [sleeping beauty] ****************************************************************************************************************************************************************************************
changed: [node1]
TASK [check back if task in background has finished] **********************************************************************************************************************************************************
FAILED - RETRYING: check back if task in background has finished (50 retries left).
FAILED - RETRYING: check back if task in background has finished (49 retries left).
FAILED - RETRYING: check back if task in background has finished (48 retries left).
FAILED - RETRYING: check back if task in background has finished (47 retries left).
FAILED - RETRYING: check back if task in background has finished (46 retries left).
FAILED - RETRYING: check back if task in background has finished (45 retries left).
changed: [node1]
PLAY RECAP ****************************************************************************************************************************************************************************************************
node1 : ok=3 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
$
|
All done?