Async start a process and check until its listen port condition is successful
Mohtashim S
I trigger multiple tomcat startup scripts and then need to check if all process listens on their specific port across multiple hosts in the quickest time possible.
For the test case, I m writing 3 scripts instead of tomcat scripts that runs on a single host and listen on ports 4443,4445,4447 respectively as below.
cat /tmp/startapp1.sh
while test 1 # infinite loop
sleep 10
do
nc -l localhost 4443 > /tmp/app1.log
done
cat /tmp/startapp2.sh
while test 1 # infinite loop
sleep 30
do
nc -l localhost 4445 > /tmp/app2.log
done
cat /tmp/startapp3.sh
while test 1 # infinite loop
sleep 20
do
nc -l localhost 4447 > /tmp/app3.log
done
Below is my code to trigger the script and check if the telnet is successful:
cat main.yml
- include_tasks: "internal.yml"
loop:
- /tmp/startapp1.sh 4443
- /tmp/startapp2.sh 4445
- /tmp/startapp3.sh 4447
cat internal.yml
- shell: "{{ item.split()[0] }}"
async: 600
poll: 0
- name: DEBUG CHECK TELNET
shell: "telnet {{ item.split()[1] }}"
delegate_to: localhost
register: telnetcheck
until: telnetcheck.rc == 0
async: 600
poll: 0
delay: 6
retries: 10
- name: Result of TELNET
async_status:
jid: "{{ item.ansible_job_id }}"
register: _jobs
until: _jobs.finished
delay: 6
retries: 10
with_items: "{{ telnetcheck.results }}"
Expectation: The above three scripts should start along with telnet check in about 30 seconds.
Thus, the basic check that needs to be done here is telnet until: telnetcheck.rc == 0 but due to async the telnet shell module does not have entries for rc and hence I get the below error:
"msg": "The conditional check 'telnetcheck.rc == 0' failed. The error was: error while evaluating conditional (telnetcheck.rc == 0): 'dict object' has no attribute 'rc'"
In the above code where and how can I check if telnet had succeeded i.e telnetcheck.rc == 0 and make sure the Expectation is met?
Dick Visser
such functionality?
This does what (I think!) you want:
1. run ncat (not nc) on 3 ports on the target system:
dnmvisser@villa:~$ for i in 4443 4445 4447; do ncat -l -k -p $i & done
[1] 253485
[2] 253486
[3] 253487
Consider this playbook "waitfor.yml":
---
- hosts: all
vars:
ports:
- 4443
- 4445
- 4447
tasks:
- name: Starting multiple wait_for tasks
wait_for:
port: "{{ item }}"
loop: "{{ ports }}"
register: foo
async: 600
poll: 0
changed_when: false
- name: Collecting status of wait_for tasks
async_status:
jid: "{{ item.ansible_job_id }}"
register: jobs
until: jobs.finished
delay: 1
retries: 600
loop: "{{ foo.results }}"
Run that against your target system:
ansible-playbook -i villa, waitfor.yml
The playbook should start and then get into a loop where it waits for
all 3 ports to listen.
So, while this runs, open the required sockets. I use ncat instead of nc:
dnmvisser@villa:~$ for i in 4443 4445 4447; do ncat -l -k -p $i & done
[1] 253485
[2] 253486
[3] 253487
Within 1 second the playbook will finish as all ports are now
listening on the target.
Dick
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Mohtashim S
task path: /root/newinternal.yml:17
fatal: [localhost]: FAILED! => {
"msg": "'dict object' has no attribute 'results'"
}
Dick Visser
>
> @Dick under ` - name: Starting multiple wait_for tasks` -> i do not have a loop ` loop: "{{ ports }}"` as my loop is in `main.yml` outer yml
>
> Thus, i get the following error:
>
> TASK [Collecting status of wait_for tasks] *********************************************************************************************************************************************************************
> task path: /root/newinternal.yml:17
> fatal: [localhost]: FAILED! => {
> "msg": "'dict object' has no attribute 'results'"
> }
>
> Can you please suggest?
Look at the tasks/logic of the (fully working) playbook that I
provided and adapt it to your situation.
Mohtashim S
- name: Starting services
gather_facts: false
hosts: localhost
tasks:
- include_tasks: "newinternal.yml"
loop:
- ~/startapp1.sh 4443
- ~/startapp2.sh 4445
- ~/startapp3.sh 4447
- name: Pause for 32 seconds to check telnet
pause:
seconds: 32
- include_tasks: "waitnewinternal.yml"
loop:
- ~/startapp1.sh 4443
- ~/startapp2.sh 4445
- ~/startapp3.sh 4447
async: 600
poll: 0
host: localhost
port: "{{ item.split()[1] }}"
timeout: 43
register: foo
async: 600
poll: 0
changed_when: false
async_status:
jid: "{{ foo.ansible_job_id }}"
register: jobs
until: jobs.finished
delay: 1
retries: 600