# Run task based on value in register **URL:** \ **Category:** Ansible Project\ **Created:** [November 12, 2020, 12:12pm UTC](https://forum.ansible.com/t/run-task-based-on-value-in-register/34184 "2020-11-12T12:12:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![dudu.c](https://avatars.discourse-cdn.com/v4/letter/d/278dde/32.png) [@dudu.c](https://forum.ansible.com/u/dudu.c)\ **Post date:** [November 12, 2020, 12:12pm UTC](https://forum.ansible.com/t/run-task-based-on-value-in-register/34184/1 "2020-11-12T12:12:31Z")
I have created a playbook that should run the following scenario – I’m having a problem with the second tasks 1. Query the source Kafka for a topic list and save the output in register 2. Run topics creation as a loop on destination kafka a. Topics list is taken from the input file b. The topic will be created only if the topic exists in the source kafka Playbook tasks explanation – It seems that task 6 is been skipped Host: source Kafka 1. Task 1 : connect to source Kafka and get a list of topic à update register 2. Task 2: print topic list – debug 3. Task 3 : Copy register output to a file Host: destination kafka 1. Task 4 : upload topic list from the file to a register 2. Task 5: print register 3. Task 6: create topic per input list, only if topic name exists in register \* If this can be done as a search in file it will be much better (will save task 4) _## Verification_ - hosts: - kafka\_source\_master\_server[0] become: true any\_errors\_fatal: true gather\_facts: False vars: zookeeper\_port: 2999 tasks: - name: list topic from source kafka command: argv: - kafka-topics - –list - –zookeeper - localhost - “{{ zookeeper\_port }}” register: kafka\_topic\_list - name: Debug - print list of Topics debug: msg: “{{kafka\_topic\_list.stdout\_lines}}” - name: write results to a file local\_action: copy content={{ kafka\_topic\_list.stdout\_lines }} dest=/tmp/topic-list.txt - hosts: - bigdata\_kafka\_master[0] become: true any\_errors\_fatal: true gather\_facts: False vars\_files: - ./environment.yml - ./kafka\_enviroment.yml vars: zookeeper\_port: 2999 srm\_bin\_path: /opt/cloudera/parcels/STREAMS\_REPLICATION\_MANAGER/bin/srm-control tasks: - name: Update register with topic list shell: cat /tmp/topic-list.txt register: topic\_list delegate\_to: localhost - name: print topics debug: msg: “{{ topic\_list.stdout\_lines }}” - name: Create duplication per topic command: argv: - “{{ srm\_bin\_path }}” - topics - –source - “{{ kafka\_source }}” - –target - “{{ kafka\_destination }}” - –add - “{{ item }}” with\_items: “{{ kafka\_topics\_to\_be\_mirrored }}” when: ‘“{{ kafka\_topics\_to\_be\_mirrored }}” in topic\_list’ ---
**Author:** ![racke](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/racke/32/4767_2.png) [@racke](https://forum.ansible.com/u/racke)\ **Post date:** [November 12, 2020, 12:33pm UTC](https://forum.ansible.com/t/run-task-based-on-value-in-register/34184/2 "2020-11-12T12:33:24Z")
> I have created a playbook that should run the following scenario – I’m having a problem with the second tasks > > 1. Query the source Kafka for a topic list and save the output in register > > 2. Run topics creation as a loop on destination kafka > > a. Topics list is taken from the input file > > b. The topic will be created only if the topic exists in the source kafka > > Playbook tasks explanation – It seems that task 6 is been skipped > > Host: source Kafka > > 1. Task 1 : connect to source Kafka and get a list of topic à update register > > 2. Task 2: print topic list – debug > > 3. Task 3 : Copy register output to a file > > Host: destination kafka > > 4. Task 4 : upload topic list from the file to a register > > 5. Task 5: print register > > 6. Task 6: create topic per input list, only if topic name exists in register \* If this can be done as a search > in file it will be much better (will save task 4) > > /## Verification > /- hosts: > - kafka\_source\_master\_server[0] > become: true > any\_errors\_fatal: true > gather\_facts: False > vars: > zookeeper\_port: 2999 > tasks: > > ``` > \- name: list topic from source kafka > command: > argv: > \- kafka\-topics > \- \-\-list > \- \-\-zookeeper > \- localhost > \- "\{\{ zookeeper\_port \}\}" > register: kafka\_topic\_list > > \- name: Debug \- print list of Topics > debug: > msg: "\{\{kafka\_topic\_list\.stdout\_lines\}\}" > > ``` > > / > > ``` > /\- name: write results to a file > local\_action: copy content=\{\{ kafka\_topic\_list\.stdout\_lines \}\} dest=/tmp/topic\-list\.txt > > ``` > > - hosts: > - bigdata\_kafka\_master[0] > become: true > any\_errors\_fatal: true > gather\_facts: False > vars\_files: > - ./environment.yml > - ./kafka\_enviroment.yml > vars: > zookeeper\_port: 2999 > srm\_bin\_path: /opt/cloudera/parcels/STREAMS\_REPLICATION\_MANAGER/bin/srm-control > tasks: > > ``` > \- name: Update register with topic list > shell: cat /tmp/topic\-list\.txt > register: topic\_list > delegate\_to: localhost > > \- name: print topics > debug: > msg: "\{\{ topic\_list\.stdout\_lines \}\}" > > \- name: Create duplication per topic > command: > argv: > \- "\{\{ srm\_bin\_path \}\}" > \- topics > \- \-\-source > \- "\{\{ kafka\_source \}\}" > \- \-\-target > \- "\{\{ kafka\_destination \}\}" > \- \-\-add > \- "\{\{ item \}\}" > with\_items: "\{\{ kafka\_topics\_to\_be\_mirrored \}\}" > when: '"\{\{ kafka\_topics\_to\_be\_mirrored \}\}" in topic\_list' > > ``` In a loop when is evaluated for \*every\* item, so I think that might solve your problem: when: item in topic\_list Regards         Racke ---
**Author:** ![dudu.c](https://avatars.discourse-cdn.com/v4/letter/d/278dde/32.png) [@dudu.c](https://forum.ansible.com/u/dudu.c)\ **Post date:** [November 12, 2020, 1:41pm UTC](https://forum.ansible.com/t/run-task-based-on-value-in-register/34184/3 "2020-11-12T13:41:27Z")
It looks that the item is not been searched in teh register - Maybe I need to implement a a regex search? if so how? ---
**Author:** ![racke](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/racke/32/4767_2.png) [@racke](https://forum.ansible.com/u/racke)\ **Post date:** [November 12, 2020, 1:54pm UTC](https://forum.ansible.com/t/run-task-based-on-value-in-register/34184/4 "2020-11-12T13:54:37Z")
> It looks that the item is not been searched in teh register - Maybe I need to implement a a regex search? if so how? Well you didn't show what is in the register and what is in kafka\_topics\_to\_be\_mirrored. Regards          Racke