How to run only one task in an unoccupied play?

Question

Is there a way to run only one task in a playbook inaccessible to view?

For example, in roles/hadoop_primary/tasks/hadoop_master.yml . I have a task "start hadoop job tracker services" . Is it possible to run only one task?

Hadoop_master.yml file:

 --- # Playbook for Hadoop master servers - name: Install the namenode and jobtracker packages apt: name={{item}} force=yes state=latest with_items: - hadoop-0.20-mapreduce-jobtracker - hadoop-hdfs-namenode - hadoop-doc - hue-plugins - name: start hadoop jobtracker services service: name=hadoop-0.20-mapreduce-jobtracker state=started tags: debug 

Answer 1

You should use tags: as described in http://docs.ansible.com/playbooks_tags.html

---

If you have a large playbook, it may be useful to run a specific part of the configuration without starting the entire tutorial.

Both games and tasks support the "tags:" attribute for this reason.

Example:

 tasks: - yum: name={{ item }} state=installed with_items: - httpd - memcached tags: - packages - template: src=templates/src.j2 dest=/etc/foo.conf tags: - configuration 

If you want to just run part of the “configuration” and “packages” from a very long piece, you can do this:

 ansible-playbook example.yml --tags "configuration,packages" 

On the other hand, if you want to run a playbook without specific tasks, you can do this:

 ansible-playbook example.yml --skip-tags "notification" 

You can also apply tags to roles:

 roles: - { role: webserver, port: 5000, tags: [ 'web', 'foo' ] } 

And you can also flag basic include statements:

 - include: foo.yml tags=web,foo 

Both of them have the function of marking each individual task inside the include statement.

Answer 2

There is a way, though not very elegant:

• ansible-playbook roles/hadoop_primary/tasks/hadoop_master.yml --step --start-at-task='start hadoop jobtracker services'
• You will receive an invitation: Perform task: start hadoop jobtracker services (y/n/c)
• Answer y
• The following prompt appears, press Ctrl-C

Answer 3

I would love the opportunity to use the role as a set of tasks, so in my book I can choose which subset of the tasks to run. Unfortunately, a playbook can only load them all, and then you have to use the --tags option in cmdline to select the tasks to run. The problem is that all tasks will be performed if you do not remember the installation of --tags or --skip-tags .

I installed some tasks, however, with the when: clause, which will only work when var is installed.

eg.

 # role/stuff/tasks/main.yml - name: do stuff when: stuff|default(false) 

Now this task will not work by default, but only if I set stuff=true

 $ ansible-playbook -e '{"stuff":true}' 

or in the textbook:

 roles: - {"role":"stuff", "stuff":true} 

Answer 4

FWIW with Ansible 2.2 can use include_role :

playbook test.yml :

 - name: test hosts: - 127.0.0.1 connection: local tasks: - include_role: name: test tasks_from: other 

then in roles/test/tasks/other.yml :

 - name: say something else shell: echo "I'm the other guy" 

And call the playbook with: ansible-playbook test.yml to get:

 TASK [test : say something else] ************* changed: [127.0.0.1] 

Answer 5

Do you know handlers ? I think this is what you are looking for. Move the restart from hadoop_master.yml to roles/hadoop_primary/handlers/main.yml :

 - name: start hadoop jobtracker services service: name=hadoop-0.20-mapreduce-jobtracker state=started 

and now use notify in hadoop_master.yml :

 - name: Install the namenode and jobtracker packages apt: name={{item}} force=yes state=latest with_items: - hadoop-0.20-mapreduce-jobtracker - hadoop-hdfs-namenode - hadoop-doc - hue-plugins notify: start hadoop jobtracker services 

Answer 6

This can be easily done using tags.

An example tag is defined below:

 --- hosts: localhost tasks: - name: Creating s3Bucket s3_bucket: name: ansiblebucket1234567890 tags: - createbucket - name: Simple PUT operation aws_s3: bucket: ansiblebucket1234567890 object: /my/desired/key.txt src: /etc/ansible/myfile.txt mode: put tags: - putfile - name: Create an empty bucket aws_s3: bucket: ansiblebucket12345678901234 mode: create permission: private tags: - emptybucket 

to execute tags we use the command

 ansible-playbook creates3bucket.yml --tags "createbucket,putfile"