Overview
Simply enough, Ansible Tags let you run specific tasks in a play. If you have a lengthy playbook or are testing tasks within a playbook, you can assign tags to tasks that let you run a specific task vs the entire playbook.
This is simply a summary of the uses of Ansible Tags. More of a cheat sheet than trying to instruct you in how to use Ansible Tags. The Ansible Tags Documentation is fairly short and does a good job explaining how to use Ansible Tags.
Uses
Examples
$ ansible-playbook -i inventory dns-update.yaml --tags bind9 # only run tasks tagged with bind9
$ ansible-playbook -i inventory dns-update.yaml --skip-tags bind9 # run all tasks except the ones tagged with bind9
$ ansible-playbook -i inventory dns-update.yaml --tags "bind9,restart" # run tasks tagged with bind9 and restart
$ ansible-playbook -i inventory dns-update.yaml --tags untagged # only run untagged tasks
$ ansible-playbook -i inventory dns-update.yaml --tags tagged # only run tagged tasks
# ansible-playbook -i inventory dns-update.yaml --tags all # run all tasks (default)You can assign a tag to one or more tasks.
Tasks can have multiple tags.
When you create a block of tasks, you can assign a tag to that block and all tasks within the block are run when the tag is used.
An interesting idea might be to add a debug tag to all the debug statements in your playbooks and then when ready to run live, pass the –skip-tags debug flag to the playbook. Then only the tasks are executed.
Special Tags
If you assign an always tag to a task, it will always run no matter what the passed –tags value is unless you specially pass –skip-tags always.
If you assign a never tag to a task, it will not run unless you call it out specifically. Something like calling the playbook with –tags all,never.
Tag Inheritance
There are two types of statements that add tasks. A Dynamic include_role, include_tasks, and include_vars, and a Static import_role and import_tasks.
If you tag a task that contains an include_role or include_tasks function, only tasks within that included file that are similarly tagged will run when the tag is passed.
If you tag a task that contains an import_role or import_tasks function, all tasks within that imported file will be run when the tag is passed.
Listing Tags
By using the –list-tags option to ansible-playbooks, it lists all the tags and exits the playbook without running anything.
References
There are several sites that provide information on tags but the obvious one is the Ansible Documentation