How to continue execution on failed task after fixing error in playbook?

Question

When writing and debugging Ansible playbooks, typical workflow is as follows:

1. ansible-playbook ./main.yaml
2. Playbook fails on some task
3. Fix this task and repeat line 1, waiting for all previous tasks to execute again. Which takes a lot of time

Ideally, i'd like to resume execution on failed task, having inventory and all facts collected by previous tasks. Is it even possible? How to make playbook writing/debugging faster?

Answer 1

Take a look at Executing playbooks for troubleshooting. If you want to start executing your playbook at a particular task, you can do so with the --start-at-task option:

ansible-playbook playbook.yml --start-at-task="install packages" 

The above will start executing your playbook at a task named “install packages”.

Alternatively, take a look at this previous answer How to run only one task in ansible playbook?

Finally, when a play fails, it usually gives you something along the lines of:

PLAY RECAP ********************************************************************             to retry, use: --limit @/home/user/site.retry 

Use that --limit command and it should retry from the failed task.

Answer 2

Future readers:

The --limit @/home/user/site.retry would not help in such a scenario, the .retry only stores the failed host and nothing more, so will just execute all tasks against failed hosts.

If you are using the latest version (Ansible 2.x) the --start-at-task does not work for tasks defined inside roles.

You can achieve similar effect by just using the --step flag e.g: ansible-playbook playbook.yml --step. The step asks you on before executing each task and you could choose (N)o/(y)es/(c)ontinue.

With this approach you selectively execute tasks when needed and also continue from point where it failed, after fixes.