play_hosts with serial includes only the hosts of the current batch

[Ivaylo Bratoev]

When running a playbook with *serial* the *play_hosts* variable includes the hosts just of the current batch. I think this is unexpected and can lead to various issues, especially with the cases where *play_hosts* is generally used (from docs: "This may be useful for filling out templates with multiple hostnames or for injecting the list into the rules for a load balancer"). Is this classified as a bug or known feature?

It seems this is related to the fact that *run_once* tasks in a *serial* play are run once per host batch.

[Hagai Kariti]

I had situations when this proved useful and situations when this proved annoying :) i'd love a finer control on this.

On Mon, Aug 17, 2015, 18:54 Ivaylo Bratoev <ivaylo....@gmail.com> wrote:

When running a playbook with *serial* the *play_hosts* variable includes the hosts just of the current batch. I think this is unexpected and can lead to various issues, especially with the cases where *play_hosts* is generally used (from docs: "This may be useful for filling out templates with multiple hostnames or for injecting the list into the rules for a load balancer"). Is this classified as a bug or known feature?

It seems this is related to the fact that *run_once* tasks in a *serial* play are run once per host batch.

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[Brian Coca]

Yeah, I did not account for 'serial' when i added this, but we want to
add 2 vars to reflect with and without serial behaviors.


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Brian Coca

[Ivaylo Bratoev]

Thanks for the answer Brian,
2 vars sounds like a good solution. Do you want me to open a GitHub issue for that? Would you accept a PR for that?

I was thinking a bit about naming the variables and here are some thoughts:

I see play_hosts is being replaced by ansible_play_hosts but ansible_play_hosts is not documented and (hopefully) not widely used. So what do you think about these names:
ansible_play_hosts - all hosts in the play;
ansible_play_batch_hosts (or ansible_serial_batch_hosts or ansible_batch_hosts) - all hosts in the current play batch.

Additionally, what do you think about the run_once issue - together with serial run_once runs once for each batch which again is unexpected? In the general case this is not a critical issue as executing run_once multiple times should work fine if your task is truly idempotent. In the same time, it is good to be able to run a task once *really* per play; not per batch. You never know how Ansible can be (mis)used ;)

[Brian Coca]

run_once is per batch and was always intended that way, as per naming
the vars, I believe there is already some code doing that, need to x2
check.



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Brian Coca

[Marc Abramowitz]

Did these variables ever get implemented? My googling for ansible_play_hosts found almost nothing.

[Brian Coca]

ansible_play_hosts is in the code base, but we never assign it, so not
yet implemented, though the intention was there.


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Brian Coca