Errors can be wrongly replaced on dynamically imported static include

[johnboy2]

ISSUE TYPE

• Bug Report

COMPONENT NAME

include_tasks

ANSIBLE VERSION

ansible 2.4.2.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.12 (default, Nov 20 2017, 18:23:56) [GCC 5.4.0 20160609]

CONFIGURATION

ANSIBLE_PIPELINING(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = True
ANSIBLE_SSH_ARGS(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = -o ControlMaster=auto -o ControlPersist=300s -o UserKnownHostsFile=./ssh_known_hosts
DEFAULT_BECOME(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = True
DEFAULT_LOG_PATH(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = /mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.log
DEFAULT_REMOTE_USER(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = automation
DEFAULT_ROLES_PATH(/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/ansible.cfg) = [u'/mnt/speedyg/johnn/Documents/EclipseWS/cloud-network/roles']

OS / ENVIRONMENT

Management node: Ubuntu 16.04
Remote node: Debian 9

SUMMARY

Untrue/incorrect error message shown when a dynamically-determined dynamic include contains an embedded reference to an unknown file.

STEPS TO REPRODUCE

test.yml:

- hosts: all
  tasks:
  - debug: var=ansible_system
  - include_tasks: '{{ ansible_system }}.yml'

Linux.yml:

- import_tasks: a_file_that_does_not_exist.yml

Execute command:

ansible-playbook -l "pick_an_inventory_host" test.yml

EXPECTED RESULTS

The debug task should execute as expected, showing the remote system's platform (expected in this case to be "Linux").

For the "include_tasks" task, it should result in an error along the lines of:

FAILED! => {"reason": "Unable to retrieve file contents\nCould not find or access '...'"}

(which is what you get with a straight-up static include of a missing file)

ACTUAL RESULTS

Debug task executes as expected (which also proves that ansible_system is defined).

The "import_tasks" task fails, as expected, but does so with an entirely incorrect error message:

FAILED! => {"reason": "'ansible_system' is undefined"}

Ansible thus hides the actual fault in this case behind a completely false error.

[ansibot]

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[johnboy2]

!component +modules/utilities/logic/include_tasks.py

[sivel]

!component +lib/ansible/modules/utilities/logic/include_tasks.py
!component +lib/ansible/plugins/callback/default.py

[sivel]

This actually has nothing to do with a_file_that_does_not_exist.yml not existing.

The problem is that, in order for a relatively pathed included file to be found, we look at the file of the parent include, to ensure we start with the correct directory.

In this case, the path of the parent include is defined as {{ ansible_system }}.yml. Because that contains a variable, we then try to template it.

When we try to template it in ansible.playbook.helpers.load_list_of_tasks we no longer have host context, and as such, we cannot template ansible_system as we have no record of that variable.

If we were to have defined ansible_system in another way, we would have gotten an error indicating that a_file_that_does_not_exist.yml does not exist.

!component -lib/ansible/plugins/callback/default.py
!component +lib/ansible/playbook/helpers.py

[sivel]

A not so correct solution, but a solution nonetheless:

diff --git a/lib/ansible/playbook/helpers.py b/lib/ansible/playbook/helpers.py
index 248a840bb0..6518ace88f 100644
--- a/lib/ansible/playbook/helpers.py
+++ b/lib/ansible/playbook/helpers.py
@@ -178,7 +178,10 @@ def load_list_of_tasks(ds, play, block=None, role=None, task_include=None, use_h
                         if not isinstance(parent_include, TaskInclude):
                             parent_include = parent_include._parent
                             continue
-                        parent_include_dir = os.path.dirname(templar.template(parent_include.args.get('_raw_params')))
+                        try:
+                            parent_include_dir = os.path.dirname(templar.template(parent_include.args.get('_raw_params')))
+                        except AnsibleUndefinedVariable:
+                            parent_include_dir = ''
                         if cumulative_path is None:
                             cumulative_path = parent_include_dir
                         elif not os.path.isabs(cumulative_path):

Ideally we would have to implement some form of path inheritance that didn't depend on host context. Which would mean every consolidated include result, would need a unique parent with vars pre-resolved for later.

That isn't a fix that is simple, and not something that can make it into 2.6.

The above fix just does the best we can, and assumes that the included file is immediately relative.

[sivel]

Resolved in #39365