From 4df129c6ae3c5f33fccd7e70ccb629610af60dfb Mon Sep 17 00:00:00 2001
From: Martin Krizek <martin.krizek@gmail.com>
Date: Mon, 28 Sep 2020 07:34:38 +0200
Subject: [PATCH] Provide more information in AnsibleUndefinedVariable (#71666)
 (#71876)

* Provide more information in AnsibleUndefinedVariable

Fixes #55152

(cherry picked from commit 00b22ab55ea1b514053ca8a9ba3928bc210ea3aa)
---
 ...-add-more-info-to-AnsibleUndefinedVariable.yml |  2 ++
 lib/ansible/template/vars.py                      |  4 ++--
 test/integration/targets/template/runme.sh        |  3 +++
 .../targets/template/undefined_var_info.yml       | 15 +++++++++++++++
 4 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 changelogs/fragments/55152-add-more-info-to-AnsibleUndefinedVariable.yml
 create mode 100644 test/integration/targets/template/undefined_var_info.yml

diff --git a/changelogs/fragments/55152-add-more-info-to-AnsibleUndefinedVariable.yml b/changelogs/fragments/55152-add-more-info-to-AnsibleUndefinedVariable.yml
new file mode 100644
index 00000000000..a229848bcbf
--- /dev/null
+++ b/changelogs/fragments/55152-add-more-info-to-AnsibleUndefinedVariable.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - Provide more information in AnsibleUndefinedVariable (https://github.com/ansible/ansible/issues/55152)
diff --git a/lib/ansible/template/vars.py b/lib/ansible/template/vars.py
index 164cf1a1abe..464deecf808 100644
--- a/lib/ansible/template/vars.py
+++ b/lib/ansible/template/vars.py
@@ -104,8 +104,8 @@ class AnsibleJ2Vars(Mapping):
             value = None
             try:
                 value = self._templar.template(variable)
-            except AnsibleUndefinedVariable:
-                raise
+            except AnsibleUndefinedVariable as e:
+                raise AnsibleUndefinedVariable("%s: %s" % (to_native(variable), e.message))
             except Exception as e:
                 msg = getattr(e, 'message', None) or to_native(e)
                 raise AnsibleError("An unhandled exception occurred while templating '%s'. "
diff --git a/test/integration/targets/template/runme.sh b/test/integration/targets/template/runme.sh
index 61511ac82f1..8e21352d29b 100755
--- a/test/integration/targets/template/runme.sh
+++ b/test/integration/targets/template/runme.sh
@@ -22,3 +22,6 @@ ansible-playbook filter_plugins.yml -v "$@"
 
 # https://github.com/ansible/ansible/issues/68699
 ansible-playbook unused_vars_include.yml -v "$@"
+
+# https://github.com/ansible/ansible/issues/55152
+ansible-playbook undefined_var_info.yml -v "$@"
diff --git a/test/integration/targets/template/undefined_var_info.yml b/test/integration/targets/template/undefined_var_info.yml
new file mode 100644
index 00000000000..b96a58db142
--- /dev/null
+++ b/test/integration/targets/template/undefined_var_info.yml
@@ -0,0 +1,15 @@
+- hosts: localhost
+  gather_facts: no
+  vars:
+    foo: []
+    bar: "{{ foo[0] }}"
+  tasks:
+    - debug:
+        msg: "{{ bar }}"
+      register: result
+      ignore_errors: yes
+
+    - assert:
+        that:
+          - '"foo[0]" in result.msg'
+          - '"object has no element 0" in result.msg'