1 files changed, 113 insertions, 0 deletions
diff --git a/src/ansiblelint/rules/loop_var_prefix.py b/src/ansiblelint/rules/loop_var_prefix.py
new file mode 100644
index 0000000..8f1bb56
--- /dev/null
+++ b/src/ansiblelint/rules/loop_var_prefix.py
@@ -0,0 +1,113 @@
+"""Optional Ansible-lint rule to enforce use of prefix on role loop vars."""
+from __future__ import annotations
+
+import re
+import sys
+from typing import TYPE_CHECKING
+
+from ansiblelint.config import LOOP_VAR_PREFIX, options
+from ansiblelint.rules import AnsibleLintRule
+from ansiblelint.text import toidentifier
+
+if TYPE_CHECKING:
+    from ansiblelint.errors import MatchError
+    from ansiblelint.file_utils import Lintable
+    from ansiblelint.utils import Task
+
+
+class RoleLoopVarPrefix(AnsibleLintRule):
+    """Role loop_var should use configured prefix."""
+
+    id = "loop-var-prefix"
+    link = (
+        "https://docs.ansible.com/ansible/latest/playbook_guide/"
+        "playbooks_loops.html#defining-inner-and-outer-variable-names-with-loop-var"
+    )
+    description = """\
+Looping inside roles has the risk of clashing with loops from user-playbooks.\
+"""
+
+    tags = ["idiom"]
+    prefix = re.compile("")
+    severity = "MEDIUM"
+    _ids = {
+        "loop-var-prefix[wrong]": "Loop variable name does not match regex.",
+        "loop-var-prefix[missing]": "Replace unsafe implicit `item` loop variable.",
+    }
+
+    def matchtask(
+        self,
+        task: Task,
+        file: Lintable | None = None,
+    ) -> list[MatchError]:
+        """Return matches for a task."""
+        if not file or not file.role or not options.loop_var_prefix:
+            return []
+
+        self.prefix = re.compile(
+            options.loop_var_prefix.format(role=toidentifier(file.role)),
+        )
+        has_loop = "loop" in task.raw_task
+        for key in task.raw_task:
+            if key.startswith("with_"):
+                has_loop = True
+
+        if has_loop:
+            loop_control = task.raw_task.get("loop_control", {})
+            loop_var = loop_control.get("loop_var", "")
+
+            if loop_var:
+                if not self.prefix.match(loop_var):
+                    return [
+                        self.create_matcherror(
+                            message=f"Loop variable name does not match /{options.loop_var_prefix}/ regex, where role={toidentifier(file.role)}.",
+                            filename=file,
+                            tag="loop-var-prefix[wrong]",
+                        ),
+                    ]
+            else:
+                return [
+                    self.create_matcherror(
+                        message=f"Replace unsafe implicit `item` loop variable by adding a `loop_var` that is matching /{options.loop_var_prefix}/ regex.",
+                        filename=file,
+                        tag="loop-var-prefix[missing]",
+                    ),
+                ]
+
+        return []
+
+
+# testing code to be loaded only with pytest or when executed the rule file
+if "pytest" in sys.modules:
+    import pytest
+
+    from ansiblelint.rules import RulesCollection  # pylint: disable=ungrouped-imports
+    from ansiblelint.runner import Runner  # pylint: disable=ungrouped-imports
+
+    @pytest.mark.parametrize(
+        ("test_file", "failures"),
+        (
+            pytest.param(
+                "examples/playbooks/roles/loop_var_prefix/tasks/pass.yml",
+                0,
+                id="pass",
+            ),
+            pytest.param(
+                "examples/playbooks/roles/loop_var_prefix/tasks/fail.yml",
+                6,
+                id="fail",
+            ),
+        ),
+    )
+    def test_loop_var_prefix(
+        default_rules_collection: RulesCollection,
+        test_file: str,
+        failures: int,
+    ) -> None:
+        """Test rule matches."""
+        # Enable checking of loop variable prefixes in roles
+        options.loop_var_prefix = LOOP_VAR_PREFIX
+        results = Runner(test_file, rules=default_rules_collection).run()
+        for result in results:
+            assert result.rule.id == RoleLoopVarPrefix().id
+        assert len(results) == failures