Add format_dict filter

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 100

.gitignore

@@ -1,3 +1,5 @@
+**/__pycache__/**
+.coverage
 fact_cache/**
 group_vars/**
 host_vars/**

ansible.cfg

@@ -1,7 +1,10 @@
 [defaults]
 gathering = smart
+
 fact_caching = ansible.builtin.jsonfile
 fact_caching_connection = fact_cache
 
+filter_plugins = plugins/filter
+
 [privilege_escalation]
 become = True

ci-requirements.txt

@@ -0,0 +1,6 @@
+ansible
+ansible-lint
+pytest
+pytest-cov
+flake8
+yamllint

makefile

@@ -0,0 +1,10 @@
+ci-requirements:
+	@python -m pip install --upgrade -r ci-requirements.txt
+
+plugins-test:
+	@python -m pytest -vv --cov plugins/filter --cov-report=term-missing plugins/tests
+
+plugins-lint:
+	@python -m flake8 plugins
+
+.PHONY: ci-requirements plugins-test plugins-lint

plugins/filter/format.py

@@ -0,0 +1,32 @@
+import jinja2.exceptions
+import ansible.errors
+import ansible.module_utils
+
+
+def __format_dict(dict_, pattern, *args):
+    values = []
+    for arg in args:
+        keys = arg.split(".")
+        value = dict_
+        for i, key in enumerate(keys):
+            try:
+                value = value[key]
+            except KeyError:
+                raise KeyError(f"{key} not in {'.'.join(['item'] + keys[:i])}")
+        values.append(value)
+    return pattern.format(*values)
+
+
+def format_dict(dict_, pattern, *args):  # pragma: no cover
+    try:
+        return __format_dict(dict_, pattern, *args)
+    except jinja2.exceptions.UndefinedError as e:
+        raise ansible.errors.AnsibleUndefinedVariable(
+            ansible.module_utils._text.to_native(e)) from e
+    except Exception as e:
+        raise ansible.errors.AnsibleFilterError(ansible.module_utils._text.to_native(e)) from e
+
+
+class FilterModule:  # pragma: no cover
+    def filters(self):
+        return {"format_dict": format_dict}

plugins/tests/test_filter.py

@@ -0,0 +1,43 @@
+import ansible.errors
+import pytest
+
+from plugins.filter.format import format_dict
+
+
+@pytest.fixture()
+def item():
+    return {
+        "key": "key_value",
+        "value": {
+            "key_2_1": "value_2_1",
+            "key_2_2": {
+                "key_2_2_1": "value_2_2_1",
+                "key_2_2_2": "value_2_2_2",
+            },
+            "key_2_3": {
+                "key_2_3_1": "value_2_3_1",
+            },
+        },
+    }
+
+
+def test_format_dict(item):
+    string = format_dict(
+        item,
+        "start-{}-{}-{}-end",
+        "key",
+        "value.key_2_1",
+        "value.key_2_2.key_2_2_2",
+    )
+    assert string == "start-key_value-value_2_1-value_2_2_2-end"
+
+
+def test_format_dict_key_error(item):
+    with pytest.raises(ansible.errors.AnsibleFilterError):
+        format_dict(
+            item,
+            "start-{}-{}-{}-end",
+            "key",
+            "value.key_2_1",
+            "value.key_2_2.key_2_3_1",
+        )