[PR #929/0b97186c backport][stable-4] elbv2 - Fix KeyError when passing two TGs

changelogs/fragments/1089-elb_application_lb-ForwardConfig-KeyError.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- elb_application_lb - fix ``KeyError`` when balancing across two Target Groups (https://github.com/ansible-collections/community.aws/issues/1089).

plugins/module_utils/elbv2.py

@@ -23,14 +23,30 @@
 
 # ForwardConfig may be optional if we've got a single TargetGroupArn entry
 def _prune_ForwardConfig(action):
-    if "ForwardConfig" in action and action['Type'] == 'forward':
-        if action["ForwardConfig"] == {
-                'TargetGroupStickinessConfig': {'Enabled': False},
-                'TargetGroups': [{"TargetGroupArn": action["TargetGroupArn"], "Weight": 1}]}:
-            newAction = action.copy()
-            del(newAction["ForwardConfig"])
-            return newAction
-    return action
+    """
+    Drops a redundant ForwardConfig where TargetGroupARN has already been set.
+    (So we can perform comparisons)
+    """
+    if action.get('Type', "") != 'forward':
+        return action
+    if "ForwardConfig" not in action:
+        return action
+    # Where we have multiple TGs, action['TargetGroupArn'] shouldn't be set
+    if "TargetGroupArn" not in action:
+        return action
+
+    # This is the same as having TargetGroupArn set
+    equivalent_action = {
+        'TargetGroupStickinessConfig': {'Enabled': False},
+        'TargetGroups': [{"TargetGroupArn": action["TargetGroupArn"], "Weight": 1}],
+    }
+    if action["ForwardConfig"] != equivalent_action:
+        return action
+
+    # Remove the redundant ForwardConfig
+    newAction = action.copy()
+    del(newAction["ForwardConfig"])
+    return newAction
 
 
 # the AWS api won't return the client secret, so we'll have to remove it

tests/unit/module_utils/test_elbv2.py

@@ -27,13 +27,34 @@
     }
 ]
 
+one_action_two_tg = [
+    {
+        "ForwardConfig": {
+            "TargetGroupStickinessConfig": {"Enabled": False},
+            "TargetGroups": [
+                {
+                    "TargetGroupArn": "arn:aws:elasticloadbalancing:us-east-1:966509639900:targetgroup/my-tg-58045486/5b231e04f663ae21",
+                    "Weight": 1,
+                },
+                {
+                    "TargetGroupArn": "arn:aws:elasticloadbalancing:us-east-1:966509639900:targetgroup/my-tg-dadf7b62/be2f50b4041f11ed",
+                    "Weight": 1,
+                }
+            ],
+        },
+        "Type": "forward",
+    }
+]
+
 
 def test__prune_ForwardConfig():
     expectation = {
         "TargetGroupArn": "arn:aws:elasticloadbalancing:us-east-1:966509639900:targetgroup/my-tg-58045486/5b231e04f663ae21",
         "Type": "forward",
     }
     assert elbv2._prune_ForwardConfig(one_action[0]) == expectation
+    # https://github.com/ansible-collections/community.aws/issues/1089
+    assert elbv2._prune_ForwardConfig(one_action_two_tg[0]) == one_action_two_tg[0]
 
 
 def _prune_secret():