r/aws_elbv2_listener: fix crash reading forward action

[jar-b]

Description

Adds a check to the flattenLbForwardAction function to verify the default actions attribute is known and not null before checking the length. Previously the length was checked without verifying the attribute was known, potentially resulting in a crash during read operations.

Relations

Closes #39031

Output from Acceptance Testing

% make testacc PKG=elbv2 TESTS=TestAccELBV2Listener_
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.22.6 test ./internal/service/elbv2/... -v -count 1 -parallel 20 -run='TestAccELBV2Listener_'  -timeout 360m

--- PASS: TestAccELBV2Listener_mutualAuthenticationPassthrough (227.28s)
=== CONT  TestAccELBV2Listener_ActionForward_ForwardBlock_AddStickiness
--- PASS: TestAccELBV2Listener_mutualAuthentication (229.83s)
=== CONT  TestAccELBV2Listener_forwardTargetARNAndBlock
--- PASS: TestAccELBV2Listener_oidc (241.32s)
=== CONT  TestAccELBV2Listener_forwardWeighted
--- PASS: TestAccELBV2Listener_ActionForward_TargetGroupARNToForwardBlock_WeightAndStickiness (244.97s)
=== CONT  TestAccELBV2Listener_updateForwardBasic
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlockToTargetGroupARN_NoChanges (246.47s)
=== CONT  TestAccELBV2Listener_disappears
--- PASS: TestAccELBV2Listener_tags_DefaultTags_nullOverlappingResourceTag (249.45s)
=== CONT  TestAccELBV2Listener_Gateway_basic
--- PASS: TestAccELBV2Listener_tags_DefaultTags_emptyProviderOnlyTag (252.40s)
=== CONT  TestAccELBV2Listener_tags_ComputedTag_OnUpdate_Add
--- PASS: TestAccELBV2Listener_DefaultAction_specifyOrder (253.34s)
=== CONT  TestAccELBV2Listener_Application_basic
--- PASS: TestAccELBV2Listener_Protocol_upd (255.67s)
=== CONT  TestAccELBV2Listener_tags_ComputedTag_OnUpdate_Replace
--- PASS: TestAccELBV2Listener_backwardsCompatibility (256.87s)
=== CONT  TestAccELBV2Listener_tags_ComputedTag_OnCreate
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlockToTargetGroupARN_WeightAndStickiness (258.95s)
=== CONT  TestAccELBV2Listener_DefaultAction_defaultOrder
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlock_RemoveStickiness (262.88s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_nullNonOverlappingResourceTag
--- PASS: TestAccELBV2Listener_DefaultAction_actionDisappears (266.71s)
=== CONT  TestAccELBV2Listener_ActionForward_IgnoreFields
--- PASS: TestAccELBV2Listener_ActionForward_TargetGroupARNToForwardBlock_NoChanges (270.91s)
=== CONT  TestAccELBV2Listener_redirect
--- PASS: TestAccELBV2Listener_Network_basic (272.20s)
=== CONT  TestAccELBV2Listener_cognito
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlock_RemoveAction (274.75s)
=== CONT  TestAccELBV2Listener_fixedResponse
--- PASS: TestAccELBV2Listener_tags (275.54s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_providerOnly
--- PASS: TestAccELBV2Listener_Protocol_https (280.82s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_emptyResourceTag
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlock_AddAction (297.53s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_updateToResourceOnly
--- PASS: TestAccELBV2Listener_redirectWithTargetGroupARN (325.95s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_updateToProviderOnly
--- PASS: TestAccELBV2Listener_forwardTargetARNAndBlock (192.93s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_overlapping
--- PASS: TestAccELBV2Listener_Gateway_basic (189.50s)
=== CONT  TestAccELBV2Listener_tags_DefaultTags_nonOverlapping
--- PASS: TestAccELBV2Listener_ActionForward_ForwardBlock_AddStickiness (222.54s)
=== CONT  TestAccELBV2Listener_Protocol_tls
--- PASS: TestAccELBV2Listener_tags_ComputedTag_OnCreate (201.74s)
=== CONT  TestAccELBV2Listener_tags_EmptyTag_OnCreate
--- PASS: TestAccELBV2Listener_Application_basic (207.93s)
=== CONT  TestAccELBV2Listener_tags_EmptyTag_OnUpdate_Replace
--- PASS: TestAccELBV2Listener_updateForwardBasic (220.31s)
=== CONT  TestAccELBV2Listener_tags_EmptyTag_OnUpdate_Add
--- PASS: TestAccELBV2Listener_disappears (224.12s)
=== CONT  TestAccELBV2Listener_tags_AddOnUpdate
--- PASS: TestAccELBV2Listener_tags_DefaultTags_nullNonOverlappingResourceTag (210.19s)
=== CONT  TestAccELBV2Listener_tags_null
--- PASS: TestAccELBV2Listener_DefaultAction_defaultOrder (217.43s)
=== CONT  TestAccELBV2Listener_LoadBalancerARN_gatewayLoadBalancer
--- PASS: TestAccELBV2Listener_tags_ComputedTag_OnUpdate_Add (230.66s)
=== CONT  TestAccELBV2Listener_EmptyDefaultAction/authenticate-cognito
--- PASS: TestAccELBV2Listener_tags_ComputedTag_OnUpdate_Replace (228.55s)
=== CONT  TestAccELBV2Listener_EmptyDefaultAction/authenticate-oidc
=== CONT  TestAccELBV2Listener_EmptyDefaultAction/forward
=== CONT  TestAccELBV2Listener_EmptyDefaultAction/fixed-response
=== CONT  TestAccELBV2Listener_EmptyDefaultAction/redirect
--- PASS: TestAccELBV2Listener_EmptyDefaultAction (0.00s)
    --- PASS: TestAccELBV2Listener_EmptyDefaultAction/authenticate-cognito (1.63s)
    --- PASS: TestAccELBV2Listener_EmptyDefaultAction/authenticate-oidc (1.87s)
    --- PASS: TestAccELBV2Listener_EmptyDefaultAction/forward (1.70s)
    --- PASS: TestAccELBV2Listener_EmptyDefaultAction/fixed-response (1.68s)
    --- PASS: TestAccELBV2Listener_EmptyDefaultAction/redirect (1.61s)
--- PASS: TestAccELBV2Listener_ActionForward_IgnoreFields (221.61s)
--- PASS: TestAccELBV2Listener_redirect (221.82s)
--- PASS: TestAccELBV2Listener_fixedResponse (218.53s)
--- PASS: TestAccELBV2Listener_cognito (227.62s)
--- PASS: TestAccELBV2Listener_forwardWeighted (259.11s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_emptyResourceTag (221.82s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_updateToResourceOnly (257.67s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_updateToProviderOnly (255.03s)
--- PASS: TestAccELBV2Listener_LoadBalancerARN_gatewayLoadBalancer (155.57s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_providerOnly (367.38s)
--- PASS: TestAccELBV2Listener_tags_null (204.67s)
--- PASS: TestAccELBV2Listener_tags_EmptyTag_OnUpdate_Replace (220.60s)
--- PASS: TestAccELBV2Listener_tags_EmptyTag_OnCreate (233.93s)
--- PASS: TestAccELBV2Listener_tags_AddOnUpdate (224.94s)
--- PASS: TestAccELBV2Listener_tags_EmptyTag_OnUpdate_Add (240.76s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_overlapping (307.22s)
--- PASS: TestAccELBV2Listener_tags_DefaultTags_nonOverlapping (310.24s)
--- PASS: TestAccELBV2Listener_Protocol_tls (426.18s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/elbv2      884.767s

[github-actions]

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[ewbankkit]

LGTM 🚀.

[samveen]

@jar-b Thank you for the quick turnaround.

[github-actions]

This functionality has been released in v5.65.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.