fix(aws-network-mcp-server): detect_tgw_inspection KeyError on VpcId#4291
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arimu1 wants to merge 2 commits into
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fix(aws-network-mcp-server): detect_tgw_inspection KeyError on VpcId#4291arimu1 wants to merge 2 commits into
arimu1 wants to merge 2 commits into
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list_firewalls() only returns FirewallName/FirewallArn, never VpcId, so any account with at least one AWS Network Firewall made detect_tgw_inspection() crash with KeyError: 'VpcId' regardless of the Transit Gateway's attachment mix. VpcId is only available from describe_firewall(), so look it up there instead. Closes awslabs#4286
arimu1
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a team,
NetDevAutomate and
juhala-aws
as code owners
July 21, 2026 02:25
test_vpc_firewall_detection already fails pre-fix now that sample_firewalls matches the real ListFirewalls shape (no VpcId), so the separate no_vpc_id regression test duplicated it with a one-off inline dict. Drop it in favor of the existing test carrying regression coverage. Also convert _describe_firewall_side_effect from a staticmethod to a fixture, matching every other shared value in this test class.
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Summary
detect_tgw_inspectionraised an unhandledKeyError: 'VpcId'any time the account/region had at least one AWS Network Firewall — regardless of the Transit Gateway's attachment mix.Root cause:
nfw_client.list_firewalls()['Firewalls']items only ever containFirewallName/FirewallArn/TransitGatewayAttachmentId(see the ListFirewalls API reference) —VpcIdis never present there.VpcIdonly shows up in the DescribeFirewall response. The unguardedfw['VpcId']access at line 68 ofdetect_transit_gateway_inspection.pytherefore failed on every call that returned any firewalls, independent of the TGW's attachment types — the TGW-attachment filtering code (ResourceType/ResourceId) was already correct and unaffected.Fix
Look up each listed firewall's
VpcIdviadescribe_firewall()(the same call already used a few lines down for TGW network-function attachments), guarding with.get('VpcId')so non-VPC firewalls or describe failures degrade gracefully instead of crashing the whole tool call.Closes #4286
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Test plan
test_vpc_firewall_detection_no_vpc_id_on_list_firewalls) that mockslist_firewalls()with the real API shape (noVpcId) and asserts the tool still correctly finds the VPC-attached firewall viadescribe_firewall().list_firewalls()returnsVpcId.ToolError: Error detecting firewall attachments: 'VpcId'.) against the pre-fix code, and passes after the fix.uv run pytest tests/— 245 passeduv run ruff check/uv run ruff format --checkon changed files — clean