Backport of (apigw/httproute) Add support to disable traffic with weight 0 in services into release/1.22.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #23216 to be assessed for backporting due to the inclusion of the label backport/1.22.

The below text is copied from the body of the original PR.

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Description

This PR fixes Consul API Gateway behavior for Kubernetes HTTPRoute backends with weight: 0.

Previously, HTTPRoute normalization converted all weight <= 0 values to 1, which caused explicit weight: 0 backends to still receive traffic. This conflicted with Gateway API expectations and customer-observed behavior.

This change updates normalization logic to:

• Preserve explicit weight: 0 (so zero-weight backends can be excluded from traffic).
• Continue normalizing negative weights to 1.

Links

• Prior related fix: GH-16512
• Kubernetes Gateway API backendRefs.weight semantics: Gateway API HTTPRoute spec

Tests

• With this fix, the routes support definition of 0 weight services.
• The instance with weight: 0 does not receive any traffic.

HTTPRoute config output

$ consul config read -kind http-route -name quill-route

{
    "Kind": "http-route",
    "Name": "quill-route",
    "Parents": [
        {
            "Kind": "api-gateway",
            "Name": "api-gateway",
            "SectionName": "http-listener"
        }
    ],
    "Rules": [
        {
            "Filters": {
                "Headers": null,
                "URLRewrite": null,
                "RetryFilter": null,
                "TimeoutFilter": null,
                "JWT": null
            },
            "ResponseFilters": {
                "Headers": null
            },
            "Matches": [
                {
                    "Headers": null,
                    "Method": "",
                    "Path": {
                        "Match": "prefix",
                        "Value": "/"
                    },
                    "Query": null
                }
            ],
            "Services": [
                {
                    "Name": "quill-v1",
                    "Weight": 0,
                    "Filters": {
                        "Headers": null,
                        "URLRewrite": null,
                        "RetryFilter": null,
                        "TimeoutFilter": null,
                        "JWT": null
                    },
                    "ResponseFilters": {
                        "Headers": null
                    }
                },
                {
                    "Name": "quill-v2",
                    "Weight": 100,
                    "Filters": {
                        "Headers": null,
                        "URLRewrite": null,
                        "RetryFilter": null,
                        "TimeoutFilter": null,
                        "JWT": null
                    },
                    "ResponseFilters": {
                        "Headers": null
                    }
                }
            ]
        }
    ],
    "Hostnames": null,
    "CreateIndex": 43,
    "ModifyIndex": 80,
    "Status": {
        "Conditions": [
            {
                "Type": "Accepted",
                "Status": "True",
                "Reason": "Accepted",
                "Message": "route is valid",
                "Resource": {
                    "Kind": "",
                    "Name": "",
                    "SectionName": ""
                },
                "LastTransitionTime": "2026-02-16T08:17:57.943208Z"
            },
            {
                "Type": "Bound",
                "Status": "True",
                "Reason": "Bound",
                "Message": "successfully bound route",
                "Resource": {
                    "Kind": "api-gateway",
                    "Name": "api-gateway",
                    "SectionName": "http-listener"
                },
                "LastTransitionTime": "2026-02-16T08:17:57.943215Z"
            }
        ]
    }
}

Traffic Distribution

case 1:

Services = [
  {
    Name = "quill-v1"
    Weight = 100
  },
  {
    Name = "quill-v2"
    Weight = 100
  }
]

case 2:

Services = [
  {
    Name = "quill-v1"
    Weight = 0
  },
  {
    Name = "quill-v2"
    Weight = 100
  }
]

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.

• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.

• If applicable, I've documented the impact of any changes to security controls.

  Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

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Overview of commits

• 31e303c

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR