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Merge pull request #93 from kgateway-dev/issue_59_12
agentgateway emitter: map body-size annotations to frontend HTTP buffer
2 parents 158809c + 1ea2174 commit e14c2b3

6 files changed

Lines changed: 206 additions & 9 deletions

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‎pkg/i2gw/emitters/agentgateway/README.md‎

Lines changed: 18 additions & 1 deletion
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@@ -398,13 +398,30 @@ This is projected into a **Service-targeted** `AgentgatewayPolicy` by setting:
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- The provider currently maps only gRPC-family values into policy IR, so the agentgateway emitter currently emits
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only `HTTP2` for this feature.
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#### Request/Body Buffer Size
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The agentgateway emitter supports projecting ingress-nginx request/body size controls via:
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- `nginx.ingress.kubernetes.io/proxy-body-size`
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- `nginx.ingress.kubernetes.io/client-body-buffer-size`
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These are projected into an `AgentgatewayPolicy` by setting:
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- `AgentgatewayPolicy.spec.frontend.http.maxBufferSize`
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**Semantics:**
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- `proxy-body-size` is preferred when both annotations are present.
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- `client-body-buffer-size` is used as a fallback when `proxy-body-size` is unset.
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- The selected quantity is resolved to bytes for `maxBufferSize`.
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401418
## AgentgatewayPolicy Projection
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Rate limit, timeout, CORS, rewrite target, access log, etc. annotations are converted into AgentgatewayPolicy resources.
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The agentgateway emitter emits AgentgatewayPolicy resources in two shapes:
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- HTTPRoute-scoped policies for traffic-level behavior (rate limit, request timeouts, CORS, rewrite target,
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basic auth, ext auth, access log).
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basic auth, ext auth, access log, request/body buffer size).
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- Service-scoped policies for backend connection behavior (backend TLS, proxy connect timeout, backend protocol).
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### Naming

‎pkg/i2gw/emitters/agentgateway/buffer.go‎

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@@ -0,0 +1,77 @@
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/*
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Copyright 2025 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package agentgateway
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import (
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"fmt"
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"math"
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emitterir "github.com/kgateway-dev/ingress2gateway/pkg/i2gw/emitter_intermediate"
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agentgatewayv1alpha1 "github.com/kgateway-dev/kgateway/v2/api/v1alpha1/agentgateway"
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"k8s.io/apimachinery/pkg/util/validation/field"
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)
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// applyBufferPolicy projects ingress-nginx body-size annotations into
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// AgentgatewayPolicy.spec.frontend.http.maxBufferSize.
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//
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// Semantics:
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// - Prefer proxy-body-size when set.
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// - Otherwise fall back to client-body-buffer-size.
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func applyBufferPolicy(
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pol emitterir.Policy,
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ingressName, namespace string,
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ap map[string]*agentgatewayv1alpha1.AgentgatewayPolicy,
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) (bool, *field.Error) {
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if pol.ProxyBodySize == nil && pol.ClientBodyBufferSize == nil {
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return false, nil
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}
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size := pol.ProxyBodySize
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if size == nil {
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size = pol.ClientBodyBufferSize
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}
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if size == nil {
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return false, nil
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}
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sizeBytes := size.Value()
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if sizeBytes <= 0 {
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return false, field.Invalid(
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field.NewPath("emitter", "agentgateway", "AgentgatewayPolicy", "frontend", "http", "maxBufferSize"),
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size.String(),
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"resolved maxBufferSize must be greater than 0",
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)
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}
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if sizeBytes > math.MaxInt32 {
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return false, field.Invalid(
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field.NewPath("emitter", "agentgateway", "AgentgatewayPolicy", "frontend", "http", "maxBufferSize"),
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size.String(),
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fmt.Sprintf("resolved maxBufferSize exceeds int32 limit (%d)", int64(math.MaxInt32)),
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)
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}
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maxBufferSize := int32(sizeBytes)
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agp := ensureAgentgatewayPolicy(ap, ingressName, namespace)
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if agp.Spec.Frontend == nil {
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agp.Spec.Frontend = &agentgatewayv1alpha1.Frontend{}
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}
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if agp.Spec.Frontend.HTTP == nil {
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agp.Spec.Frontend.HTTP = &agentgatewayv1alpha1.FrontendHTTP{}
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}
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agp.Spec.Frontend.HTTP.MaxBufferSize = &maxBufferSize
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return true, nil
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}

‎pkg/i2gw/emitters/agentgateway/emitter.go‎

Lines changed: 10 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -176,14 +176,16 @@ func (e *Emitter) Emit(ir emitterir.EmitterIR) (i2gw.GatewayResources, field.Err
176176
)
177177
}
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179-
// Buffer policy currently has no equivalent in AgentgatewayPolicy (see README for limitations).
180-
if pol.ProxyBodySize != nil || pol.ClientBodyBufferSize != nil {
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errs = append(errs, field.Invalid(
182-
field.NewPath("emitter", "agentgateway", "AgentgatewayPolicy"),
183-
polSourceIngressName,
184-
"buffer policy (nginx.ingress.kubernetes.io/proxy-body-size/nginx.ingress.kubernetes.io/client-body-buffer-size) "+
185-
"is not supported by the agentgateway emitter",
186-
))
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// Buffer policy maps to AgentgatewayPolicy.spec.frontend.http.maxBufferSize.
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if bufferTouched, bufferErr := applyBufferPolicy(
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pol,
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polSourceIngressName,
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httpRouteKey.Namespace,
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agentgatewayPolicies,
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); bufferErr != nil {
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errs = append(errs, bufferErr)
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} else if bufferTouched {
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touched = true
187189
}
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// Attach the resulting AgentgatewayPolicy to the HTTPRoute, but only if the policy fully covers the route.

‎pkg/i2gw/emitters/agentgateway/emitter_integration_test.go‎

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Original file line numberDiff line numberDiff line change
@@ -441,6 +441,32 @@ func TestAgentgatewayIngressNginxIntegration_AccessLog(t *testing.T) {
441441
}
442442
}
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func TestAgentgatewayIngressNginxIntegration_BufferBodySize(t *testing.T) {
445+
t.Helper()
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tests := []struct {
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name string
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inputRel string
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goldenRel string
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}{
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{
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name: "buffer_body_size",
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inputRel: filepath.Join(
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"pkg", "i2gw", "emitters", "agentgateway", "testing", "testdata", "input", "buffer_body_size.yaml",
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),
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goldenRel: filepath.Join(
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"pkg", "i2gw", "emitters", "agentgateway", "testing", "testdata", "output", "buffer_body_size.yaml",
459+
),
460+
},
461+
}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
465+
runGoldenTest(t, tt.inputRel, tt.goldenRel)
466+
})
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}
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}
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444470
func TestAgentgatewayIngressNginxIntegration_SSLRedirect(t *testing.T) {
445471
t.Helper()
446472

‎pkg/i2gw/emitters/agentgateway/testing/testdata/input/buffer_body_size.yaml‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,21 @@
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apiVersion: networking.k8s.io/v1
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kind: Ingress
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metadata:
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annotations:
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nginx.ingress.kubernetes.io/client-body-buffer-size: "1Mi"
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nginx.ingress.kubernetes.io/proxy-body-size: "2Mi"
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name: ingress-buffer-body-size
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namespace: default
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spec:
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ingressClassName: nginx
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rules:
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- host: buffer-body-size.example.org
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http:
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paths:
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- backend:
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service:
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name: myservice
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port:
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number: 80
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path: /
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pathType: Prefix

‎pkg/i2gw/emitters/agentgateway/testing/testdata/output/buffer_body_size.yaml‎

Lines changed: 54 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,54 @@
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apiVersion: agentgateway.dev/v1alpha1
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kind: AgentgatewayPolicy
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metadata:
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name: ingress-buffer-body-size
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namespace: default
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spec:
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frontend:
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http:
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maxBufferSize: 2097152
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targetRefs:
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- group: gateway.networking.k8s.io
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kind: HTTPRoute
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name: ingress-buffer-body-size-buffer-body-size-example-org
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status:
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ancestors: null
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---
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apiVersion: gateway.networking.k8s.io/v1
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kind: Gateway
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metadata:
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annotations:
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gateway.networking.k8s.io/generator: ingress2gateway-dev
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name: nginx
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namespace: default
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spec:
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gatewayClassName: agentgateway
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listeners:
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- hostname: buffer-body-size.example.org
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name: buffer-body-size-example-org-http
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port: 80
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protocol: HTTP
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status: {}
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---
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apiVersion: gateway.networking.k8s.io/v1
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kind: HTTPRoute
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metadata:
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annotations:
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gateway.networking.k8s.io/generator: ingress2gateway-dev
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name: ingress-buffer-body-size-buffer-body-size-example-org
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namespace: default
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spec:
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hostnames:
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- buffer-body-size.example.org
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parentRefs:
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- name: nginx
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rules:
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- backendRefs:
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- name: myservice
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port: 80
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matches:
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- path:
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type: PathPrefix
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value: /
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status:
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parents: []

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