For the complete documentation index, see llms.txt. Markdown versions of all docs pages are available by appending .md to any docs URL.

Advanced settings

You can update several installation settings in your Helm values file. For example, you can update the namespace, set resource limits and requests, or enable extensions such as for AI.

Set the version you want to configure in an environment variable, such as the latest patch version (2.3.6).

export NEW_VERSION=2.3.6

• Show all values:

  helm show values oci://cr.kgateway.dev/kgateway-dev/charts/kgateway --version v$NEW_VERSION

• Get a file with all values: You can get a kgateway/values.yaml file for the upgrade version by pulling and inspecting the Helm chart locally.

  helm pull oci://cr.kgateway.dev/kgateway-dev/charts/kgateway --version v$NEW_VERSION
  tar -xvf kgateway-v$NEW_VERSION.tgz
  open kgateway/values.yaml

For more information, see the Helm reference docs.

Development builds

When using the development build 2.4.0-main, add --set controller.image.pullPolicy=Always to ensure you get the latest image. For production environments, this setting is not recommended as it might impact performance.

Experimental Gateway API features

The KGW_ENABLE_EXPERIMENTAL_GATEWAY_API_FEATURES feature gate controls support for experimental Gateway API features such as the following:

• TCPRoutes
• TLSRoutes
• ListenerSets
• CORS policies
• Retries
• Session persistence

In kgateway version 2.2 and later, this setting defaults to true, so experimental features are enabled by default and no additional configuration is required. To disable these features, set the environment variable to false in your kgateway controller deployment in your Helm values file.

controller:
  extraEnv:
    KGW_ENABLE_EXPERIMENTAL_GATEWAY_API_FEATURES: "false"

Leader election

Leader election is enabled by default to ensure that you can run kgateway in a multi-control plane replica setup for high availability.

You can disable leader election by setting the KGW_DISABLE_LEADER_ELECTION environment variable to "true" through the controller.extraEnv Helm value.

controller:
  extraEnv:
    KGW_DISABLE_LEADER_ELECTION: "true"

Namespace discovery

You can limit the namespaces that kgateway watches for gateway configuration. For example, you might have a multi-tenant cluster with different namespaces for different tenants. You can limit kgateway to only watch a specific namespace for gateway configuration.

Namespace selectors are a list of matched expressions or labels.

• matchExpressions: Use this field for more complex selectors where you want to specify an operator such as In or NotIn.
• matchLabels: Use this field for simple selectors where you want to specify a label key-value pair.

Each entry in the list is disjunctive (OR semantics). This means that a namespace is selected if it matches any selector.

You can also use matched expressions and labels together in the same entry, which is conjunctive (AND semantics).

The following example selects namespaces for discovery that meet either of the following conditions:

• The namespace has the label environment=prod and the label version=v2, or
• The namespace has the label version=v3

discoveryNamespaceSelectors:
- matchExpressions:
  - key: environment
    operator: In
    values:
    - prod
  matchLabels:
    version: v2
- matchLabels:
    version: v3

TLS encryption

You can enable TLS encryption for the xDS gRPC server in the kgateway control plane. For more information, see the TLS encryption docs.

Strict validation

Kgateway supports two validation modes for routes and policies in the control plane: standard and strict. The validation mode controls how the control plane handles invalid configuration before it is sent to Envoy.

Validation modes

Kgateway supports the following validation modes. The mode is set globally on the controller through a single Helm value.

standard mode is the default and is appropriate for most production environments. strict mode is recommended when you cannot tolerate a NACKed xDS update reaching the data plane; for example, you might have downstream automation that depends on every accepted change being safe.

Enable strict validation

Set the validation.level Helm value to strict when you install or upgrade kgateway. Restart the control plane to apply the change.

validation:
  level: strict

Internally, the Helm chart passes the value to the control plane through the KGW_VALIDATION_MODE environment variable. If you manage the control plane deployment manually, set KGW_VALIDATION_MODE=STRICT on the kgateway container.

The accepted values for validation.level are standard and strict (case-insensitive). Any other value causes the Helm install to fail.

Verify the validation mode

To check which mode is active, inspect the KGW_VALIDATION_MODE environment variable on the kgateway controller deployment. The expected output is standard or strict.

kubectl -n kgateway-system get deployment kgateway \
  -o jsonpath='{.spec.template.spec.containers[*].env[?(@.name=="KGW_VALIDATION_MODE")].value}'

Transformation policies and strict validation

Strict validation runs the preflight against an Envoy binary that is bundled in the kgateway control plane image. The control plane image is built from the envoy-wrapper image, which bundles the rustformation dynamic module, and the validator sets ENVOY_DYNAMIC_MODULES_SEARCH_PATH=/usr/local/lib before invoking the preflight. As a result, the preflight understands rustformation per-route config and can validate TrafficPolicies that use transformation.

For more information about transformation engines, see Transformation engines.

ReferenceGrant enforcement modes

In multi-tenant clusters, different teams typically own separate namespaces and share a gateway. The Gateway API ReferenceGrant mechanism controls which cross-namespace references are permitted, ensuring that one team cannot silently access another team’s resources. Without a ReferenceGrant in the target namespace, the reference is denied.

In kgateway, you can configure how strictly you want ReferenceGrant requirements to be enforced by using the KGW_REFERENCE_GRANT_MODE environment variable on the control plane. You can choose between the following modes:

• STRICT: Enforce ReferenceGrants for all cross-namespace references. This mode provides the strongest namespace isolation and is recommended for new clusters.
• PERMISSIVE (default): Enforce ReferenceGrants for BackendRef and SecretRef references, but not for cross-namespace ExtensionRef references. Before reference grant modes were introduced, TrafficPolicy resources were able to reference and access a GatewayExtension resource in another namespace without a ReferenceGrant. PERMISSIVE mode allows these setups to function as before. Over time, you can add the missing ReferenceGrant resources in the required namespaces and migrate your cluster to STRICT ReferenceGrant validation.
• OFF: Disable all ReferenceGrant validation. Not recommended for multi-tenant or production environments.

  Caution

  Do not use OFF in multi-tenant or production environments. It breaks Gateway API compliance, bypasses namespace isolation, and lets any namespace access backends, secrets, and GatewayExtensions in other namespaces without restriction.

Reference validation by mode

The following table shows which cross-namespace references are checked in each mode. Same-namespace references always pass, regardless of the mode.

Enable STRICT mode

1. Check which mode is currently active by inspecting the KGW_REFERENCE_GRANT_MODE environment variable on the controller deployment. If the variable is not set, the active mode is PERMISSIVE.

   kubectl -n kgateway-system get deployment kgateway \
     -o jsonpath='{.spec.template.spec.containers[*].env[?(@.name=="KGW_REFERENCE_GRANT_MODE")].value}'

2. Make sure that any existing cross-namespace TrafficPolicy → GatewayExtension references have a corresponding ReferenceGrant.

3. Get the current Helm values for your kgateway release and save them to a file.

   helm get values kgateway -n kgateway-system -o yaml > values.yaml
   open values.yaml

4. Add the following values to enable STRICT ReferenceGrant validation.

   controller:
     extraEnv:
       KGW_REFERENCE_GRANT_MODE: "STRICT"

5. Apply the change by upgrading the Helm release.

   helm upgrade -i -n kgateway-system kgateway \
     oci://cr.kgateway.dev/kgateway-dev/charts/kgateway \
     --version 2.3.6 \
     -f values.yaml

6. Confirm that the kgateway control plane restarted and is running.

   kubectl get pods -n kgateway-system

7. Verify the active mode.

   kubectl -n kgateway-system get deployment kgateway  \
     -o jsonpath='{.spec.template.spec.containers[*].env[?(@.name=="KGW_REFERENCE_GRANT_MODE")].value}'

Common labels

Add custom labels to all resources that are created by the Helm charts, including the Deployment, Service, ServiceAccount, and ClusterRoles. This allows you to better organize your resources or integrate with external tooling.

The following snippet adds the label-key and kgw-managed labels to all resources.

commonLabels: 
  label-key: label-value
  kgw-managed: "true"

Topology spread constraints

Use topology spread constraints to control how kgateway controller pods are distributed across failure domains such as zones or nodes. This setup helps improve availability and resilience by preventing all replicas from landing in the same zone or node.

For more information, see the Kubernetes topology spread constraints documentation.

The following example spreads controller pods evenly across availability zones, and prevents scheduling if the skew cannot be satisfied.

topologySpreadConstraints:
  - maxSkew: 1
    topologyKey: topology.kubernetes.io/zone
    whenUnsatisfiable: DoNotSchedule
    labelSelector:
      matchLabels:
        app.kubernetes.io/name: kgateway

PriorityClass

You can assign a PriorityClassName to the control plane pods by using the Helm chart. Priority indicates the importance of a pod relative to other pods. If a pod cannot be scheduled, the scheduler tries to preempt (evict) lower priority pods to make scheduling of the pending pod possible.

To assign a PriorityClassName to the control plane, you must first create a PriorityClass resource. The following example creates a PriorityClass with the name system-cluster-critical that assigns a priority of 1 million.

kubectl apply -f- <<EOF
apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: system-cluster-critical
value: 1000000
globalDefault: false
description: "Use this priority class on system-critical pods only."
EOF

In your Helm values file, add the name of the PriorityClass in the controller.priorityClassName field.

controller: 
  priorityClassName: 

Autoscaling

You can configure Horizontal Pod Autoscaler (HPA) or Vertical Pod Autoscaler (VPA) policies for the kgateway control plane. To set up these policies, you use the horizontalPodAutoscaler or verticalPodAutoscaler fields in the Helm chart.

Vertical Pod Autoscaler (VPA)

Vertical Pod Autoscaler (VPA) is a Kubernetes component that automatically adjusts the CPU and memory reservations of your pods to match their actual usage.

The following Helm configuration ensures that the control plane pod is always assigned a minimum of 0.1 CPU cores (100millicores) and 128Mi of memory.

controller:
  verticalPodAutoscaler:
    updatePolicy:
      updateMode: Auto
    resourcePolicy:
      containerPolicies:
      - containerName: "*"
        minAllowed:
          cpu: 100m
          memory: 128Mi

Horizontal Pod Autoscaler (HPA)

Horizontal Pod Autoscaler (HPA) adds more instances of the pod to your environment when certain memory or CPU thresholds are reached.

In the following example, you want to have 1 control plane replica running at any given time. If the CPU utilization averages 80%, you want to gradually scale up your replicas. You can have a maximum of 5 replicas at any given time.

controller: 
  horizontalPodAutoscaler:
    minReplicas: 1
    maxReplicas: 5
    metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 80

Note: To monitor the memory and CPU threshold, you must deploy the Kubernetes metrics-server to your cluster. The metrics-server retrieves metrics, such as CPU and memory consumption, for your workloads.

You can install the server with the following command:

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
kubectl -n kube-system patch deployment metrics-server \
 --type=json \
 -p='[{"op":"add","path":"/spec/template/spec/containers/0/args/-","value":"--kubelet-insecure-tls"}]'

Then, start monitoring CPU and memory consumption with the kubectl top pod command.

PodDisruptionBudget

Configure a Pod Disruption Budget to ensure that a minimum number of control plane instances are up and running at any given time during voluntary disruptions, such as upgrades. In this example, 50% of your control plane instances must be running.

controller: 
  podDisruptionBudget:
    minAvailable: 50%

xDS first-connect grace period

By default, the control plane waits 1 second after a new proxy connects before sending its first xDS snapshot. This gives per-client translation time to converge and prevents newly started gateway pods from receiving incomplete configuration after a controller restart.

You can adjust the grace period by using the KGW_XDS_FIRST_CONNECT_DELAY environment variable on the controller. The value is a Go duration string, for example 2s. Set it to 0 to disable the grace period entirely.

controller:
  extraEnv:
    KGW_XDS_FIRST_CONNECT_DELAY: "2s"