open-consul/website/content/docs/api-gateway/configuration/gateway.mdx

---
layout: docs
page_title: Consul API Gateway Gateway
description:  >-
  Consul API Gateway Gateway
---

# Gateway

This topic provides full details about the `Gateway` resource.

## Introduction

A `Gateway` is an instance of network infrastructure that determines how service traffic should be handled. A `Gateway` contains one or more `listeners` that bind to a set of IP addresses. An `HTTPRoute` or `TCPRoute` can then attach to a gateway listener to direct traffic from the gateway to a service.

Gateway instances derive their configurations from the `GatewayClass` resource, which acts as a template for individual `Gateway` deployments. Refer to [GatewayClass](/docs/api-gateway/configuration/gatewayclass) for additional information.

Specify the following parameters to declare a Gateway:

|  Parameter  |                                                                         Description                                                                        | Required |
|:-----------:|:----------------------------------------------------------------------------------------------------------------------------------------------------------:|:--------:|
| kind        | Specifies the type of configuration object. The value should always be Gateway                                                                             | Required |
| description | Human-readable string for describing the purpose of the Gateway.                                                                                           | Optional |
| version     | Specifies the Kubernetes API version. The value should always be gateway.networking.k8s.io/v1alpha2                                                        | Required |
| scope       | Specifies the effective scope of the Gateway. The value should always be namespaced.                                                                       | Required |
| fields      | Specifies the configurations for the Gateway. The fields are listed in the Configuration model. Details for each field are described in the Specification. | Required |



## Configuration model

* gatewayClassName: string | required
* listeners: array of objects | required
  * allowedRoutes: object | required
  * namespaces: object | required
    * from: string | required
    * selector: object | required if from is configured to selector
      * matchExpressions: array of objects | required if matchLabels is not configured
        * key: string | required if matchExpressions is declared
        * operator: string | required if matchExpressions is declared
        * values: array of strings | required if matchExpressions is declared
      * matchLabels: map of strings | required if matchExpressions is not configured
  * hostname: string | required
  * name: string | required
  * port: integer | required
  * protocol: string | required
  * tls: object | required if protocol is set to HTTPS
      * certificateRefs: array or objects | required if tls is declared
        * name: string | required if certificateRefs is declared
        * namespace: string | required if certificateRefs is declared
      * mode: string | required if certificateRefs is declared
      * options: map of strings | optional

## Specification

This topic provides details about the configuration parameters.

### gatewayClassName
Specifies the name of the `GatewayClass` resource used for the `Gateway` instance.
* Type: string
* Required: required

### listeners
Specifies the `listeners` associated with the `Gateway`. At least one `listener` must be specified. Each `listener` within a `Gateway` must have a unique combination of `hostname`, `port`, and `protocol`.

* Type: array of objects
* Required: required

### listeners.allowedRoutes
Specifies a `namespace` object that defines the types of routes that may be attached to a listener.
* Type: object
* Required: required

### listeners.allowedRoutes.namespaces
Determines which routes are allowed to attach to the `listener`. Only routes in the same namespace as the `Gateway` may be attached by default.

### listeners.allowedRoutes.namespaces.from
Specifies the policy for which namespaces a route may attach to a `Gateway` from. Defaults to `Same`.

This parameter has the following properties:
* Type: string
* Required: required

You can specify one of the following strings:
* `All`: Routes in all namespaces may be attached to the `Gateway`.
* `Same`: Only routes in the same namespace as the `Gateway` may be attached.
* `Selector`: Only routes in namespaces that match the `selector` may be attached.

### listeners.allowedRoutes.namespaces.selector
The `selector` configuration matches zero or more namespaces that determine which routes are allowed to attach to the listener.
* Type: Object
* Required: Required when from is configured to selector.

The selector configuration contains one of the following objects:
* `matchExpressions`
* `matchLabels`

### listeners.allowedRoutes.namespaces.selector.matchExpressions
Specifies an array of requirements for matching namespaces. If a match is found, then routes from the matching namespace(s) are allowed to attach to the `Gateway`. The following table describes members of the `matchExpressions` array:

| Requirement |                                                                                                                       Description                                                                                                                      |       Type       |
|:-----------:|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------:|:----------------:|
| key         | Specifies that label that the key applies to.                                                                                                                                                                                                          | string           |
| operator    | Specifies the key's relation to a set of values. The following values are valid:In: description of what this means NotIn: description of what this means Exists: description of what this means DoesNotExist: description of what this means           | string           |
| values      | Specifies an array of string values. If the operator is configured to In or NotIn,the values array must be non-empty. If theoperator is Exists or DoesNotExist, the values array must be empty. This array is replaced during a strategic merge patch. | array of strings |
| scope       | Specifies the effective scope of the Gateway. The value should always be namespaced.                                                                                                                                                                   | Required         |
| fields      | Specifies the configurations for the Gateway. The fields are listed in the Configuration model. Details for each field are described in the Specification.                                                                                             | Required         |

```yaml
namespaceSelector:
  matchExpressions:
  - key: kubernetes.io/metadata.name
    operator: In
    values:
    - foo
    - bar
```

### listeners.allowedRoutes.namespaces.selector.matchLabels
Specifies an array of labels and label values. If a match is found, then routes with the matching label(s) are allowed to attach to the `Gateway`. This selector can contain any arbitrary key/value pair.

```yaml
namespaceSelector:
    matchLabels:
      foo: bar
```

For more on labels, see [Labels and Selectors](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/)

### listeners.hostname
Specifies the `listeners` hostname
* Type: string
* Required: required

### listeners.name
Specifies the `listener`'s name
* Type: string
* Required: required

### listeners.port
Specifies the port number that the `listener` will attach to
* Type: integer
* Required: required

### listeners.protocol
Specifies the protocol the `listener` will use
* Type: string
* Required: required

Allowed values are `TCP`, `HTTP`, or `HTTPS`

### listeners.tls
* Type: Object
* Required: required if `protocol` is set to `HTTPS`

### listeners.tls.certificateRefs
`CertificateRefs` contains a series of references to Kubernetes objects that contains TLS certificates and private keys. These certificates are used to establish a TLS handshake for requests that match the hostname of the associated `listener`. Each reference must be a Kubernetes Secret, and, if using a Secret in a namespace other than the`Gateway`'s, must have a corresponding `ReferencePolicy` created.
* Type: Object or Array
* Required: required if `tls` is set

### listeners.tls.mode
* Type: String
* Required: required if certificateRefs is set

### listeners.tls.options
* Type: Map of Strings
* Required: optional

## Complete configuration
The following example shows a fully configured `Gateway`.

```yaml
kind: Gateway
Description: This gateway enables traffic from A to B.
version: gateway.networking.k8s.io/v1alpha2
scope: Namespaced
fields:
  - name: addresses
    supported: false
  - name: gatewayClassName
    type: string
    description: Name of a GatewayClass resource used for this Gateway.
  - name: listeners
    type: array<object>
    description: |
      Description of the listeners associated with this Gateway.
    items:
      fields:
        - name: allowedRoutes
          type: object
          description: |
            AllowedRoutes defines the types of routes that
            MAY be attached to a Listener and the trusted namespaces where
            those Route resources MAY be present.
          fields:
            - name: kinds
              supported: false
            - name: namespaces
              type: object
              description: |
                Description of namespaces from which routes may be attached to this Listener. This is restricted
                to the namespace of this Gateway by default.
              fields:
                - name: from
                  type: string
                  default: Same
                  description: |
                    From indicates where Routes will be selected
                    for this Gateway."
                  enum: ["All", "Selector", "Same"]
                - name: selector
                  type: object
                  description: "Selector must be specified when From is
                    set to \"Selector\". In that case, only Routes in
                    Namespaces matching this Selector will be selected
                    by this Gateway."
                  fields:
                    - name: matchExpressions
                      type: array<object>
                      description: |
                        matchExpressions is a list of label
                        selector requirements. The requirements are ANDed.
                      items:
                        fields:
                          - name: key
                            type: string
                            description: |
                              key is the label key that the
                              selector applies to.
                          - name: operator
                            type: string
                            description: |
                              operator represents a key's relationship
                              to a set of values. Valid operators are
                              In, NotIn, Exists and DoesNotExist.
                          - name: values
                            type: array<string>
                            description: |
                              values is an array of string
                              values. If the operator is In or NotIn,
                              the values array must be non-empty. If the
                              operator is Exists or DoesNotExist, the
                              values array must be empty. This array is
                              replaced during a strategic merge patch.
                    - name: matchLabels
                      type: map<string, string>
                      description: |
                        matchLabels is a map of {key,value}
                        pairs. A single {key,value} in the matchLabels
                        map is equivalent to an element of matchExpressions,
                        whose key field is "key", the operator is "In",
                        and the values array contains only "value". The
                        requirements are ANDed.
        - name: hostname
          type: string
          description: |
            Hostname specifies the virtual hostname to match for HTTP or HTTPS-based listeners. When unspecified,
            all hostnames are matched. This is implemented by checking the HTTP Host header sent on a client request.
        - name: name
          type: string
          description: "Name is the name of the Listener. This name MUST be unique within a Gateway."
        - name: port
          type: integer
          description: "Port is the network port of a listener."
        - name: protocol
          type: string
          description: "Protocol specifies the network protocol this listener expects to receive."
          enum: ["HTTP", "HTTPS", "TCP"]
        - name: tls
          type: object
          description: |
            TLS is the TLS configuration for the Listener.
            This field is required if the Protocol field is "HTTPS".
            It is invalid to set this field if the Protocol
            field is "HTTP" or "TCP".
          fields:
            - name: certificateRefs
              type: array<object>
              description: |
                CertificateRefs contains a series of references
                to Kubernetes objects that contains TLS certificates and
                private keys. These certificates are used to establish
                a TLS handshake for requests that match the hostname of
                the associated listener. Each reference must be a Kubernetes
                Secret, and, if using a Secret in a namespace other than the
                Gateway's, must have a corresponding ReferencePolicy created.
              items:
                fields:
                  - name: group
                    supported: false
                  - name: kind
                    supported: false
                  - name: name
                    type: string
                    description: Name is the name of the Kubernetes Secret.
                  - name: namespace
                    type: string
                    description: |
                      Namespace is the namespace of the Secret. When unspecified, the local namespace is inferred.

                      Note that when a namespace is specified, a ReferencePolicy
                      object is required in the specified namespace to
                      allow that namespace's owner to accept the reference.
            - name: mode
              type: string
              default: Terminate
              description: "Mode defines the TLS behavior for the TLS session initiated by the client. The only supported mode at this time is `Terminate`"
              enum: ["Terminate"]
            - name: options
              type: map<string, string>
              description: |
                Options are a list of key/value pairs to enable
                extended TLS configuration for each implementation.
              enum: ["api-gateway.consul.hashicorp.com/tls_min_version","api-gateway.consul.hashicorp.com/tls_max_version","api-gateway.consul.hashicorp.com/tls_cipher_suites",]
```