clarify mesh gateway docs use cases; include admin partition flow

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trujillo-adam 2021-12-15 13:11:52 -08:00
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# Gateways
Gateways provide connectivity into, out of, and between Consul service meshes.
This topic provides an overview of the gateway features shipped with Consul. Gateways provide connectivity into, out of, and between Consul service meshes. You can configure the following types of gateways:
- Enable service-to-service traffic between Consul datacenters with [mesh gateways](#mesh-gateways).
- Accept traffic from outside the Consul service mesh to services in the mesh with [ingress gateways](#ingress-gateways).
- Route traffic from services in the Consul service mesh to external services with [terminating gateways](#terminating-gateways).
- [Mesh gateways](#mesh-gateways) enable service-to-service traffic between Consul datacenters or between Consul admin partitions. They also enable datacenters to be federated across wide area networks.
- [Ingress gateways](#ingress-gateways) enable services to accept traffic from outside the Consul service mesh.
- [Terminating gateways](#terminating-gateways) enable you to route traffic from services in the Consul service mesh to external services.
## Mesh Gateways
-> **1.6.0+:** This feature is available in Consul versions 1.6.0 and newer.
Mesh gateways enable routing of service mesh traffic between different Consul datacenters. Those datacenters can reside
Mesh gateways enable service mesh traffic to be routed between different Consul datacenters and admin partitions. The datacenters or partitions can reside
in different clouds or runtime environments where general interconnectivity between all services in all datacenters
isn't feasible. One scenario where this is useful is when connecting networks with overlapping IP address space.
isn't feasible.
These gateways operate by sniffing the SNI header out of the mTLS connection and then routing the connection to the
appropriate destination based on the server name requested. The data within the mTLS session is not decrypted by
the Gateway.
They operate by sniffing and extracting the server name indication (SNI) header from the service mesh session and routing the connection to the appropriate destination based on the server name requested. The gateway does not decrypt the data within the mTLS session.
As of Consul 1.8.0, mesh gateways can also forward gossip and RPC traffic between Consul servers.
This is enabled by [WAN federation via mesh gateways](/docs/connect/gateways/wan-federation-via-mesh-gateways).
Mesh gateways enable the following scenarios:
For more information about mesh gateways, review the [complete documentation](/docs/connect/gateways/mesh-gateway)
and the [mesh gateway tutorial](https://learn.hashicorp.com/tutorials/consul/service-mesh-gateways).
* **Federate multiple datacenters across a WAN**. Since Consul 1.8.0, mesh gateways can forward gossip and RPC traffic between Consul servers. See [WAN federation via mesh gateways](/docs/connect/gateways/wan-federation-via-mesh-gateways) for additional information.
* **Service-to-service communication across datacenters**. Refer to [Enabling Service-to-service Traffic Accross Datacenters](/docs/connect/gateways/mesh-gateway/service-to-service-traffic-datacenters) for additional information.
* **Service-to-service communication across admin partitions**. Since Consul 1.11.0, you can create administrative boundaries for single Consul deployements called "admin partitions". You can use mesh gateways to facilitate cross-partition communication. Refer to [Enabling Service-to-service Traffic Accross Admin Partitions](/docs/connect/gateways/mesh-gateway/service-to-service-traffic-partitions) for additional information.
![Mesh Gateway Architecture](/img/mesh-gateways.png)
-> **Mesh gateway tutorial**: Follow the [mesh gateway tutorial](https://learn.hashicorp.com/tutorials/consul/service-mesh-gateways) to learn concepts associated with mesh gateways.
## Ingress Gateways

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---
layout: docs
page_title: External <> Internal Services - Ingress Gateways
page_title: Using Ingress Gateways to Connect External Traffic to Internal Services
description: >-
An ingress gateway enables ingress traffic from services outside the Consul
service mesh to services inside the Consul service mesh. This section details
how to use Envoy and describes how you can plug in a gateway of your choice.
This topic describes how ingress gateways enable traffic from external services to reach services inside the Consul service mesh.
It provides guidance on how to use Envoy and how to plug into your preferred gateway.
---
# Ingress Gateways

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---
layout: docs
page_title: Connect Datacenters - Mesh Gateways
description: >-
A Mesh Gateway enables better routing of a Connect service's data to upstreams
in other datacenters. This section details how to use Envoy and describes how
you can plug in a gateway of your choice.
---
# Mesh Gateways
-> **1.6.0+:** This feature is available in Consul versions 1.6.0 and newer.
Mesh gateways enable routing of Connect traffic between different Consul datacenters. Those datacenters
can reside in different clouds or runtime environments where general interconnectivity between all services
in all datacenters isn't feasible. These gateways operate by sniffing the SNI header out of the Connect session
and then route the connection to the appropriate destination based on the server name requested. The data
within the mTLS session is not decrypted by the Gateway.
![Mesh Gateway Architecture](/img/mesh-gateways.png)
For a complete example of how to connect services across datacenters,
review the [mesh gateway tutorial](https://learn.hashicorp.com/tutorials/consul/service-mesh-gateways).
## Prerequisites
Each mesh gateway needs three things:
1. A local Consul agent to manage its configuration.
2. General network connectivity to all services within its local Consul datacenter.
3. General network connectivity to all mesh gateways within remote Consul datacenters.
Mesh gateways also require that your Consul datacenters are configured correctly:
- Consul version 1.6.0 or newer is required.
- Consul [Connect](/docs/agent/options#connect) must be enabled in both datacenters.
- Each of your [datacenters](/docs/agent/options#datacenter) must have a unique name.
- Your datacenters must be [WAN joined](https://learn.hashicorp.com/tutorials/consul/federarion-gossip-wan).
- The [primary datacenter](/docs/agent/options#primary_datacenter) must be set to the same value in both datacenters. This specifies which datacenter is the authority for Connect certificates and is required for services in all datacenters to establish mutual TLS with each other.
- [gRPC](/docs/agent/options#grpc_port) must be enabled.
- If you want to [enable gateways globally](/docs/connect/mesh-gateway#enabling-gateways-globally) you must enable [centralized configuration](/docs/agent/options#enable_central_service_config).
Currently, Envoy is the only proxy with mesh gateway capabilities in Consul.
- Mesh gateway proxies receive their configuration through Consul, which
automatically generates it based on the proxy's registration. Currently Consul
can only translate mesh gateway registration information into Envoy
configuration, therefore the proxies acting as mesh gateways must be Envoy.
- Sidecar proxies that send traffic to an upstream service through a gateway
need to know the location of that gateway. They discover the gateway based on
their sidecar proxy registrations. Consul can only translate the gateway
registration information into Envoy configuration, so any sidecars that send
upstream traffic through a gateway must be Envoy.
Sidecar proxies that don't send upstream traffic through a gateway aren't
affected when you deploy gateways. If you are using Consul's built-in proxy as a
Connect sidecar it will continue to work for intra-datacenter traffic and will
receive incoming traffic even if that traffic has passed through a gateway.
## Modes of Operation
Each upstream of a Connect proxy can be configured to be routed through a mesh gateway. Depending on
your network, the proxy's connection to the gateway can happen in one of the following modes
illustrated in the diagram above:
- `local` - In this mode the Connect proxy makes its outbound connection to a gateway running in the
same datacenter. That gateway is then responsible for ensuring the data gets forwarded along to
gateways in the destination datacenter. This is the mode of operation depicted in the diagram at
the beginning of the page.
- `remote` - In this mode the Connect proxy makes its outbound connection to a gateway running in the
destination datacenter. That gateway will then forward the data to the final destination service.
- `none` - In this mode, no gateway is used and a Connect proxy makes its outbound connections directly
to the destination services.
## Mesh Gateway Configuration
Mesh gateways are defined similarly to other services registered with Consul, with two exceptions.
The first is that the [service kind](/api/agent/service#kind) must be "mesh-gateway". Second,
the mesh gateway service definition may contain a `Proxy.Config` entry, just like a
Connect proxy service, to define opaque configuration parameters useful for the actual proxy software.
For Envoy there are some supported [gateway options](/docs/connect/proxies/envoy#gateway-options) as well as
[escape-hatch overrides](/docs/connect/proxies/envoy#escape-hatch-overrides).
-> **Note:** If ACLs are enabled, a token granting `service:write` for the gateway's service name
and `service:read` for all services in the datacenter must be added to the gateway's service definition.
These permissions authorize the token to route communications for other Connect services but does not
allow decrypting any of their communications.
## Connect Proxy Configuration
Configuring a Connect Proxy to use gateways is as simple as setting its mode of operation. This can be done
in several different places allowing for global to more fine grained control. If the gateway mode is configured
in multiple locations the order of precedence is as follows
1. Upstream Definition
2. Service Instance Definition
3. Centralized `service-defaults` configuration entry
4. Centralized `proxy-defaults` configuration entry.
### Enabling Gateways Globally
The following `proxy-defaults` configuration will enable gateways for all Connect services in the `local` mode.
```hcl
Kind = "proxy-defaults"
Name = "global"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways Per-Service
The following `service-defaults` configuration will enable gateways for all Connect services with the name "web".
```hcl
Kind = "service-defaults"
Name = "web"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways for a Service Instance
The following [Proxy Service Registration](/docs/connect/registration/service-registration)
definition will enable gateways for the service instance in the `remote` mode.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
mesh_gateway {
mode = "remote"
}
upstreams = [
{
destination_name = "api"
datacenter = "secondary"
local_bind_port = 10000
}
]
}
}
```
Or alternatively inline with the service definition:
```hcl
service {
name = "web"
port = 8181
connect {
sidecar_service {
proxy {
mesh_gateway {
mode = "remote"
}
upstreams = [
{
destination_name = "api"
datacenter = "secondary"
local_bind_port = 10000
}
]
}
}
}
}
```
### Enabling Gateways for a Proxy Upstream
The following service definition will enable gateways in the `local` mode for one upstream, the `remote` mode
for a second upstream and will disable gateways for a third upstream.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
upstreams = [
{
destination_name = "api"
local_bind_port = 10000
mesh_gateway {
mode = "remote"
}
},
{
destination_name = "db"
local_bind_port = 10001
mesh_gateway {
mode = "local"
}
},
{
destination_name = "logging"
local_bind_port = 10002
mesh_gateway {
mode = "none"
}
},
]
}
}
```

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---
layout: docs
page_title: Service-to-service Traffic Across Datacenters
description: >-
This topic describes how to configure mesh gateways to route a service's data to upstreams
in other datacenters. It describes how to use Envoy and how you can integrate with your preferred gateway.
---
# Service-to-service Traffic Across Datacenters
-> **1.6.0+:** This feature is available in Consul versions 1.6.0 and newer.
Mesh gateways enable service mesh traffic to be routed between different Consul datacenters.
Datacenters can reside in different clouds or runtime environments where general interconnectivity between all services
in all datacenters isn't feasible.
Mesh gateways operate by sniffing and extracting the server name indication (SNI) header from the service mesh session and routing the connection to the appropriate destination based on the server name requested. The gateway does not decrypt the data within the mTLS session.
The following diagram describes the architecture for using mesh gateways for cross-datacenter communication:<a name="mesh-architecture-diagram"/>
![Mesh Gateway Architecture](/img/mesh-gateways.png)
-> **Mesh Gateway Tutorial**: Follow the [mesh gateway tutorial](https://learn.hashicorp.com/tutorials/consul/service-mesh-gateways) to learn important concepts associated with using mesh gateways for connecting services across datacenters.
## Prerequisites
Ensure that your Consul environment meets the following requirements.
### Consul
* Consul version 1.6.0 or newer.
* A local Consul agent is required to manage its configuration.
* Consul [Connect](/docs/agent/options#connect) must be enabled in both datacenters.
* Each [datacenter](/docs/agent/options#datacenter) must have a unique name.
* Each datacenters must be [WAN joined](https://learn.hashicorp.com/tutorials/consul/federarion-gossip-wan).
* The [primary datacenter](/docs/agent/options#primary_datacenter) must be set to the same value in both datacenters. This specifies which datacenter is the authority for Connect certificates and is required for services in all datacenters to establish mutual TLS with each other.
* [gRPC](/docs/agent/options#grpc_port) must be enabled.
* If you want to [enable gateways globally](/docs/connect/mesh-gateway#enabling-gateways-globally) you must enable [centralized configuration](/docs/agent/options#enable_central_service_config).
### Network
* General network connectivity to all services within its local Consul datacenter.
* General network connectivity to all mesh gateways within remote Consul datacenters.
### Proxy
Envoy is the only proxy with mesh gateway capabilities in Consul.
Mesh gateway proxies receive their configuration through Consul, which automatically generates it based on the proxy's registration.
Consul can only translate mesh gateway registration information into Envoy configuration.
Sidecar proxies that send traffic to an upstream service through a gateway need to know the location of that gateway. They discover the gateway based on their sidecar proxy registrations. Consul can only translate the gateway registration information into Envoy configuration.
Sidecar proxies that do not send upstream traffic through a gateway are not affected when you deploy gateways. If you are using Consul's built-in proxy as a Connect sidecar it will continue to work for intra-datacenter traffic and will receive incoming traffic even if that traffic has passed through a gateway.
## Configuration
Configure the following settings to register the mesh gateway as a service in Consul.
* Specify `mesh-gateway` in the `kind` field to register the gateway with Consul.
* Define the `Proxy.Config` settings using opaque parameters compatible with your proxy, i.e., Envoy. For Envoy, refer to the [Gateway Options](/docs/connect/proxies/envoy#gateway-options) and [Escape-hatch Overrides](/docs/connect/proxies/envoy#escape-hatch-overrides) documentation for additional configuration information.
* If ACLs are enabled, a token granting `service:write` for the gateway's service name and `service:read` for all services in the datacenter or partition must be added to the gateway's service definition. These permissions authorize the token to route communications for other Consul service mesh services, but does not allow decrypting any of their communications.
### Modes
Each upstream associated with a service mesh proxy can be configured so that it is routed through a mesh gateway.
Depending on your network, the proxy's connection to the gateway can operate in one of the following modes (refer to the [mesh-architecture-diagram](#mesh-architecture-diagram)):
* `none` - (Default) No gateway is used and a service mesh connect proxy makes its outbound connections directly
to the destination services.
* `local` - The service mesh connect proxy makes an outbound connection to a gateway running in the
same datacenter. That gateway is responsible for ensuring that the data is forwarded to gateways in the destination datacenter.
Refer to the flow labeled `local` in the [mesh-architecture-diagram](#mesh-architecture-diagram).
* `remote` - The service mesh proxy makes an outbound connection to a gateway running in the destination datacenter.
The gateway forwards the data to the final destination service.
Refer to the flow labeled `remote` in the [mesh-architecture-diagram](#mesh-architecture-diagram).
### Connect Proxy Configuration
Set the proxy to the preferred [mode](#modes) to configure the service mesh proxy. You can specify the mode globally or within child configurations to control proxy behaviors at a lower level. Consul recognizes the following order of precedence if the gateway mode is configured in multiple locations the order of precedence:
1. Upstream definition (highest priority)
2. Service instance definition
3. Centralized `service-defaults` configuration entry
4. Centralized `proxy-defaults` configuration entry
## Example Configurations
Use the following example configurations to help you understand some of the common scenarios.
### Enabling Gateways Globally
The following `proxy-defaults` configuration will enable gateways for all Connect services in the `local` mode.
```hcl
Kind = "proxy-defaults"
Name = "global"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways Per-Service
The following `service-defaults` configuration will enable gateways for all Connect services with the name "web".
```hcl
Kind = "service-defaults"
Name = "web"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways for a Service Instance
The following [Proxy Service Registration](/docs/connect/registration/service-registration)
definition will enable gateways for the service instance in the `remote` mode.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
mesh_gateway {
mode = "remote"
}
upstreams = [
{
destination_name = "api"
datacenter = "secondary"
local_bind_port = 10000
}
]
}
}
```
Or alternatively inline with the service definition:
```hcl
service {
name = "web"
port = 8181
connect {
sidecar_service {
proxy {
mesh_gateway {
mode = "remote"
}
upstreams = [
{
destination_name = "api"
datacenter = "secondary"
local_bind_port = 10000
}
]
}
}
}
}
```
### Enabling Gateways for a Proxy Upstream
The following service definition will enable gateways in the `local` mode for one upstream, the `remote` mode
for a second upstream and will disable gateways for a third upstream.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
upstreams = [
{
destination_name = "api"
local_bind_port = 10000
mesh_gateway {
mode = "remote"
}
},
{
destination_name = "db"
local_bind_port = 10001
mesh_gateway {
mode = "local"
}
},
{
destination_name = "logging"
local_bind_port = 10002
mesh_gateway {
mode = "none"
}
},
]
}
}
```

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---
layout: docs
page_title: Service-to-service Traffic Across Partitions
description: >-
This topic describes how to configure mesh gateways to route a service's data to upstreams
in other partitions. It describes how to use Envoy and how you can integrate with your preferred gateway.
---
# Service-to-service Traffic Across Partitions
-> **Consul Enterprise 1.11.0+:** Admin partitions are supported in Consul Enterprise versions 1.11.0 and newer.
Mesh gateways enable you to route service mesh traffic between different Consul [admin partitions](/docs/enteprise/admin-partitions).
Partitions can reside in different clouds or runtime environments where general interconnectivity between all services
in all partitions isn't feasible.
Mesh gateways operate by sniffing and extracting the server name indication (SNI) header from the service mesh session and routing the connection to the appropriate destination based on the server name requested. The gateway does not decrypt the data within the mTLS session.
## Prerequisites
Ensure that your Consul environment meets the following requirements.
### Consul
* Consul Enterprise version 1.11.0 or newer.
* A local Consul agent is required to manage its configuration.
* Consul service mesh must be enabled in all partitions. Refer to the [`connect` documentation](/docs/agent/options#connect) for details.
* Each partition must have a unique name. Refer to the [admin partitions documentation](/docs/enteprise/admin-partitions) for details.
* If you want to [enable gateways globally](/docs/connect/mesh-gateway#enabling-gateways-globally) you must enable [centralized configuration](/docs/agent/options#enable_central_service_config).
### Proxy
Envoy is the only proxy with mesh gateway capabilities in Consul.
Mesh gateway proxies receive their configuration through Consul, which automatically generates it based on the proxy's registration.
Consul can only translate mesh gateway registration information into Envoy configuration.
Sidecar proxies that send traffic to an upstream service through a gateway need to know the location of that gateway. They discover the gateway based on their sidecar proxy registrations. Consul can only translate the gateway registration information into Envoy configuration.
Sidecar proxies that do not send upstream traffic through a gateway are not affected when you deploy gateways. If you are using Consul's built-in proxy as a Connect sidecar it will continue to work for intra-datacenter traffic and will receive incoming traffic even if that traffic has passed through a gateway.
## Configuration
Configure the following settings to register the mesh gateway as a service in Consul.
* Specify `mesh-gateway` in the `kind` field to register the gateway with Consul.
* Define the `Proxy.Config` settings using opaque parameters compatible with your proxy, i.e., Envoy. For Envoy, refer to the [Gateway Options](/docs/connect/proxies/envoy#gateway-options) and [Escape-hatch Overrides](/docs/connect/proxies/envoy#escape-hatch-overrides) documentation for additional configuration information.
* Configure the `proxy.upstreams` parameters to route traffic to the correct service, namespace, and partition. Refer to the [`upstreams` documentation](/docs/connect/registration/service-registration#upstream-configuration-reference) for details.
* Configure the `exported-services` configuration entry to enable Consul to export services contained in an admin partition to one or more additional partitions. Refer to the [Exported Services documentation](/docs/connect/config-entries/exported-services) for details.
* If ACLs are enabled, a token granting `service:write` for the gateway's service name and `service:read` for all services in the datacenter or partition must be added to the gateway's service definition. These permissions authorize the token to route communications for other Consul service mesh services, but does not allow decrypting any of their communications.
### Modes
Each upstream associated with a service mesh proxy can be configured so that it is routed through a mesh gateway.
Depending on your network, the proxy's connection to the gateway can operate in one of the following modes:
* `none` - (Default) No gateway is used and a service mesh connect proxy makes its outbound connections directly
to the destination services.
* `local` - The service mesh connect proxy makes an outbound connection to a gateway running in the same datacenter. The gateway at the outbound connection is responsible for ensuring that the data is forwarded to gateways in the destination partition.
* `remote` - The service mesh connect proxy makes an outbound connection to a gateway running in the destination datacenter.
The gateway forwards the data to the final destination service.
### Connect Proxy Configuration
Set the proxy to the preferred [mode](#modes) to configure the service mesh proxy. You can specify the mode globally or within child configurations to control proxy behaviors at a lower level. Consul recognizes the following order of precedence if the gateway mode is configured in multiple locations the order of precedence:
1. Upstream definition (highest priority)
2. Service instance definition
3. Centralized `service-defaults` configuration entry
4. Centralized `proxy-defaults` configuration entry
## Example Configurations
Use the following example configurations to help you understand some of the common scenarios.
### Enabling Gateways Globally
The following `proxy-defaults` configuration will enable gateways for all Connect services in the `local` mode.
```hcl
Kind = "proxy-defaults"
Name = "global"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways Per-Service
The following `service-defaults` configuration will enable gateways for all Connect services with the name `web`.
```hcl
Kind = "service-defaults"
Name = "web"
MeshGateway {
Mode = "local"
}
```
### Enabling Gateways for a Service Instance
The following [Proxy Service Registration](/docs/connect/registration/service-registration)
definition will enable gateways for `web` service instances in the `finance` partition.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
mesh_gateway {
mode = "local"
}
upstreams = [
{
destination_partition = "finance"
destination_namespace = "default"
destination_type = "service"
destination_name = "billing"
local_bind_port = 9090
}
]
}
}
```
### Enabling Gateways for a Proxy Upstream
The following service definition will enable gateways in `local` mode for three different partitions. Note that each service exists in the same namepace, but are separated by admin partition.
```hcl
service {
name = "web-sidecar-proxy"
kind = "connect-proxy"
port = 8181
proxy {
destination_service_name = "web"
upstreams = [
{
destination_name = "api"
destination_namespace = "dev"
destination_partition = "api"
local_bind_port = 10000
mesh_gateway {
mode = "local"
}
},
{
destination_name = "db"
destination_namespace = "dev"
destination_partition = "db"
local_bind_port = 10001
mesh_gateway {
mode = "local"
}
},
{
destination_name = "logging"
destination_namespace = "dev"
destination_partition = "logging"
local_bind_port = 10002
mesh_gateway {
mode = "local"
}
},
]
}
}
```

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@ -277,24 +277,28 @@
"path": "connect/gateways"
},
{
"title": "Connect Datacenters - Mesh Gateways",
"title": "Mesh Gateways",
"routes": [
{
"title": "Overview",
"path": "connect/gateways/mesh-gateway"
},
{
"title": "WAN Federation",
"path": "connect/gateways/mesh-gateway/wan-federation-via-mesh-gateways"
},
{
"title": "Enabling Service-to-service Traffic Across Datacenters",
"path": "connect/gateways/mesh-gateway/service-to-service-traffic-datacenters"
},
{
"title": "Enabling Service-to-service Traffic Across Admin Partitions",
"path": "connect/gateways/mesh-gateway/service-to-service-traffic-partitions"
}
]
},
{
"title": "External <> Internal Services - Ingress Gateways",
"title": "Ingress Gateways",
"path": "connect/gateways/ingress-gateway"
},
{
"title": "Internal <> External Services - Terminating Gateways",
"title": "Terminating Gateways",
"path": "connect/gateways/terminating-gateway"
}
]