--- layout: docs page_title: External <> Internal Services - Ingress Gateways 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. --- # Ingress Gateways -> **1.8.0+:** This feature is available in Consul versions 1.8.0 and newer. Ingress gateways enable ingress traffic from services outside the Consul service mesh to services inside the Consul service mesh. An ingress gateway is a type of proxy and must be registered as a service in Consul, with the [kind](/api/agent/service#kind) set to "ingress-gateway". They are an entrypoint for outside traffic and allow you to define what services should be exposed and on what port. You configure an ingress gateway by defining a set of [listeners](/docs/connect/config-entries/ingress-gateway#listeners) that each map to a set of backing [services](/docs/connect/config-entries/ingress-gateway#services). To enable easier service discovery, a new Consul [DNS subdomain](/docs/discovery/dns#ingress-service-lookups) is provided, on `.ingress.`. For listeners with a [protocol](/docs/connect/config-entries/ingress-gateway#protocol) other than `tcp`, multiple services can be specified for a single listener. In this case, the ingress gateway relies on host/authority headers to decide the service that should receive the traffic. The host used to match traffic defaults to the [Consul DNS ingress subdomain](/docs/discovery/dns#ingress-service-lookups), but can be changed using the [hosts](/docs/connect/config-entries/ingress-gateway#hosts) field. ![Ingress Gateway Architecture](/img/ingress-gateways.png) ## Prerequisites Ingress gateways also require that your Consul datacenters are configured correctly: - You'll need to use Consul version 1.8.0 or newer. - Consul [Connect](/docs/agent/options#connect) must be enabled on the datacenter's Consul servers. - [gRPC](/docs/agent/options#grpc_port) must be enabled on all client agents. Currently, [Envoy](https://www.envoyproxy.io/) is the only proxy with ingress gateway capabilities in Consul. ## Running and Using an Ingress Gateway For a complete example of how to allow external traffic inside your Consul service mesh, review the [ingress gateway tutorial](https://learn.hashicorp.com/tutorials/consul/service-mesh-ingress-gateways). ## Ingress Gateway Configuration Ingress gateways are configured in service definitions and registered with Consul like other services, with two exceptions. The first is that the [kind](/api/agent/service#kind) must be "ingress-gateway". Second, the ingress 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, ingress gateways must be registered with a token granting `service:write` for the ingress gateway's service name, `service:read` for all services in the ingress gateway's configuration entry, and `node:read` for all nodes of the services in the ingress gateway's configuration entry. These privileges authorize the token to route communications to other Connect services. If the Consul client agent on the gateway's node is not configured to use the default gRPC port, 8502, then the gateway's token must also provide `agent:read` for its node's name in order to discover the agent's gRPC port. gRPC is used to expose Envoy's xDS API to Envoy proxies. ~> [Configuration entries](/docs/agent/config-entries) are global in scope. A configuration entry for a gateway name applies across all federated Consul datacenters. If ingress gateways in different Consul datacenters need to route to different sets of services within their datacenter, then the ingress gateways **must** be registered with different names. ## Custom TLS Certificates via Secret Discovery Service (SDS) ~> **Advanced Topic** This is a low-level feature designed for developers building integrations with custom TLS management solutions. Consul 1.11 added support for Ingress Gateways to serve TLS certificates to inbound traffic that are sourced from an external service. The external service must implement Envoy's [gRPC Secret Discovery Service](https://www.envoyproxy.io/docs/envoy/latest/configuration/security/secret) (or SDS) API. The following procedure describes how to configure an ingress gateway with TLS certificates from an SDS source. The instructions assume that you are familiar with Envoy configuration and the SDS protocol. ### 1. Configure Static SDS Cluster(s) Each Envoy proxy that makes up this Ingress Gateway must define one or more additional [static clusters](/docs/connect/proxies/envoy#envoy_extra_static_clusters_json) when registering. These additional clusters define how Envoy should connect to the required SDS service(s). Defining extra clusters in Envoy's bootstrap configuration requires a manual registration of the Ingress Gateway with Consul proxy. It's not possible to use the `-register` flag with `consul connect envoy -gateway=ingress` to automatically register the proxy in this case. The cluster(s) must provide connection information and any necessary authentication information such as mTLS credentials. In this example we will show: - A DNS name to discover the SDS service addresses - Local certificate files for TLS client authentication with the SDS server (the certificates are assumed to be created and managed by some other process) #### 1.1 Registering the Proxy Service The following Proxy Service Definition defines the bootstrap overrides needed to add this configuration to Envoy when it starts. With this TLS configuration, Envoy will detect changes to the certificate and key files on disk so an external process may maintain and rotate them without needing an Envoy restart. ```hcl // public-ingress.hcl Services { Name = "public-ingress" Kind = "ingress-gateway" Proxy { Config { envoy_extra_static_clusters_json = <