mirror of https://github.com/hashicorp/consul
170 lines
5.0 KiB
Markdown
170 lines
5.0 KiB
Markdown
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---
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layout: "docs"
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page_title: "Connect - Mesh Gateways (beta)"
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sidebar_current: "docs-connect-meshgateways"
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description: |-
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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.
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---
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# Mesh Gateways <sup>(beta)</sup>
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Mesh gateways enable routing of Connect traffic between different Consul datacenters. Those datacenters
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can reside in different clouds or runtime environments where general interconnectivity between all services
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in all datacenters isn't feasible. These gateways operate by sniffing the SNI header out of the Connect session
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and then route the connection to the appropriate destination based on the server name requested. The data
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within the Connect session is not decrypted by the Gateway.
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![Mesh Gateway Architecture](/assets/images/mesh-gateways.png)
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## Prerequisites
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Each mesh gateway needs three things:
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1. A local Consul agent to manage its configuration.
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2. General network connectivity to all services within its local Consul datacenter.
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3. General network connectivity to all mesh gateways within remote Consul datacenters.
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## Modes of Operation
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Each upstream of a Connect proxy can be configured to be routed through a mesh gateway. Depending on
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your network, the proxy's connection to the gateway can happen in one of the following modes:
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* `local` - In this mode the Connect proxy makes its outbound connection to a gateway running in the
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same datacenter. That gateway is then responsible for ensuring the data gets forwarded along to
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gateways in the destination datacenter. This is the mode of operation depicted in the diagram at
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the beginning of the page.
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* `remote` - In this mode the Connect proxy makes its outbound connection to a gateway running in the
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destination datacenter. That gateway will then forward the data to the final destination service.
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* `none` - In this mode, no gateway is used and a Connect proxy makes its outbound connections directly
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to the destination services.
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## Mesh Gateway Configuration
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Mesh gateways are defined very similarly to other typical services. The one exception is that a mesh gateway
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service definition may contain a `Proxy.Config` entry just like a Connect proxy service to define opaque
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configuration parameters useful for the actual proxy software.
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## Connect Proxy Configuration
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Configuring a Connect Proxy to use gateways is as simple as setting its mode of operation. This can be done
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in several different places allowing for global to more fine grained control. If the gateway mode is configured
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in multiple locations the order of precedence is as follows
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1. Upstream Definition
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2. Service Instance Definition
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3. Centralized `service-defaults` configuration entry
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4. Centralized `proxy-defaults` configuration entry.
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### Enabling Gateways Globally
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The following `proxy-defaults` configuration will enable gateways for all Connect services in the `local` mode.
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```hcl
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Kind = "proxy-defaults"
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Name = "global"
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MeshGateway {
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Mode = "local"
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}
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```
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### Enabling Gateways Per-Service
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The following `service-defaults` configuration will enable gateways for all Connect services with the name "web".
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```hcl
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Kind = "service-defaults"
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Name = "web"
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MeshGateway {
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Mode = "local"
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}
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```
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### Enabling Gateways for a Service Instance
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The following service definition will enable gateways for the service instance in the `remote` mode.
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```hcl
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service {
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name = "web-sidecar-proxy"
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port = 8181
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proxy {
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destination_service_name = "web"
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mesh_gateway {
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mode = "remote"
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}
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upstreams = [
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{
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destination_name = "api"
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datacenter = "secondary"
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local_bind_port = 10000
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}
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]
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}
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}
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```
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Or alternatively as a sidecar service:
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```hcl
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service {
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name = "web"
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port = 8181
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connect {
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sidecar_service {
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proxy {
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mesh_gateway {
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mode = "remote"
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}
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upstreams = [
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{
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destination_name = "api"
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datacenter = "secondary"
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local_bind_port = 10000
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}
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]
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}
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}
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}
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}
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```
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### Enabling Gateways for a Proxy Upstream
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The following service definition will enable gateways in the `local` mode for one upstream, the `remote` mode
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for a second upstream and will disable gateways for a third upstream.
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```hcl
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service {
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name = "web-sidecar-proxy"
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port = 8181
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proxy {
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destination_service_name = "web"
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upstreams = [
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{
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destination_name = "api"
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local_bind_port = 10000
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mesh_gateway {
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mode = "remote"
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}
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},
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{
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destination_name = "db"
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local_bind_port = 10001
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mesh_gateway {
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mode = "local"
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}
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},
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{
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destination_name = "logging"
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local_bind_port = 10002
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mesh_gateway {
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mode = "none"
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}
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},
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]
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}
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}
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```
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