xds

xds

Provide building blocks to bootstrap a xDS server to be used as control plane for managing gRPC Microservices.
It can run in Kubernetes as well as local development environment, making it easy to use both in production and during development.

Features

• Universal Control Plane: Easy to use, distributed, runs anywhere on both Kubernetes and local development.
• Lightweight: stateless, scale up/down
• Traffic Routing: With dynamic load-balancing for blue/green, canary, versioning and rollback deployments.
• Metrics: export prometheus complaint metrics via OpenTelemetry
• ADS: Implements Aggregated Service Discovery (ADS)
• SDS: Implements Secret Discovery Service (SDS) example
• Virtual API Gateway: Setup envoy ingress gateways via annotations
• Health Checks:
• Multi-Tenancy:
• Multi-Source: Kubernetes, DNS, file watch, static

Usage

Create xDS server as show in this example using this SDK.

You run the service locally or in Kubernetes accompanied by config.yml:

make run-xds

This use your local kubeconfig, so if kubectl works then it should work, unless you use some sort of authentication plugin.

If you're running in cluster it should also work without any environment variables. It requires some read-only access, which you can find the ClusterRole in rbac.yml. It is recommended to deploy this as headless service. As it use DNS-based discovery, we recommend not to use autoscaling on this service but keep it always at max pods.

That's it! Your xDS server is ready.

Connecting to xDS from clients

You need to set xDS bootstrap config on your client application. Here's the xDS bootstrap file:

{
    "xds_servers": [
        {
            "server_uri": "localhost:5000",
            "channel_creds": [{"type": "insecure"}],
            "server_features": ["xds_v3"]
        }
    ],
    "node": {
        "id": "anything",
        "locality": {
            "zone" : "k8s"
        }
    }
}

Make sure to change server_url to wherever your application can access this xDS server. You then can supply this to your application in two methods:

• Put the entire JSON in GRPC_XDS_BOOTSTRAP_CONFIG environment variable
• Put the entire JSON in a file, then point GRPC_XDS_BOOTSTRAP environment variable to its path Then follow the language specific instructions to enable xDS.

Finally, if you were connecting to appname.appns:8080 write your connection string as xds:///appname.appns:8080 instead. Note the triple slash and that the namespace is not optional. (As this doesn't use DNS)

Go

Add this somewhere, maybe in your main file

import _ "google.golang.org/grpc/xds"

JavaScript

Install @grpc/grpc-js-xds then run

require('@grpc/grpc-js-xds').register();

Java

You need to add grpc-xds dependency along with the common grpc dependencies. gradle example

    implementation(libs.grpc.protobuf)
    implementation(libs.grpc.kotlin.stub)
    implementation(libs.grpc.services) // includes grpc-protobuf
    implementation(libs.grpc.xds) // includes grpc-services, grpc-auth,  grpc-alts

Then a new channel can be created with xds protocol.

Grpc.newChannelBuilder("xds:///{service}.{namespace}:{port}", InsecureChannelCredentials.create())

Note: the serviceConfigLookUp should not be disabled otherwise the xds protocol does not works correctly.

Since environment variable cannot be changed in java, there are 2 system properties which overrides the common bootstrap variables:

• io.grpc.xds.bootstrap to override GRPC_XDS_BOOTSTRAP
• io.grpc.xds.bootstrapConfig to override GRPC_XDS_BOOTSTRAP_CONFIG

Virtual API Gateway

One feature of xDS is routing. This xDS server supports virtual API gateway by adding the following annotations to Kubernetes service:

apiVersion: v1
kind: Service
metadata:
  # ...
  annotations:
    xds.chinthagunta.io/api-gateway: apigw1,apigw2
    xds.chinthagunta.io/grpc-service: package.name.ExampleService,package.name.Example2Service

The service also must have a port named grpc, which traffic will be sent to.

Then client applications (with xDS support) can connect to xds:///apigw1 or xds:///apigw2 (no port or namespace) and any API calls to gRPC service package.name.ExampleService and package.name.Example2Service will be sent to this service.