How to Setup Kubernetes Health Checking for gRPC with NodeJs And Bazel? (grpc-health-probe)

Question

How to setup GRPC Health Checking for gRPC with Node.js an Bazel?

Answer 1

1. Add the grpc-health-probe binary to Bazel

In your WORKSPACE file add

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")

http_file(
    name = "grpc_health_check_bin",
    downloaded_file_path = "grpc_health_probe",
    urls = ["https://github.com/grpc-ecosystem/grpc-health-probe/releases/download/v0.3.2/grpc_health_probe-linux-amd64"],
)

to download the executable binary.

2. Implement Service

Option 1: Use the grpc-health-check npm module

• just read the docs :)

Option 2 Implement the Health service yourself

1. Go to this page and copy the health-checking.proto file, which currently looks like this:

   syntax = "proto3";
   
   package grpc.health.v1;
   
   message HealthCheckRequest {
     string service = 1;
   }
   
   message HealthCheckResponse {
     enum ServingStatus {
       UNKNOWN = 0;
       SERVING = 1;
       NOT_SERVING = 2;
       SERVICE_UNKNOWN = 3;  // Used only by the Watch method.
     }
     ServingStatus status = 1;
   }
   
   service Health {
     rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
   
     rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
   }
   

2. In your BUILD.bazel file create a filegroup with the proto file, such that we can later add it to the NodeJs image

   filegroup(
       name = "health_checking_proto",
       srcs = ["health-checking.proto"],
   )
   

3. Implement the Health service

   import * as protoLoader from '@grpc/proto-loader'
   import * as grpc from '@grpc/grpc-js'
   
   async function main() {
     const packageDefinition = await protoLoader.load('health-checking.proto')
     const grpcObject = grpc.loadPackageDefinition(packageDefinition)
     const {service} = (grpcObject.grpc as any).health.v1.Health
   
     const server = new grpc.Server()
     const implementation = {
       // status can be on of UNKNOWN, SERVING, NOT_SERVING
       Check: (_call: any, callback: any) => callback(null, {status: 'SERVING'}),
     }
     server.addService(service, implementation)
   
     server.bindAsync('0.0.0.0:9090', grpc.ServerCredentials.createInsecure(), () => server.start())
   }
   
   main()
   

3. Build and Deploy the NodeJs image with Bazel

The final BUILD file might look like this:

load("@npm//@bazel/typescript:index.bzl", "ts_library")
load("@k8s_deploy//:defaults.bzl", "k8s_deploy")
load("@io_bazel_rules_docker//nodejs:image.bzl", "nodejs_image")

package(default_visibility = ["//visibility:public"])

ts_library(
    name = "lib",
    srcs = glob(include = ["**/*.ts"]),
    deps = [
        "@npm//@grpc/grpc-js",
        "@npm//@grpc/proto-loader",
        "@npm//@types/node",
    ],
)

filegroup(
    name = "health_checking_proto",
    srcs = ["health-checking.proto"],
)

nodejs_image(
    name = "image",
    data = [
        # nodejs application
        ":lib",
        # health-checking.proto file
        ":health_checking_proto",
        # grpc-health-probe executable binary
        "@grpc_health_check_bin//file",
    ],
    entry_point = ":index.ts",
)

k8s_deploy(
    name = "k8s",
    images = {"k8s:placeholder_name": ":image"},
    template = ":k8s.yaml",
)

4. Add Liveness and Readiness Probes to Kubernetes

spec:
  containers:
  - name: server
    image: "[YOUR-DOCKER-IMAGE]"
    ports:
    - containerPort: 9090
    readinessProbe:
      exec:
        command: ["/app/<path to dir with BUILD file>/image.binary.runfiles/grpc_health_check_bin/file/grpc_health_probe", "-addr=:9090"]
      initialDelaySeconds: 5
    livenessProbe:
      exec:
        command: ["/app/<path to dir with BUILD file>/image.binary.runfiles/grpc_health_check_bin/file/grpc_health_probe", "-addr=:9090"]
      initialDelaySeconds: 10