Health checker for Docker Swarm nodes

health.go

package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"github.com/docker/swarmkit/api"
	"github.com/docker/swarmkit/ca"
	"github.com/docker/swarmkit/manager"
	"google.golang.org/grpc"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Printf("must pass in node address with port (e.g. 123.123.123.123:2377) as the first argument")
		return
	}
	nodeCertPaths := ca.CertPaths{
		Cert: "/var/lib/docker/swarm/certificates/swarm-node.crt",
		Key:  "/var/lib/docker/swarm/certificates/swarm-node.key",
	}
	certPaths := ca.CertPaths{
		Cert: "/var/lib/docker/swarm/certificates/swarm-root-ca.crt",
		Key:  "/var/lib/docker/swarm/certificates/swarm-root-ca.key",
	}
	rootCA, err := ca.GetLocalRootCA(certPaths)
	if err != nil {
		fmt.Printf("could not load CA: %s\n", err)
		return
	}
	var unlockKey []byte
	krw := ca.NewKeyReadWriter(nodeCertPaths, unlockKey, &manager.RaftDEKData{})
	securityConfig, err := ca.LoadSecurityConfig(context.TODO(), rootCA, krw, false)
	if err != nil {
		fmt.Printf("could not load security config: %s\n", err)
		return
	}
	grpcOptions := []grpc.DialOption{
		grpc.WithBackoffMaxDelay(8 * time.Second),
		grpc.WithTransportCredentials(securityConfig.ClientTLSCreds),
		grpc.WithTimeout(2 * time.Second),
	}

	cc, err := grpc.Dial(os.Args[1], grpcOptions...)
	if err != nil {
		fmt.Printf("failed to dial to grpc: %s\n", err)
		return
	}

	resp, err := api.NewHealthClient(cc).Check(context.TODO(), &api.HealthCheckRequest{Service: "Raft"})
	if err != nil {
		fmt.Printf("failed to check health: %s\n", err)
		return
	}
	fmt.Printf("got a health check response: %+v\n", resp)
}