Accessing an Elasticsearch Cluster Using Go

Preparations

• The CSS cluster is available.
• Ensure that the server running Go can communicate with the CSS cluster.
• Ensure that Go has been installed on the server. You can download Go from the official website: https://go.dev/dl/.

Connecting to a Non-Security Mode Cluster

Connect to a non-security mode cluster. The sample code is as follows:

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package main

import (
	"github.com/elastic/go-elasticsearch/v7"
	"log"
)

func main() {
	cfg := elasticsearch.Config{
		Addresses: []string{
			"http://HOST:9200/",
		},
	}

	es, _ := elasticsearch.NewClient(cfg)
	log.Println(es.Info())
}

In the information above, HOST indicates the internal IP address of a cluster node.

Connecting to a Security-Mode Cluster

• Connect to a security-mode cluster with HTTPS disabled. The sample code is as follows:

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  package main import ( "github.com/elastic/go-elasticsearch/v7" "log" ) func main() { cfg := elasticsearch.Config{ Addresses: []string{ "http://HOST:9200/", }, Username: "USERNAME", Password: "PASSWORD", } es, _ := elasticsearch.NewClient(cfg) log.Println(es.Info()) }

• Connect to a security cluster that has enabled HTTPS and does not use certificates. The sample code is as follows:

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  package main import ( "crypto/tls" "github.com/elastic/go-elasticsearch/v7" "log" "net/http" ) func main() { cfg := elasticsearch.Config{ Addresses: []string{ "https://HOST:9200/", }, Username: "USERNAME", Password: "PASSWORD", Transport: &http.Transport{ TLSClientConfig: &tls.Config{ InsecureSkipVerify: true, }, }, } es, _ := elasticsearch.NewClient(cfg) log.Println(es.Info()) }

• Connect to a security cluster that has enabled HTTPS and uses certificates. The sample code is as follows:

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  package main import ( "crypto/tls" "crypto/x509" "flag" "github.com/elastic/go-elasticsearch/v7" "io/ioutil" "log" "net" "net/http" "time" ) func main() { insecure := flag.Bool("insecure-ssl", false, "Accept/Ignore all server SSL certificates") flag.Parse() // Get the SystemCertPool, continue with an empty pool on error rootCAs, _ := x509.SystemCertPool() if rootCAs == nil { rootCAs = x509.NewCertPool() } // Read in the cert file certs, err := ioutil.ReadFile("/tmp/CloudSearchService.cer") if err != nil { log.Fatalf("Failed to append %q to RootCAs: %v", "xxx", err) } // Append our cert to the system pool if ok := rootCAs.AppendCertsFromPEM(certs); !ok { log.Println("No certs appended, using system certs only") } config := elasticsearch.Config{ Addresses: []string{ "https://HOST:9200/", }, Username: "USERNAME", Password: "PASSWORD", Transport: &http.Transport{ MaxIdleConnsPerHost: 10, ResponseHeaderTimeout: time.Second, DialContext: (&net.Dialer{ Timeout: 30 * time.Second, KeepAlive: 30 * time.Second, }).DialContext, TLSClientConfig: &tls.Config{ InsecureSkipVerify: *insecure, RootCAs: rootCAs, }, }, } es, _ := elasticsearch.NewClient(config) log.Println(elasticsearch.Version) log.Println(es.Info()) }

Running Code

Write the code above to the EsTest.gc file based on the cluster type and save the file to an independent directory. Run the following command in that directory to run the code:

go env -w GO111MODULE=on
go env -w GOPROXY=https://goproxy.io,direct 
go env -w GONOSUMDB=*

go mod init test
go mod tidy
go run EsTest.go