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README
go-elasticsearch
The official Go client for Elasticsearch.
Compatibility
Language clients are forward compatible; meaning that clients support communicating with greater or equal minor versions of Elasticsearch. Elasticsearch language clients are only backwards compatible with default distributions and without guarantees made.
When using Go modules, include the version in the import path, and specify either an explicit version or a branch:
require github.com/elastic/go-elasticsearch/v8 v8.0.0
require github.com/elastic/go-elasticsearch/v7 7.17
It's possible to use multiple versions of the client in a single project:
// go.mod
github.com/elastic/go-elasticsearch/v7 v7.17.0
github.com/elastic/go-elasticsearch/v8 v8.0.0
// main.go
import (
elasticsearch7 "github.com/elastic/go-elasticsearch/v7"
elasticsearch8 "github.com/elastic/go-elasticsearch/v8"
)
// ...
es7, _ := elasticsearch7.NewDefaultClient()
es8, _ := elasticsearch8.NewDefaultClient()
The main branch of the client is compatible with the current master branch of Elasticsearch.
<!-- ----------------------------------------------------------------------------------------------- -->
Installation
Add the package to your go.mod file:
require github.com/elastic/go-elasticsearch/v8 main
Or, clone the repository:
git clone --branch main https://github.com/elastic/go-elasticsearch.git $GOPATH/src/github.com/elastic/go-elasticsearch
A complete example:
mkdir my-elasticsearch-app && cd my-elasticsearch-app
cat > go.mod <<-END
module my-elasticsearch-app
require github.com/elastic/go-elasticsearch/v8 main
END
cat > main.go <<-END
package main
import (
"log"
"github.com/elastic/go-elasticsearch/v8"
)
func main() {
es, _ := elasticsearch.NewDefaultClient()
log.Println(elasticsearch.Version)
log.Println(es.Info())
}
END
go run main.go
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Usage
The elasticsearch package ties together two separate packages for calling the Elasticsearch APIs and transferring data over HTTP: esapi and elastictransport, respectively.
Use the elasticsearch.NewDefaultClient() function to create the client with the default settings.
es, err := elasticsearch.NewDefaultClient()
if err != nil {
log.Fatalf("Error creating the client: %s", err)
}
res, err := es.Info()
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
log.Println(res)
// [200 OK] {
// "name" : "node-1",
// "cluster_name" : "go-elasticsearch"
// ...
NOTE: It is critical to both close the response body and to consume it, in order to re-use persistent TCP connections in the default HTTP transport. If you're not interested in the response body, call
io.Copy(ioutil.Discard, res.Body).
When you export the ELASTICSEARCH_URL environment variable,
it will be used to set the cluster endpoint(s). Separate multiple addresses by a comma.
To set the cluster endpoint(s) programmatically, pass a configuration object
to the elasticsearch.NewClient() function.
cfg := elasticsearch.Config{
Addresses: []string{
"https://localhost:9200",
"https://localhost:9201",
},
// ...
}
es, err := elasticsearch.NewClient(cfg)
To set the username and password, include them in the endpoint URL, or use the corresponding configuration options.
cfg := elasticsearch.Config{
// ...
Username: "foo",
Password: "bar",
}
To set a custom certificate authority used to sign the certificates of cluster nodes,
use the CACert configuration option.
cert, _ := ioutil.ReadFile(*cacert)
cfg := elasticsearch.Config{
// ...
CACert: cert,
}
To set a fingerprint to validate the HTTPS connectionm use the CertificateFingerprint configuration option.
cfg := elasticsearch.Config{
// ...
CertificateFingerprint: fingerPrint,
}
To configure other HTTP settings, pass an http.Transport
object in the configuration object.
cfg := elasticsearch.Config{
Transport: &http.Transport{
MaxIdleConnsPerHost: 10,
ResponseHeaderTimeout: time.Second,
TLSClientConfig: &tls.Config{
MinVersion: tls.VersionTLS12,
// ...
},
// ...
},
}
See the [_examples/configuration.go](_examples/configuration.go) and
[_examples/customization.go](_examples/customization.go) files for
more examples of configuration and customization of the client.
See the [_examples/security](_examples/security) for an example of a security configuration.
The following example demonstrates a more complex usage. It fetches the Elasticsearch version from the cluster, indexes a couple of documents concurrently, and prints the search results, using a lightweight wrapper around the response body.
// $ go run _examples/main.go
package main
import (
"bytes"
"context"
"encoding/json"
"log"
"strconv"
"strings"
"sync"
"github.com/elastic/go-elasticsearch/v8"
"github.com/elastic/go-elasticsearch/v8/esapi"
)
func main() {
log.SetFlags(0)
var (
r map[string]interface{}
wg sync.WaitGroup
)
// Initialize a client with the default settings.
//
// An `ELASTICSEARCH_URL` environment variable will be used when exported.
//
es, err := elasticsearch.NewDefaultClient()
if err != nil {
log.Fatalf("Error creating the client: %s", err)
}
// 1. Get cluster info
//
res, err := es.Info()
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
// Check response status
if res.IsError() {
log.Fatalf("Error: %s", res.String())
}
// Deserialize the response into a map.
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
}
// Print client and server version numbers.
log.Printf("Client: %s", elasticsearch.Version)
log.Printf("Server: %s", r["version"].(map[string]interface{})["number"])
log.Println(strings.Repeat("~", 37))
// 2. Index documents concurrently
//
for i, title := range []string{"Test One", "Test Two"} {
wg.Add(1)
go func(i int, title string) {
defer wg.Done()
// Build the request body.
data, err := json.Marshal(struct{ Title string }{Title: title})
if err != nil {
log.Fatalf("Error marshaling document: %s", err)
}
// Set up the request object.
req := esapi.IndexRequest{
Index: "test",
DocumentID: strconv.Itoa(i + 1),
Body: bytes.NewReader(data),
Refresh: "true",
}
// Perform the request with the client.
res, err := req.Do(context.Background(), es)
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
if res.IsError() {
log.Printf("[%s] Error indexing document ID=%d", res.Status(), i+1)
} else {
// Deserialize the response into a map.
var r map[string]interface{}
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Printf("Error parsing the response body: %s", err)
} else {
// Print the response status and indexed document version.
log.Printf("[%s] %s; version=%d", res.Status(), r["result"], int(r["_version"].(float64)))
}
}
}(i, title)
}
wg.Wait()
log.Println(strings.Repeat("-", 37))
// 3. Search for the indexed documents
//
// Build the request body.
var buf bytes.Buffer
query := map[string]interface{}{
"query": map[string]interface{}{
"match": map[string]interface{}{
"title": "test",
},
},
}
if err := json.NewEncoder(&buf).Encode(query); err != nil {
log.Fatalf("Error encoding query: %s", err)
}
// Perform the search request.
res, err = es.Search(
es.Search.WithContext(context.Background()),
es.Search.WithIndex("test"),
es.Search.WithBody(&buf),
es.Search.WithTrackTotalHits(true),
es.Search.WithPretty(),
)
if err != nil {
log.Fatalf("Error getting response: %s", err)
}
defer res.Body.Close()
if res.IsError() {
var e map[string]interface{}
if err := json.NewDecoder(res.Body).Decode(&e); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
} else {
// Print the response status and error information.
log.Fatalf("[%s] %s: %s",
res.Status(),
e["error"].(map[string]interface{})["type"],
e["error"].(map[string]interface{})["reason"],
)
}
}
if err := json.NewDecoder(res.Body).Decode(&r); err != nil {
log.Fatalf("Error parsing the response body: %s", err)
}
// Print the response status, number of results, and request duration.
log.Printf(
"[%s] %d hits; took: %dms",
res.Status(),
int(r["hits"].(map[string]interface{})["total"].(map[string]interface{})["value"].(float64)),
int(r["took"].(float64)),
)
// Print the ID and document source for each hit.
for _, hit := range r["hits"].(map[string]interface{})["hits"].([]interface{}) {
log.Printf(" * ID=%s, %s", hit.(map[string]interface{})["_id"], hit.(map[string]interface{})["_source"])
}
log.Println(strings.Repeat("=", 37))
}
// Client: 8.0.0-SNAPSHOT
// Server: 8.0.0-SNAPSHOT
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// [201 Created] updated; version=1
// [201 Created] updated; version=1
// -------------------------------------
// [200 OK] 2 hits; took: 5ms
// * ID=1, map[title:Test One]
// * ID=2, map[title:Test Two]
// =====================================
As you see in the example above, the esapi package allows to call the Elasticsearch APIs in two distinct ways: either by creating a struct, such as IndexRequest, and calling its Do() method by passing it a context and the client, or by calling the Search() function on the client directly, using the option functions such as WithIndex(). See more information and examples in the
package documentation.
The elastictransport package handles the transfer of data to and from Elasticsearch, including retrying failed requests, keeping a connection pool, discovering cluster nodes and logging.
Read more about the client internals and usage in the following blog posts:
- https://www.elastic.co/blog/the-go-client-for-elasticsearch-introduction
- https://www.elastic.co/blog/the-go-client-for-elasticsearch-configuration-and-customization
- https://www.elastic.co/blog/the-go-client-for-elasticsearch-working-with-data
<!-- ----------------------------------------------------------------------------------------------- -->
Helpers
The esutil package provides convenience helpers for working with the client. At the moment, it provides the esutil.JSONReader() and the esutil.BulkIndexer helpers.
<!-- ----------------------------------------------------------------------------------------------- -->
Examples
The [_examples](./_examples) folder contains a number of recipes and comprehensive examples to get you started with the client, including configuration and customization of the client, using a custom certificate authority (CA) for security (TLS), mocking the transport for unit tests, embedding the client in a custom type, building queries, performing requests individually and in bulk, and parsing the responses.
<!-- ----------------------------------------------------------------------------------------------- -->
License
This software is licensed under the [Apache 2 license](./LICENSE). See [NOTICE](./NOTICE).
*Note that all licence references and agreements mentioned in the go-elasticsearch README section above
are relevant to that project's source code only.