Create 2 files: main.go and docker-compose.yml. Once both are created use docker-compose up and it will build the necessary files and start Elastic Search.
I found it necessary to add elastic.SetSniff(false) or I could not connect. Also remember the docker containers have security enabled for Elasticsearch with the password set as elastic:changeme. You can test it using curl:
curl http://127.0.0.1:9200/_cat/health -u elastic:changemeOnce it is running you can successfully run the main.go file using go run main.go.
To reset everything or upgrade to the latest version of Elastic Search, use docker-compose down -v
Use the following for your docker-compose.yml
version: "2.2"
services:
elasticsearch:
image: docker.elastic.co/elasticsearch/elasticsearch:5.6.3
container_name: elasticsearch
environment:
- cluster.name=docker-cluster
- bootstrap.memory_lock=true
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
ulimits:
memlock:
soft: -1
hard: -1
volumes:
- esdata1:/usr/share/elasticsearch/data
ports:
- 9200:9200
networks:
- esnet
elasticsearch2:
image: docker.elastic.co/elasticsearch/elasticsearch:5.6.3
container_name: elasticsearch2
environment:
- cluster.name=docker-cluster
- bootstrap.memory_lock=true
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
- "discovery.zen.ping.unicast.hosts=elasticsearch"
ulimits:
memlock:
soft: -1
hard: -1
volumes:
- esdata2:/usr/share/elasticsearch/data
networks:
- esnet
volumes:
esdata1:
driver: local
esdata2:
driver: local
networks:
esnet:
The following code comes from https://olivere.github.io/elastic/
package main
import (
"context"
"encoding/json"
"fmt"
"reflect"
"time"
elastic "gopkg.in/olivere/elastic.v5"
)
// Tweet is a structure used for serializing/deserializing data in Elasticsearch.
type Tweet struct {
User string `json:"user"`
Message string `json:"message"`
Retweets int `json:"retweets"`
Image string `json:"image,omitempty"`
Created time.Time `json:"created,omitempty"`
Tags []string `json:"tags,omitempty"`
Location string `json:"location,omitempty"`
Suggest *elastic.SuggestField `json:"suggest_field,omitempty"`
}
const mapping = `
{
"settings":{
"number_of_shards": 3,
"number_of_replicas": 1
},
"mappings":{
"tweet":{
"properties":{
"user":{
"type":"keyword"
},
"message":{
"type":"text",
"store": true,
"fielddata": true
},
"image":{
"type":"keyword"
},
"created":{
"type":"date"
},
"tags":{
"type":"keyword"
},
"location":{
"type":"geo_point"
},
"suggest_field":{
"type":"completion"
}
}
}
}
}`
func main() {
// Starting with elastic.v5, you must pass a context to execute each service
ctx := context.Background()
// Obtain a client and connect to the default Elasticsearch installation
// on 127.0.0.1:9200. Of course you can configure your client to connect
// to other hosts and configure it in various other ways.
client, err := elastic.NewClient(elastic.SetSniff(false), elastic.SetURL("http://127.0.0.1:9200"), elastic.SetBasicAuth("elastic", "changeme"))
if err != nil {
// Handle error
panic(err)
}
// Ping the Elasticsearch server to get e.g. the version number
info, code, err := client.Ping("http://127.0.0.1:9200").Do(ctx)
if err != nil {
// Handle error
panic(err)
}
fmt.Printf("Elasticsearch returned with code %d and version %s\n", code, info.Version.Number)
// Getting the ES version number is quite common, so there's a shortcut
esversion, err := client.ElasticsearchVersion("http://127.0.0.1:9200")
if err != nil {
// Handle error
panic(err)
}
fmt.Printf("Elasticsearch version %s\n", esversion)
// Use the IndexExists service to check if a specified index exists.
exists, err := client.IndexExists("twitter").Do(ctx)
if err != nil {
// Handle error
panic(err)
}
if !exists {
// Create a new index.
createIndex, err := client.CreateIndex("twitter").BodyString(mapping).Do(ctx)
if err != nil {
// Handle error
panic(err)
}
if !createIndex.Acknowledged {
// Not acknowledged
}
}
// Index a tweet (using JSON serialization)
tweet1 := Tweet{User: "olivere", Message: "Take Five", Retweets: 0}
put1, err := client.Index().
Index("twitter").
Type("tweet").
Id("1").
BodyJson(tweet1).
Do(ctx)
if err != nil {
// Handle error
panic(err)
}
fmt.Printf("Indexed tweet %s to index %s, type %s\n", put1.Id, put1.Index, put1.Type)
// Index a second tweet (by string)
tweet2 := `{"user" : "olivere", "message" : "It's a Raggy Waltz"}`
put2, err := client.Index().
Index("twitter").
Type("tweet").
Id("2").
BodyString(tweet2).
Do(ctx)
if err != nil {
// Handle error
panic(err)
}
fmt.Printf("Indexed tweet %s to index %s, type %s\n", put2.Id, put2.Index, put2.Type)
// Get tweet with specified ID
get1, err := client.Get().
Index("twitter").
Type("tweet").
Id("1").
Do(ctx)
if err != nil {
// Handle error
panic(err)
}
if get1.Found {
fmt.Printf("Got document %s in version %d from index %s, type %s\n", get1.Id, get1.Version, get1.Index, get1.Type)
}
// Flush to make sure the documents got written.
_, err = client.Flush().Index("twitter").Do(ctx)
if err != nil {
panic(err)
}
// Search with a term query
termQuery := elastic.NewTermQuery("user", "olivere")
searchResult, err := client.Search().
Index("twitter"). // search in index "twitter"
Query(termQuery). // specify the query
Sort("user", true). // sort by "user" field, ascending
From(0).Size(10). // take documents 0-9
Pretty(true). // pretty print request and response JSON
Do(ctx) // execute
if err != nil {
// Handle error
panic(err)
}
// searchResult is of type SearchResult and returns hits, suggestions,
// and all kinds of other information from Elasticsearch.
fmt.Printf("Query took %d milliseconds\n", searchResult.TookInMillis)
// Each is a convenience function that iterates over hits in a search result.
// It makes sure you don't need to check for nil values in the response.
// However, it ignores errors in serialization. If you want full control
// over iterating the hits, see below.
var ttyp Tweet
for _, item := range searchResult.Each(reflect.TypeOf(ttyp)) {
if t, ok := item.(Tweet); ok {
fmt.Printf("Tweet by %s: %s\n", t.User, t.Message)
}
}
// TotalHits is another convenience function that works even when something goes wrong.
fmt.Printf("Found a total of %d tweets\n", searchResult.TotalHits())
// Here's how you iterate through results with full control over each step.
if searchResult.Hits.TotalHits > 0 {
fmt.Printf("Found a total of %d tweets\n", searchResult.Hits.TotalHits)
// Iterate through results
for _, hit := range searchResult.Hits.Hits {
// hit.Index contains the name of the index
// Deserialize hit.Source into a Tweet (could also be just a map[string]interface{}).
var t Tweet
err := json.Unmarshal(*hit.Source, &t)
if err != nil {
// Deserialization failed
}
// Work with tweet
fmt.Printf("Tweet by %s: %s\n", t.User, t.Message)
}
} else {
// No hits
fmt.Print("Found no tweets\n")
}
// Update a tweet by the update API of Elasticsearch.
// We just increment the number of retweets.
update, err := client.Update().Index("twitter").Type("tweet").Id("1").
Script(elastic.NewScriptInline("ctx._source.retweets += params.num").Lang("painless").Param("num", 1)).
Upsert(map[string]interface{}{"retweets": 0}).
Do(ctx)
if err != nil {
// Handle error
panic(err)
}
fmt.Printf("New version of tweet %q is now %d\n", update.Id, update.Version)
// ...
// Delete an index.
deleteIndex, err := client.DeleteIndex("twitter").Do(ctx)
if err != nil {
// Handle error
panic(err)
}
if !deleteIndex.Acknowledged {
// Not acknowledged
}
for {
}
}