Update to Go 1.11 beta 3 and notes about minimal module awareness

This commit updates the README to include Go 1.11 beta 3.

We also add a few notes about "minimal module awareness" that has been
included in Go 1.10.3 and 1.9.7. Unfortunately, the `dep` tool is still
on its way to implement that.

* [Minimal module awareness in Go 1.10.3 and Go
1.9.7](https://go.googlesource.com/go/+/d4e21288e444d3ffd30d1a0737f15ea3fc3b8ad9)
* [Tracking implementation of "minimal module awareness" in dep](golang/dep#1963)

Author: olivere

README.md

@@ -3,22 +3,40 @@
 Go 1.11 comes with modules support. This repository is a testbed
 for modules support.
 
-In a nutshell:
+To use this package with Go 1.11 (beta3 as of now), do:
 
 ```
-$ go version
-go version go1.11beta2 darwin/amd64
+$ go get golang.org/dl/go1.11beta3
+$ go1.11beta3 download
+$ go1.11beta3 version
+go version go1.11beta3 darwin/amd64
 $ cat go.mod
 module github/elastic-with-go-modules
 
 require github.com/olivere/elastic/v6 v6.1.27
-$ go build
+$ go1.11beta3 build
 go: finding github.com/olivere/elastic/v6 v6.1.27
 go: downloading github.com/olivere/elastic/v6 v6.1.27
 $ ./elastic-with-go-modules
-Connection succeeded
-Elasticsearch version 6.3.2
+Go version is go1.11beta3
+Connecting to Elasticsearch succeeded and we're talking to version 6.3.2
+```
+
+To do the same with Go 1.10.3, do:
+
 ```
+$ go version
+go version go1.10.3 darwin/amd64
+$ go get -v ./...
+$ go build
+$ ./elastic-with-go-modules
+Go version is go1.10.3
+Connecting to Elasticsearch succeeded and we're talking to version 6.3.2
+```
+
+Notice that you *must* use Go 1.10.3 (or Go 1.9.7) because limited module support has only been [introduced in those versions](https://go.googlesource.com/go/+/d4e21288e444d3ffd30d1a0737f15ea3fc3b8ad9). Earlier versions of Go wouldn't find the import path `"github.com/olivere/elastic/v6"`.
+
+Unfortunately, tools like [`dep`](https://github.com/golang/dep) don't support this either as of writing this. Follow [#1962](https://github.com/golang/dep/issues/1962) and [this PR](https://github.com/golang/dep/pull/1963) to watch progress on "minimal module awareness".
 
 ## License
 

main.go

@@ -16,6 +16,8 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"os"
+	"runtime"
 
 	elastic "github.com/olivere/elastic/v6"
 )
@@ -32,18 +34,21 @@ func main() {
 		*url = "http://127.0.0.1:9200"
 	}
 
+	fmt.Printf("Go version is %s\n", runtime.Version())
+
 	// Create an Elasticsearch client
+	fmt.Print("Connecting to Elasticsearch ")
 	client, err := elastic.NewClient(elastic.SetURL(*url), elastic.SetSniff(*sniff))
 	if err != nil {
-		log.Fatal(err)
+		fmt.Printf("failed: %v", err)
+		os.Exit(1)
 	}
-
-	// Just a status message
-	fmt.Println("Connection succeeded")
+	fmt.Print("succeeded ")
 
 	version, err := client.ElasticsearchVersion(*url)
 	if err != nil {
-		log.Fatal(err)
+		fmt.Printf("but couldn't retrieve version: %v", err)
+		os.Exit(1)
 	}
-	fmt.Printf("Elasticsearch version %s\n", version)
+	fmt.Printf("and we're talking to version %s\n", version)
 }