Make datastore tests pass with remote Docker containers (#587)

* Make datastore tests pass with remote Docker containers
* Make tests consume DOCKER_HOST IP address as bind host while constucting database URI.

 This fix makes datastore tests pass against
 remote Docker (with host IP different from 127.0.0.1)

Fixes: #586

* Make datastore tests pass on Go1.7.1

api/datastore/internal/datastoretest/test.go

@@ -12,6 +12,9 @@ import (
 	"github.com/gin-gonic/gin"
 	"reflect"
 	"net/http"
+	"os"
+	"net/url"
+	"strings"
 )
 
 func setLogBuffer() *bytes.Buffer {
@@ -24,6 +27,28 @@ func setLogBuffer() *bytes.Buffer {
 	return &buf
 }
 
+// workaround for parts.Hostname() that doesn't work on Go1.7.1
+// TODO(denismakogon): remove this after switching to Go 1.8
+func stripPort(hostport string) string {
+	colon := strings.IndexByte(hostport, ':')
+	if colon == -1 {
+		return hostport
+	}
+	if i := strings.IndexByte(hostport, ']'); i != -1 {
+		return strings.TrimPrefix(hostport[:i], "[")
+	}
+	return hostport[:colon]
+}
+
+func GetContainerHostIP() string {
+	dockerHost := os.Getenv("DOCKER_HOST")
+	if dockerHost == "" {
+		return "127.0.0.1"
+	}
+	parts, _ := url.Parse(dockerHost)
+	return stripPort(parts.Host)
+}
+
 func Test(t *testing.T, ds models.Datastore) {
 	buf := setLogBuffer()