fix(server): timeout and fetch version concurrently

fixes an issue where version was not being fetched concurrently
and not timing out for each source.

Co-authored-by: Kelvin Wang <sherkrainwang@gmail.com>

flux/client.go

@@ -62,8 +62,9 @@ func (c *Client) FluxEnabled() (bool, error) {
 	if err != nil {
 		return false, err
 	}
-
-	hc := &http.Client{}
+	hc := &http.Client{
+		Timeout: c.Timeout,
+	}
 	if c.InsecureSkipVerify {
 		hc.Transport = skipVerifyTransport
 	} else {

server/sources.go

@@ -2,12 +2,12 @@ package server
 
 import (
 	"context"
+	"crypto/tls"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
 	"time"
-	"crypto/tls"
 
 	"github.com/influxdata/chronograf/enterprise"
 	"github.com/influxdata/chronograf/flux"
@@ -31,7 +31,7 @@ type sourceLinks struct {
 	Databases   string `json:"databases"`       // URL for the databases contained within this source
 	Annotations string `json:"annotations"`     // URL for the annotations of this source
 	Health      string `json:"health"`          // URL for source health
-	Flux		string `json:"flux,omitempty"`  // URL for flux if it exists
+	Flux        string `json:"flux,omitempty"`  // URL for flux if it exists
 }
 
 type sourceResponse struct {
@@ -76,8 +76,7 @@ var (
 	skipVerifyTransport = &http.Transport{
 		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
 	}
-	defaultTransport = &http.Transport{
-	}
+	defaultTransport = &http.Transport{}
 )
 
 func hasFlux(ctx context.Context, src chronograf.Source) (bool, error) {
@@ -87,8 +86,8 @@ func hasFlux(ctx context.Context, src chronograf.Source) (bool, error) {
 	}
 
 	cli := &flux.Client{
-		URL: url,
-		Timeout: 500 *time.Millisecond,
+		URL:     url,
+		Timeout: 500 * time.Millisecond,
 	}
 
 	return cli.FluxEnabled()
@@ -215,6 +214,10 @@ func (s *Service) tsdbType(ctx context.Context, src *chronograf.Source) (string,
 	if err := cli.Connect(ctx, src); err != nil {
 		return "", err
 	}
+
+	ctx, cancel := context.WithTimeout(ctx, time.Second)
+	defer cancel()
+
 	return cli.Type(ctx)
 }
 
@@ -225,29 +228,32 @@ type getSourcesResponse struct {
 // Sources returns all sources from the store.
 func (s *Service) Sources(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
+
+	res := getSourcesResponse{
+		Sources: make([]sourceResponse, 0),
+	}
+
 	srcs, err := s.Store.Sources(ctx).All(ctx)
 	if err != nil {
 		Error(w, http.StatusInternalServerError, "Error loading sources", s.Logger)
 		return
 	}
 
-	res := getSourcesResponse{
-		Sources: make([]sourceResponse, len(srcs)),
-	}
-
-	sources := make([]sourceResponse, 0)
+	sourceCh := make(chan sourceResponse, len(srcs))
 	for _, src := range srcs {
-		dbVersion, err := s.tsdbVersion(ctx, &src)
-		if err != nil {
-			dbVersion = "Unknown"
-			s.Logger.WithField("error", err.Error()).Info("Failed to retrieve database version")
-		}
-		src.Version = dbVersion
-
-		sources = append(sources, newSourceResponse(ctx, src))
+		go func(src chronograf.Source) {
+			dbVersion, err := s.tsdbVersion(ctx, &src)
+			if err != nil {
+				dbVersion = "Unknown"
+				s.Logger.WithField("error", err.Error()).Info("Failed to retrieve database version")
+			}
+			src.Version = dbVersion
+			sourceCh <- newSourceResponse(ctx, src)
+		}(src)
+	}
+	for i := 0; i < len(srcs); i++ {
+		res.Sources = append(res.Sources, <-sourceCh)
 	}
-
-	res.Sources = sources
 
 	encodeJSON(w, http.StatusOK, res, s.Logger)
 }