From f106de0efd7bae8d5f5f90fc51e68460961a5969 Mon Sep 17 00:00:00 2001
From: Marcus Efraimsson <marcus.efraimsson@gmail.com>
Date: Thu, 7 Jun 2018 15:15:13 +0200
Subject: [PATCH] enhance error message if phantomjs executable is not found

if arm build, explain that phantomjs is not included by default in arm
builds. If not explain that phantom js isn't installed correctly
---
 pkg/api/render.go                   | 11 +++++++++++
 pkg/services/rendering/interface.go |  1 +
 pkg/services/rendering/phantomjs.go |  5 +++++
 3 files changed, 17 insertions(+)

diff --git a/pkg/api/render.go b/pkg/api/render.go
index f6f149980d6..b8ef6cc5cb6 100644
--- a/pkg/api/render.go
+++ b/pkg/api/render.go
@@ -3,7 +3,9 @@ package api
 import (
 	"fmt"
 	"net/http"
+	"runtime"
 	"strconv"
+	"strings"
 	"time"
 
 	m "github.com/grafana/grafana/pkg/models"
@@ -55,6 +57,15 @@ func (hs *HTTPServer) RenderToPng(c *m.ReqContext) {
 		return
 	}
 
+	if err != nil && err == rendering.ErrPhantomJSNotInstalled {
+		if strings.HasPrefix(runtime.GOARCH, "arm") {
+			c.Handle(500, "Rendering failed - PhantomJS isn't included in arm build per default", err)
+		} else {
+			c.Handle(500, "Rendering failed - PhantomJS isn't installed correctly", err)
+		}
+		return
+	}
+
 	if err != nil {
 		c.Handle(500, "Rendering failed.", err)
 		return
diff --git a/pkg/services/rendering/interface.go b/pkg/services/rendering/interface.go
index 9498071f264..85c139cfc04 100644
--- a/pkg/services/rendering/interface.go
+++ b/pkg/services/rendering/interface.go
@@ -10,6 +10,7 @@ import (
 
 var ErrTimeout = errors.New("Timeout error. You can set timeout in seconds with &timeout url parameter")
 var ErrNoRenderer = errors.New("No renderer plugin found nor is an external render server configured")
+var ErrPhantomJSNotInstalled = errors.New("PhantomJS executable not found")
 
 type Opts struct {
 	Width    int
diff --git a/pkg/services/rendering/phantomjs.go b/pkg/services/rendering/phantomjs.go
index d4ceac0ed43..8e06b5fed9d 100644
--- a/pkg/services/rendering/phantomjs.go
+++ b/pkg/services/rendering/phantomjs.go
@@ -24,6 +24,11 @@ func (rs *RenderingService) renderViaPhantomJS(ctx context.Context, opts Opts) (
 
 	url := rs.getURL(opts.Path)
 	binPath, _ := filepath.Abs(filepath.Join(rs.Cfg.PhantomDir, executable))
+	if _, err := os.Stat(binPath); os.IsNotExist(err) {
+		rs.log.Error("executable not found", "executable", binPath)
+		return nil, ErrPhantomJSNotInstalled
+	}
+
 	scriptPath, _ := filepath.Abs(filepath.Join(rs.Cfg.PhantomDir, "render.js"))
 	pngPath := rs.getFilePathForNewImage()