Add customizable endpoints ('/debug/vars')

expvars.go

@@ -11,8 +11,8 @@ import (
 	"github.com/antonholmquist/jason"
 )
 
-// ExpvarsUrl is the default url for fetching expvar info.
-const ExpvarsPath = "/debug/vars"
+// DefaultEndpoint is the default url for fetching expvar info.
+var DefaultEndpoint = "/debug/vars"
 
 // Expvar represents fetched expvar variable.
 type Expvar struct {

main.go

@@ -17,12 +17,15 @@ var (
 	varsArg  = flag.String("vars", "mem:memstats.Alloc,mem:memstats.Sys,mem:memstats.HeapAlloc,mem:memstats.HeapInuse,duration:memstats.PauseNs,duration:memstats.PauseTotalNs", "Vars to monitor (comma-separated)")
 	dummy    = flag.Bool("dummy", false, "Use dummy (console) output")
 	self     = flag.Bool("self", false, "Monitor itself")
+	endpoint = flag.String("endpoint", DefaultEndpoint, "URL endpoint for expvars")
 )
 
 func main() {
 	flag.Usage = Usage
 	flag.Parse()
 
+	DefaultEndpoint = *endpoint
+
 	// Process ports/urls
 	ports, _ := ParsePorts(*urls)
 	if *self {

utils.go

@@ -53,7 +53,9 @@ func flattenURLs(rawurl string, ports []string) ([]url.URL, error) {
 	if err != nil {
 		return nil, err
 	}
-	baseUrl.Path = ExpvarsPath
+	if baseUrl.Path == "" {
+		baseUrl.Path = DefaultEndpoint
+	}
 
 	// Create new URL for each port
 	for _, port := range ports {
@@ -69,35 +71,9 @@ func ParsePorts(s string) ([]url.URL, error) {
 	var urls []url.URL
 	fields := strings.FieldsFunc(s, func(r rune) bool { return r == ',' })
 	for _, field := range fields {
-		// Try simple 'ports range' mode, ports only ("1234-1235,80")
-		// Defaults to "localhost" will be used.
-		ports, err := parseRange(field)
-		if err == nil {
-			furls, err := flattenURLs("http://localhost", ports)
-			if err != nil {
-				return nil, err
-			}
-			urls = append(urls, furls...)
-			continue
-		}
+		rawurl, portsRange := extractUrlAndPorts(field)
 
-		// then, try host:ports notation ("localhost:1234-1235,https://remote:2000,2345")
-		var rawurl, portsRange string
-		parts := strings.FieldsFunc(field, func(r rune) bool { return r == ':' })
-		switch len(parts) {
-		case 1:
-			// "1234-234"
-			rawurl = "http://localhost"
-		case 2:
-			// "localhost:1234"
-			rawurl, portsRange = parts[0], parts[1]
-		default:
-			// "https://user:pass@remote.name:1234"
-			rawurl = strings.Join(parts[:len(parts)-1], ":")
-			portsRange = parts[len(parts)-1]
-		}
-
-		ports, err = parseRange(portsRange)
+		ports, err := parseRange(portsRange)
 		if err != nil {
 			return nil, ErrParsePorts
 		}
@@ -113,6 +89,42 @@ func ParsePorts(s string) ([]url.URL, error) {
 	return urls, nil
 }
 
+// extractUrlAndPorts attempts to split url and extract raw url
+// for the single port and range of ports to parse.
+//
+// i.e. "http://name:1234-1236/_endpoint" would return "http://name/_endpoint" and
+// "1234-1236"
+func extractUrlAndPorts(s string) (string, string) {
+	var rawurl, ports string
+	parts := strings.Split(s, ":")
+	switch len(parts) {
+	case 1:
+		// "1234-234"
+		rawurl = "http://localhost"
+		ports = parts[0]
+	case 2:
+		// "localhost:1234"
+		rawurl, ports = parts[0], parts[1]
+	default:
+		// "https://user:pass@remote.name:1234" or "http://name:1234-1236/_endpoint"
+
+		// construct endpoint from the first part of URI, before ports appera
+		rawurl = strings.Join(parts[:len(parts)-1], ":")
+
+		// get either "1234-1235" or "1234-1235/_endpoint"
+		lastPart := parts[len(parts)-1]
+
+		// try to find endpoint and attach it to rawurl
+		fields := strings.SplitN(lastPart, "/", 2)
+		ports = fields[0]
+		if len(fields) > 1 {
+			rawurl = fmt.Sprintf("%s/%s", rawurl, fields[1])
+		}
+	}
+
+	return rawurl, ports
+}
+
 // parseRange flattens port ranges, such as "1234-1240,1333"
 func parseRange(s string) ([]string, error) {
 	portsInt, err := ranges.Parse(s)

utils_test.go

@@ -26,6 +26,29 @@ func TestUtils(t *testing.T) {
 	}
 }
 
+func TestExtractUrlAndPorts(t *testing.T) {
+	var rawurl, ports string
+	rawurl, ports = extractUrlAndPorts("40000-40002")
+	if rawurl != "http://localhost" || ports != "40000-40002" {
+		t.Fatalf("extract url and ports failed: %v, %v", rawurl, ports)
+	}
+
+	rawurl, ports = extractUrlAndPorts("https://example.com:1234")
+	if rawurl != "https://example.com" || ports != "1234" {
+		t.Fatalf("extract url and ports failed: %v, %v", rawurl, ports)
+	}
+
+	rawurl, ports = extractUrlAndPorts("http://user:passwd@example.com:1234-1256")
+	if rawurl != "http://user:passwd@example.com" || ports != "1234-1256" {
+		t.Fatalf("extract url and ports failed: %v, %v", rawurl, ports)
+	}
+
+	rawurl, ports = extractUrlAndPorts("https://example.com:1234-1256/_endpoint")
+	if rawurl != "https://example.com/_endpoint" || ports != "1234-1256" {
+		t.Fatalf("extract url and ports failed: %v, %v", rawurl, ports)
+	}
+}
+
 func TestPorts(t *testing.T) {
 	arg := "1234,1235"
 	ports, err := ParsePorts(arg)
@@ -85,4 +108,14 @@ func TestPorts(t *testing.T) {
 	if err == nil {
 		t.Fatalf("err shouldn't be nil")
 	}
+
+	// Test endpoints
+	arg = "localhost:2000,https://example.com:1234/_custom_expvars"
+	ports, err = ParsePorts(arg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ports[0].Path != "/debug/vars" || ports[1].Path != "/_custom_expvars" {
+		t.Fatalf("ParsePorts returns wrong data: %v", ports)
+	}
 }