test, integration: Add cluster primitives to integration framework

This further extends the integration framework to add some simple
primitives for building clusters. More complex primitives and patterns
can be added in the future, but this should serve the general cases.

integration/util.go

@@ -19,10 +19,15 @@ package integration
 
 import (
 	"fmt"
+	"net"
+	"net/url"
 	"path"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
+
+	errwrap "github.com/pkg/errors"
 )
 
 const (
@@ -73,3 +78,20 @@ func Code(code string) string {
 
 	return strings.Join(output, "\n")
 }
+
+// ParsePort parses a URL and returns the port that was found.
+func ParsePort(input string) (int, error) {
+	u, err := url.Parse(input)
+	if err != nil {
+		return 0, errwrap.Wrapf(err, "could not parse URL")
+	}
+	_, sport, err := net.SplitHostPort(u.Host)
+	if err != nil {
+		return 0, errwrap.Wrapf(err, "could not get port")
+	}
+	port, err := strconv.Atoi(sport)
+	if err != nil {
+		return 0, errwrap.Wrapf(err, "could not parse port")
+	}
+	return port, nil
+}