Read the channel from the local filesystem during tests

Another step towards working totally offline (which may never be fully
achievable, because of the need to hash assets).  But should ensure that
when we update the stable channel, we are testing against that version
in the tests, otherwise it is easy to break master.

pkg/apis/kops/channel.go

@@ -27,7 +27,8 @@ import (
 	"net/url"
 )
 
-const DefaultChannelBase = "https://raw.githubusercontent.com/kubernetes/kops/master/channels/"
+var DefaultChannelBase = "https://raw.githubusercontent.com/kubernetes/kops/master/channels/"
+
 const DefaultChannel = "stable"
 const AlphaChannel = "alpha"
 

pkg/testutils/integrationtestharness.go

@@ -24,15 +24,21 @@ import (
 	"io/ioutil"
 	"k8s.io/kops/cloudmock/aws/mockec2"
 	"k8s.io/kops/cloudmock/aws/mockroute53"
+	"k8s.io/kops/pkg/apis/kops"
 	"k8s.io/kops/upup/pkg/fi/cloudup/awsup"
 	"k8s.io/kops/util/pkg/vfs"
 	"os"
+	"path"
+	"path/filepath"
 	"testing"
 )
 
 type IntegrationTestHarness struct {
 	TempDir string
 	T       *testing.T
+
+	// The original kops DefaultChannelBase value, restored on Close
+	originalDefaultChannelBase string
 }
 
 func NewIntegrationTestHarness(t *testing.T) *IntegrationTestHarness {
@@ -45,6 +51,17 @@ func NewIntegrationTestHarness(t *testing.T) *IntegrationTestHarness {
 
 	vfs.Context.ResetMemfsContext(true)
 
+	// Replace the default channel path with a local filesystem path, so we don't try to retrieve it from a server
+	{
+		channelPath, err := filepath.Abs(path.Join("../../channels/"))
+		if err != nil {
+			t.Fatalf("error resolving stable channel path: %v", err)
+		}
+		channelPath += "/"
+		h.originalDefaultChannelBase = kops.DefaultChannelBase
+		kops.DefaultChannelBase = "file://" + channelPath
+	}
+
 	return h
 }
 
@@ -59,6 +76,10 @@ func (h *IntegrationTestHarness) Close() {
 			}
 		}
 	}
+
+	if h.originalDefaultChannelBase != "" {
+		kops.DefaultChannelBase = h.originalDefaultChannelBase
+	}
 }
 
 func (h *IntegrationTestHarness) SetupMockAWS() {