Allow for remote kustomize bases (#2269)

Kustomize will error if it can't find a base dependency, so it's safe for
Skaffold to assume that any base file that does not exist locally is intended
to be a remote path that can be ignored since Skaffold can't monitor remote
paths for changes.

Author: jmcclell

pkg/skaffold/deploy/kustomize.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"io"
 	"io/ioutil"
+	"os"
 	"os/exec"
 	"path/filepath"
 
@@ -167,6 +168,12 @@ func dependenciesForKustomization(dir string) ([]string, error) {
 	}
 
 	for _, base := range content.Bases {
+		// If the file  doesn't exist locally, we can assume it's a remote file and
+		// skip it, since we can't monitor remote files. Kustomize itself will
+		// handle invalid/missing files.
+		if !fileExistsLocally(base, dir) {
+			continue
+		}
 		baseDeps, err := dependenciesForKustomization(filepath.Join(dir, base))
 		if err != nil {
 			return nil, err
@@ -203,6 +210,17 @@ func joinPaths(root string, paths []string) []string {
 	return list
 }
 
+func fileExistsLocally(filename string, workingDir string) bool {
+	path := filename
+	if !filepath.IsAbs(filename) {
+		path = filepath.Join(workingDir, filename)
+	}
+	if _, err := os.Stat(path); err == nil {
+		return true
+	}
+	return false
+}
+
 // Dependencies lists all the files that can change what needs to be deployed.
 func (k *KustomizeDeployer) Dependencies() ([]string, error) {
 	return dependenciesForKustomization(k.KustomizePath)

pkg/skaffold/deploy/kustomize_test.go

@@ -161,6 +161,7 @@ func TestDependenciesForKustomization(t *testing.T) {
 		yaml        string
 		expected    []string
 		shouldErr   bool
+		createFiles map[string]string
 	}{
 		{
 			description: "resources",
@@ -204,16 +205,28 @@ func TestDependenciesForKustomization(t *testing.T) {
 			expected: []string{"kustomization.yaml", "secret1.file", "secret2.file", "secret3.file"},
 		},
 		{
-			description: "unknown base",
-			yaml:        `bases: [other]`,
-			shouldErr:   true,
+			description: "base exists locally",
+			yaml:        `bases: [base]`,
+			expected:    []string{"base/kustomization.yaml", "base/app.yaml", "kustomization.yaml"},
+			createFiles: map[string]string{
+				"base/kustomization.yaml": `resources: [app.yaml]`,
+			},
+		},
+		{
+			description: "missing base locally",
+			yaml:        `bases: [missing-or-remote-base]`,
+			expected:    []string{"kustomization.yaml"},
 		},
 	}
 	for _, test := range tests {
 		testutil.Run(t, test.description, func(t *testutil.T) {
 			tmpDir := t.NewTempDir().
 				Write("kustomization.yaml", test.yaml)
 
+			for path, contents := range test.createFiles {
+				tmpDir.Write(path, contents)
+			}
+
 			k := NewKustomizeDeployer(&runcontext.RunContext{
 				Cfg: &latest.Pipeline{
 					Deploy: latest.DeployConfig{