add skaffold build --push flag

What is the problem being solved?
Fixes GoogleContainerTools#5667, adding --push flag to skaffold build.  This --push flag overrides any skaffold.yaml pushImages configuration for a build allowing easier artifact pushing after local dev without having to modify yaml configuration.

Why is this the best approach?
This approach follows the style and convention for adding a flag that has been used prior for adding a flag used by one command, similar to #GoogleContainerTools#4039. Additionally this approach does not change the skaffold build default push behaviour to be false, instead only taking precendence when the --push flag is set true which is the intended use case.

What other approaches did you consider?
N/A

What side effects will this approach have?
The addition of this single flag should not have side effects on skaffold functionally outside of --push, the default behavior for skaffold build will be preserved w/o --push specified.

What future work remains to be done?
N/A

Author: aaron-prindle

cmd/skaffold/app/cmd/build.go

@@ -55,6 +55,7 @@ func NewCmdBuild() *cobra.Command {
 			{Value: buildFormatFlag, Name: "output", Shorthand: "o", DefValue: defaultBuildFormatTemplate, Usage: "Used in conjunction with --quiet flag. " + buildFormatFlag.Usage()},
 			{Value: &buildOutputFlag, Name: "file-output", DefValue: "", Usage: "Filename to write build images to"},
 			{Value: &opts.DryRun, Name: "dry-run", DefValue: false, Usage: "Don't build images, just compute the tag for each artifact.", IsEnum: true},
+			{Value: &opts.PushImages, Name: "push", DefValue: false, Usage: "Push the built images to the specified image repository.", IsEnum: true},
 		}).
 		WithHouseKeepingMessages().
 		NoArgs(doBuild)

docs/content/en/docs/references/cli/_index.md

@@ -179,6 +179,9 @@ Examples:
   # Print the final image names
   skaffold build -q --dry-run
 
+  # Push the final images regardless the skaffold.yaml configuration
+  skaffold build --push
+
 Options:
   -b, --build-image=[]: Only build artifacts with image names that contain the given substring. Default is to build sources for all artifacts
       --cache-artifacts=true: Set to false to disable default caching of artifacts
@@ -477,6 +480,7 @@ Env vars:
 * `SKAFFOLD_PORT_FORWARD` (same as `--port-forward`)
 * `SKAFFOLD_PROFILE` (same as `--profile`)
 * `SKAFFOLD_PROFILE_AUTO_ACTIVATION` (same as `--profile-auto-activation`)
+* `SKAFFOLD_PUSH` (same as `--push`)
 * `SKAFFOLD_REMOTE_CACHE_DIR` (same as `--remote-cache-dir`)
 * `SKAFFOLD_RPC_HTTP_PORT` (same as `--rpc-http-port`)
 * `SKAFFOLD_RPC_PORT` (same as `--rpc-port`)

pkg/skaffold/config/options.go

@@ -92,6 +92,7 @@ type SkaffoldOptions struct {
 	MinikubeProfile  string
 	RepoCacheDir     string
 	WaitForDeletions WaitForDeletions
+	PushImages       bool
 }
 
 type RunMode string

pkg/skaffold/runner/build_deploy_test.go

@@ -171,6 +171,27 @@ func TestBuildDryRun(t *testing.T) {
 	})
 }
 
+func TestBuildPushFlag(t *testing.T) {
+	testutil.Run(t, "", func(t *testutil.T) {
+		testBench := &TestBench{}
+		artifacts := []*latest.Artifact{
+			{ImageName: "img1"},
+			{ImageName: "img2"},
+		}
+		runner := createRunner(t, testBench, nil, artifacts, nil)
+		runner.runCtx.Opts.PushImages = true
+		// TODO(aprindle) find out how to set skaffold.yaml values, specifically
+		// build.local.push: false programatically in a test
+
+		_, err := runner.Build(context.Background(), ioutil.Discard, artifacts)
+
+		t.CheckNoError(err)
+
+		// TODO(aprindle) find out how/where to check that the --push overrides the
+		// build.local.push: false setting
+	})
+}
+
 func TestDigestSources(t *testing.T) {
 	artifacts := []*latest.Artifact{
 		{ImageName: "img1"},

pkg/skaffold/runner/new.go

@@ -186,7 +186,10 @@ func isImageLocal(runCtx *runcontext.RunContext, imageName string) (bool, error)
 
 	cl := runCtx.GetCluster()
 	var pushImages bool
-	if pipeline.Build.LocalBuild.Push == nil {
+	if runCtx.Opts.PushImages {
+		logrus.Debugf("push value set via skaffold build --push flag")
+		pushImages = runCtx.Opts.PushImages
+	} else if pipeline.Build.LocalBuild.Push == nil {
 		pushImages = cl.PushImages
 		logrus.Debugf("push value not present, defaulting to %t because cluster.PushImages is %t", pushImages, cl.PushImages)
 	} else {