disable push step if no registry was configured

docs/getting-started.md

@@ -12,10 +12,18 @@ $ cd examples/example-python
 
 ## Draft Setup
 
-Before we start, we need to set a default registry where we will be pushing all of our images to. In this case, we want to push images to our custom registry sitting at `myregistry.com` so the image will be pushed and pulled from `myregistry.com/example-python`, so to do that, we run
+For minikube environments, the recommended way to get started is by talking to minikube's Docker daemon. To do this, we run
 
+```shell
+$ eval $(minikube docker-env)
 ```
-draft config set registry myregistry.com
+
+Draft will pick up on this and build Docker images using Minikube's in-cluster Docker daemon, making the build process quick and speedy.
+
+If we're using a cloud-provided solution like [Azure Container Service](https://azure.microsoft.com/en-us/services/container-service/), we need to configure a registry where we will be pushing all of our images to, so all nodes in the Kubernetes cluster can pull the images we build using Draft. for this example, we want to push images to our registry sitting at `myregistry.com`, and pull those images down to the Kubernetes cluster from that same registry. To do that, we run
+
+```shell
+$ draft config set registry myregistry.com
 ```
 
 This command tells Draft to push images to this Docker registry, and for Kubernetes to pull images from this Docker registry.

pkg/builder/builder.go

@@ -3,7 +3,6 @@ package builder
 import (
 	"bytes"
 	"crypto/sha256"
-	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -300,9 +299,11 @@ func (b *Builder) Up(ctx context.Context, bctx *Context) <-chan *Summary {
 			fmt.Printf("buildApp: buildImg error: %v\n", err)
 			return
 		}
-		if err := b.pushImg(ctx, app, ch); err != nil {
-			fmt.Printf("buildApp: pushImg error: %v\n", err)
-			return
+		if app.ctx.Env.Registry != "" {
+			if err := b.pushImg(ctx, app, ch); err != nil {
+				fmt.Printf("buildApp: pushImg error: %v\n", err)
+				return
+			}
 		}
 		if err := b.release(ctx, app, ch); err != nil {
 			fmt.Printf("buildApp: release error: %v\n", err)
@@ -347,10 +348,6 @@ func (b *Builder) buildImg(ctx context.Context, app *AppContext, out chan<- *Sum
 	msgc := make(chan string)
 	errc := make(chan error)
 	go func() {
-		if app.ctx.Env.Registry == "" {
-			errc <- errors.New("No registry was configured")
-			return
-		}
 		buildopts := types.ImageBuildOptions{Tags: []string{app.img}}
 		resp, err := b.DockerClient.Client().ImageBuild(ctx, app.buf, buildopts)
 		if err != nil {