use layer cache when building images

to more closely mimic docker default behavior, the --layers
cli option is set to true by default for podman.  the buildah
environment variable of BUILDAH_LAYERS is still honored and will
override the command line input.

this should be considered in place of PR #1383.

Many thanks for Scott McCarty for inspiring this welcome change.

Signed-off-by: baude <bbaude@redhat.com>

Closes: #1422
Approved by: rhatdan

1 files changed, 17 insertions, 4 deletions

diff --git a/vendor/github.com/projectatomic/buildah/pkg/cli/common.go b/vendor/github.com/projectatomic/buildah/pkg/cli/common.go
index 0d035f471..a438daf6a 100644
--- a/vendor/github.com/projectatomic/buildah/pkg/cli/common.go
+++ b/vendor/github.com/projectatomic/buildah/pkg/cli/common.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
 	"github.com/projectatomic/buildah"
 	"github.com/projectatomic/buildah/util"
 	"github.com/urfave/cli"
@@ -68,6 +69,13 @@ var (
 		},
 	}
 
+	LayerFlags = []cli.Flag{
+		cli.BoolFlag{
+			Name:  "layers",
+			Usage: fmt.Sprintf("cache intermediate layers during build. Use BUILDAH_LAYERS environment variable to override. (default %t)", UseLayers()),
+		},
+	}
+
 	BudFlags = []cli.Flag{
 		cli.StringSliceFlag{
 			Name:  "annotation",
@@ -130,10 +138,6 @@ var (
 			Usage: "Set metadata for an image (default [])",
 		},
 		cli.BoolFlag{
-			Name:  "layers",
-			Usage: fmt.Sprintf("cache intermediate layers during build. Use BUILDAH_LAYERS environment variable to override. (default %t)", UseLayers()),
-		},
-		cli.BoolFlag{
 			Name:  "no-cache",
 			Usage: "Do not use existing cached images for the container build. Build from the start with a new set of cached layers.",
 		},
@@ -280,3 +284,12 @@ func DefaultIsolation() string {
 	}
 	return buildah.OCI
 }
+
+func VerifyFlagsArgsOrder(args []string) error {
+	for _, arg := range args {
+		if strings.HasPrefix(arg, "-") {
+			return errors.Errorf("No options (%s) can be specified after the image or container name", arg)
+		}
+	}
+	return nil
+}