Detect if images are available if we don't have to generate a Package

While building, if we aren't doing a clean build, we scan now to see if
images are available and we skip, in case we don't find a metadata
already.

pkg/compiler/backend/common.go

@@ -0,0 +1,25 @@
+// Copyright © 2020 Ettore Di Giacinto <mudler@gentoo.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package backend
+
+import (
+	"github.com/google/go-containerregistry/pkg/crane"
+)
+
+func imageAvailable(image string) bool {
+	_, err := crane.Digest(image)
+	return err == nil
+}

pkg/compiler/backend/simpledocker.go

@@ -119,6 +119,10 @@ func (*SimpleDocker) ImageExists(imagename string) bool {
 	return true
 }
 
+func (*SimpleDocker) ImageAvailable(imagename string) bool {
+	return imageAvailable(imagename)
+}
+
 func (*SimpleDocker) RemoveImage(opts compiler.CompilerBackendOptions) error {
 	name := opts.ImageName
 	buildarg := []string{"rmi", name}

pkg/compiler/backend/simpledocker_test.go

@@ -124,5 +124,11 @@ RUN echo bar > /test2`))
 
 		})
 
+		It("Detects available images", func() {
+			b := NewSimpleDockerBackend()
+			Expect(b.ImageAvailable("quay.io/mocaccino/extra")).To(BeTrue())
+			Expect(b.ImageAvailable("ubuntu:20.10")).To(BeTrue())
+			Expect(b.ImageAvailable("igjo5ijgo25nho52")).To(BeFalse())
+		})
 	})
 })

pkg/compiler/backend/simpleimg.go

@@ -97,6 +97,10 @@ func (*SimpleImg) CopyImage(src, dst string) error {
 	return nil
 }
 
+func (*SimpleImg) ImageAvailable(imagename string) bool {
+	return imageAvailable(imagename)
+}
+
 func (*SimpleImg) ImageExists(imagename string) bool {
 	// NOOP: not implemented
 	// TODO: Since img doesn't have an inspect command,

pkg/compiler/compiler.go

@@ -507,10 +507,14 @@ func (cs *LuetCompiler) compileWithImage(image, buildertaggedImage, packageImage
 
 	if !cs.Clean {
 		exists := cs.Backend.ImageExists(buildertaggedImage) && cs.Backend.ImageExists(packageImage)
-		if art, err := LoadArtifactFromYaml(p); err == nil && (cs.Options.SkipIfMetadataExists || exists) {
-			Debug("Artifact reloaded. Skipping build")
+		if art, err := LoadArtifactFromYaml(p); err == nil && exists { // If YAML is correctly loaded, and both images exists, no reason to rebuild.
+			Debug("Artifact reloaded from YAML. Skipping build")
 			return art, err
 		}
+		available := cs.Backend.ImageAvailable(buildertaggedImage) && cs.Backend.ImageAvailable(packageImage)
+		if (exists || available) && !generateArtifact {
+			return &PackageArtifact{}, nil
+		}
 	}
 
 	builderOpts, runnerOpts, err := cs.buildPackageImage(image, buildertaggedImage, packageImage, concurrency, keepPermissions, p)

pkg/compiler/interface.go

@@ -52,11 +52,10 @@ type CompilerOptions struct {
 	Clean                    bool
 	KeepImageExport          bool
 
-	OnlyDeps             bool
-	NoDeps               bool
-	SolverOptions        config.LuetSolverOptions
-	SkipIfMetadataExists bool
-	BuildValuesFile      string
+	OnlyDeps        bool
+	NoDeps          bool
+	SolverOptions   config.LuetSolverOptions
+	BuildValuesFile string
 
 	PackageTargetOnly bool
 }
@@ -87,6 +86,7 @@ type CompilerBackend interface {
 	DownloadImage(opts CompilerBackendOptions) error
 
 	Push(opts CompilerBackendOptions) error
+	ImageAvailable(string) bool
 
 	ImageExists(string) bool
 }