Use correct run image label name for distro name/version

The spec and docs say that the run image distro and version should be
specified via the Docker image labels `io.buildpacks.base.distro.name`
and `io.buildpacks.base.distro.version`.

See:
https://github.com/buildpacks/spec/blob/buildpack/v0.10/platform.md#target-data

However, until now the lifecycle implementation was checking for
label names that were missing the `.base` substring from the name.

This causes distro name/version `buildpack.toml` target detection
to fail, as well as the env vars `CNB_TARGET_DISTRO_NAME` and
`CNB_TARGET_DISTRO_VERSION` not to be set correctly in the
buildpack environment.

Fixes buildpacks#1324.

phase/analyzer_test.go

@@ -490,8 +490,8 @@ func testAnalyzer(platformAPI string) func(t *testing.T, when spec.G, it spec.S)
 					h.AssertNil(t, previousImage.SetOSVersion("95"))
 					h.AssertNil(t, previousImage.SetArchitecture("Pentium"))
 					h.AssertNil(t, previousImage.SetVariant("MMX"))
-					h.AssertNil(t, previousImage.SetLabel("io.buildpacks.distro.name", "moobuntu"))
-					h.AssertNil(t, previousImage.SetLabel("io.buildpacks.distro.version", "Helpful Holstein"))
+					h.AssertNil(t, previousImage.SetLabel("io.buildpacks.base.distro.name", "moobuntu"))
+					h.AssertNil(t, previousImage.SetLabel("io.buildpacks.base.distro.version", "Helpful Holstein"))
 
 					md, err := analyzer.Analyze()
 					h.AssertNil(t, err)

phase/rebaser_test.go

@@ -771,17 +771,17 @@ func testRebaser(t *testing.T, when spec.G, it spec.S) {
 								h.AssertError(t, err, `unable to satisfy target os/arch constraints; new run image: {"os":"linux","arch":"amd64","arch-variant":"variant2"}, old run image: {"os":"linux","arch":"amd64","arch-variant":"variant1"}`)
 							})
 
-							it("errors and prevents the rebase from taking place when the io.buildpacks.distro.name are different", func() {
-								h.AssertNil(t, fakeAppImage.SetLabel("io.buildpacks.distro.name", "distro1"))
-								h.AssertNil(t, fakeNewBaseImage.SetLabel("io.buildpacks.distro.name", "distro2"))
+							it("errors and prevents the rebase from taking place when the io.buildpacks.base.distro.name are different", func() {
+								h.AssertNil(t, fakeAppImage.SetLabel("io.buildpacks.base.distro.name", "distro1"))
+								h.AssertNil(t, fakeNewBaseImage.SetLabel("io.buildpacks.base.distro.name", "distro2"))
 
 								_, err := rebaser.Rebase(fakeAppImage, fakeNewBaseImage, fakeAppImage.Name(), additionalNames)
 								h.AssertError(t, err, `unable to satisfy target os/arch constraints; new run image: {"os":"linux","arch":"amd64","distro":{"name":"distro2","version":""}}, old run image: {"os":"linux","arch":"amd64","distro":{"name":"distro1","version":""}}`)
 							})
 
-							it("errors and prevents the rebase from taking place when the io.buildpacks.distro.version are different", func() {
-								h.AssertNil(t, fakeAppImage.SetLabel("io.buildpacks.distro.version", "version1"))
-								h.AssertNil(t, fakeNewBaseImage.SetLabel("io.buildpacks.distro.version", "version2"))
+							it("errors and prevents the rebase from taking place when the io.buildpacks.base.distro.version are different", func() {
+								h.AssertNil(t, fakeAppImage.SetLabel("io.buildpacks.base.distro.version", "version1"))
+								h.AssertNil(t, fakeNewBaseImage.SetLabel("io.buildpacks.base.distro.version", "version2"))
 
 								_, err := rebaser.Rebase(fakeAppImage, fakeNewBaseImage, fakeAppImage.Name(), additionalNames)
 								h.AssertError(t, err, `unable to satisfy target os/arch constraints; new run image: {"os":"linux","arch":"amd64","distro":{"name":"","version":"version2"}}, old run image: {"os":"linux","arch":"amd64","distro":{"name":"","version":"version1"}}`)

platform/run_image.go

@@ -17,9 +17,9 @@ const (
 	// TargetLabel is the label containing the target ID.
 	TargetLabel = "io.buildpacks.base.id"
 	// OSDistroNameLabel is the label containing the OS distribution name.
-	OSDistroNameLabel = "io.buildpacks.distro.name"
+	OSDistroNameLabel = "io.buildpacks.base.distro.name"
 	// OSDistroVersionLabel is the label containing the OS distribution version.
-	OSDistroVersionLabel = "io.buildpacks.distro.version"
+	OSDistroVersionLabel = "io.buildpacks.base.distro.version"
 )
 
 func BestRunImageMirrorFor(targetRegistry string, runImageMD files.RunImageForExport, checkReadAccess CheckReadAccess) (string, error) {