build --all-platforms: skip some base "image" platforms

When figuring out which platforms the base images allow us to build
derived images for, screen out any images with non-empty artifactType
values.  Also screen out any which use empty values or the word
"unknown" in the OS and Architecture platform fields, and any
Architecture values that the compiler hasn't heard of.

Signed-off-by: Nalin Dahyabhai <[email protected]>

imagebuildah/build.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	gotypes "go/types"
 	"io"
 	"net/http"
 	"os"
@@ -36,6 +37,7 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/openshift/imagebuilder"
 	"github.com/sirupsen/logrus"
+	"golang.org/x/exp/slices"
 	"golang.org/x/sync/semaphore"
 )
 
@@ -493,6 +495,26 @@ func preprocessContainerfileContents(logger *logrus.Logger, containerfile string
 	return &stdoutBuffer, nil
 }
 
+// platformIsUnknown checks if the platform value indicates that the
+// corresponding index entry is suitable for use as a base image
+func platformIsAcceptable(platform *v1.Platform, logger *logrus.Logger) bool {
+	if platform == nil {
+		logger.Trace("rejecting potential base image with no platform information")
+		return false
+	}
+	if gotypes.SizesFor("gc", platform.Architecture) == nil {
+		// the compiler's never heard of this
+		logger.Tracef("rejecting potential base image architecture %q for which Go has no knowledge of how to do unsafe code", platform.Architecture)
+		return false
+	}
+	if slices.Contains([]string{"", "unknown"}, platform.OS) {
+		// we're hard-wired to reject images with these values
+		logger.Tracef("rejecting potential base image for which the OS value is always-rejected value %q", platform.OS)
+		return false
+	}
+	return true
+}
+
 // platformsForBaseImages resolves the names of base images from the
 // dockerfiles, and if they are all valid references to manifest lists, returns
 // the list of platforms that are supported by all of the base images.
@@ -570,7 +592,10 @@ func platformsForBaseImages(ctx context.Context, logger *logrus.Logger, dockerfi
 		if baseImageIndex == 0 {
 			// populate the list with the first image's normalized platforms
 			for _, instance := range index.Manifests {
-				if instance.Platform == nil {
+				if !platformIsAcceptable(instance.Platform, logger) {
+					continue
+				}
+				if instance.ArtifactType != "" {
 					continue
 				}
 				platform := internalUtil.NormalizePlatform(*instance.Platform)
@@ -581,7 +606,10 @@ func platformsForBaseImages(ctx context.Context, logger *logrus.Logger, dockerfi
 			// prune the list of any normalized platforms this base image doesn't support
 			imagePlatforms := make(map[string]struct{})
 			for _, instance := range index.Manifests {
-				if instance.Platform == nil {
+				if !platformIsAcceptable(instance.Platform, logger) {
+					continue
+				}
+				if instance.ArtifactType != "" {
 					continue
 				}
 				platform := internalUtil.NormalizePlatform(*instance.Platform)

tests/bud/from-base/Containerfile

@@ -0,0 +1,2 @@
+FROM base
+ADD . .

tests/lists.bats

@@ -318,3 +318,30 @@ IMAGE_LIST_S390X_INSTANCE_DIGEST=sha256:882a20ee0df7399a445285361d38b711c299ca09
     # since manifest does not exist in local storage this should exit with `1`
     run_buildah 1 manifest exists test2
 }
+
+@test "manifest-skip-some-base-images-with-all-platforms" {
+    start_registry
+    run_buildah manifest create localhost:"${REGISTRY_PORT}"/base
+    run_buildah manifest add --all localhost:"${REGISTRY_PORT}"/base ${IMAGE_LIST}
+    # get a count of how many "real" base images there are
+    run_buildah manifest inspect localhost:"${REGISTRY_PORT}"/base
+    nbaseplatforms=$(grep '"platform"' <<< "$output" | wc -l)
+    echo $nbaseplatforms base platforms
+    # add some trash that we expect to skip in a --all-platforms build
+    run_buildah build --manifest localhost:"${REGISTRY_PORT}"/base --platform unknown/unknown --no-cache -f $BUDFILES/from-scratch/Containerfile2 $BUDFILES/from-scratch
+    run_buildah build --manifest localhost:"${REGISTRY_PORT}"/base --platform linux/unknown --no-cache -f $BUDFILES/from-scratch/Containerfile2 $BUDFILES/from-scratch
+    run_buildah build --manifest localhost:"${REGISTRY_PORT}"/base --platform unknown/amd64p32 --no-cache -f $BUDFILES/from-scratch/Containerfile2 $BUDFILES/from-scratch
+    # add a known combination of OS/arch that we can be pretty sure wasn't already there
+    run_buildah build --manifest localhost:"${REGISTRY_PORT}"/base --platform linux/amd64p32 --no-cache -f $BUDFILES/from-scratch/Containerfile2 $BUDFILES/from-scratch
+    # push the list to the local registry and clean up our local copy
+    run_buildah manifest push --tls-verify=false --creds testuser:testpassword --all localhost:"${REGISTRY_PORT}"/base
+    run_buildah rmi localhost:"${REGISTRY_PORT}"/base
+    # build a new list based on the valid base images in the list we just pushed
+    run_buildah build --tls-verify=false --creds testuser:testpassword --manifest derived --all-platforms --from localhost:"${REGISTRY_PORT}"/base $BUDFILES/from-base
+    run_buildah manifest inspect derived
+    nderivedplatforms=$(grep '"platform"' <<< "$output" | wc -l)
+    echo $nderivedplatforms derived platforms
+    nexpectedderivedplatforms=$((nbaseplatforms+1))
+    echo expected $nexpectedderivedplatforms derived platforms
+    [[ $nderivedplatforms -eq $nexpectedderivedplatforms ]]
+}