config: support the variant field

cmd/buildah/config.go

@@ -43,6 +43,7 @@ type configResults struct {
 	shell                  string
 	stopSignal             string
 	user                   string
+	variant                string
 	volume                 []string
 	workingDir             string
 }
@@ -91,6 +92,7 @@ func init() {
 	flags.StringVar(&opts.shell, "shell", "", "add `shell` to run in containers")
 	flags.StringVar(&opts.stopSignal, "stop-signal", "", "set `stop signal` for containers based on image")
 	flags.StringVarP(&opts.user, "user", "u", "", "set default `user` to run inside containers based on image")
+	flags.StringVar(&opts.variant, "variant", "", "set architecture `variant` of the target image")
 	flags.StringSliceVarP(&opts.volume, "volume", "v", []string{}, "add default `volume` path to be created for containers based on image (default [])")
 	flags.StringVar(&opts.workingDir, "workingdir", "", "set working `directory` for containers based on image")
 
@@ -169,6 +171,9 @@ func updateConfig(builder *buildah.Builder, c *cobra.Command, iopts configResult
 	if c.Flag("arch").Changed {
 		builder.SetArchitecture(iopts.arch)
 	}
+	if c.Flag("variant").Changed {
+		builder.SetVariant(iopts.variant)
+	}
 	if c.Flag("os").Changed {
 		builder.SetOS(iopts.os)
 	}

config.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/containerd/containerd/platforms"
 	"github.com/containers/buildah/define"
 	"github.com/containers/buildah/docker"
 	"github.com/containers/image/v5/manifest"
@@ -133,6 +134,10 @@ func (b *Builder) fixupConfig(sys *types.SystemContext) {
 		} else {
 			b.SetArchitecture(runtime.GOARCH)
 		}
+		// in case the arch string we started with was shorthand for a known arch+variant pair, normalize it
+		ps := platforms.Normalize(ociv1.Platform{OS: b.OS(), Architecture: b.Architecture(), Variant: b.Variant()})
+		b.SetArchitecture(ps.Architecture)
+		b.SetVariant(ps.Variant)
 	}
 	if b.Format == define.Dockerv2ImageManifest && b.Hostname() == "" {
 		b.SetHostname(stringid.TruncateID(stringid.GenerateRandomID()))
@@ -212,6 +217,21 @@ func (b *Builder) SetArchitecture(arch string) {
 	b.Docker.Architecture = arch
 }
 
+// Variant returns a name of the architecture variant on which the container,
+// or a container built using an image built from this container, is intended
+// to be run.
+func (b *Builder) Variant() string {
+	return b.OCIv1.Variant
+}
+
+// SetVariant sets the name of the architecture variant on which the container,
+// or a container built using an image built from this container, is intended
+// to be run.
+func (b *Builder) SetVariant(variant string) {
+	b.Docker.Variant = variant
+	b.OCIv1.Variant = variant
+}
+
 // Maintainer returns contact information for the person who built the image.
 func (b *Builder) Maintainer() string {
 	return b.OCIv1.Author

contrib/completions/bash/buildah

@@ -301,6 +301,7 @@ return 1
        --stop-signal
        --user
        -u
+       --variant
        --volume
        -v
        --workingdir
@@ -435,7 +436,6 @@ return 1
      --os
      --pid
      --platform
-     --platforms
      --runtime
      --runtime-flag
      --security-opt
@@ -451,6 +451,7 @@ return 1
      --userns-uid-map-user
      --userns-gid-map-group
      --uts
+     --variant
      --volume
      -v
   "
@@ -1099,6 +1100,7 @@ esac
 
      local options_with_args="
      --add-host
+     --arch
      --authfile
      --cap-add
      --cap-drop
@@ -1123,7 +1125,9 @@ esac
      --name
      --net
      --network
+     --os
      --pid
+     --platform
      --security-opt
      --shm-size
      --ulimit
@@ -1133,6 +1137,7 @@ esac
      --userns-uid-map-user
      --userns-gid-map-group
      --uts
+     --variant
      --volume
   "
 

docker/types.go

@@ -151,6 +151,8 @@ type V1Image struct {
 	Config *Config `json:"config,omitempty"`
 	// Architecture is the hardware that the image is build and runs on
 	Architecture string `json:"architecture,omitempty"`
+	// Variant is a variant of the CPU that the image is built and runs on
+	Variant string `json:"variant,omitempty"`
 	// OS is the operating system used to build and run the image
 	OS string `json:"os,omitempty"`
 	// Size is the total size of the image including all layers it is composed of

docs/buildah-config.1.md

@@ -186,6 +186,13 @@ or UID, optionally followed by a group name or GID, separated by a colon (':').
 If names are used, the container should include entries for those names in its
 */etc/passwd* and */etc/group* files.
 
+**--variant** *variant*
+
+Set the target architecture *variant* for any images which will be built using
+the specified container.  By default, if the container was based on an image,
+that image's target architecture and variant information is kept, otherwise the
+host's architecture and variant are recorded.
+
 **--volume**, **-v** *volume*
 
 Add a location in the directory tree which should be marked as a *volume* in any images which will be built using the specified container. Can be used multiple times. If *volume* has a trailing `-`, and is already set, then the *volume* is removed from the config.

info.go

@@ -11,10 +11,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/containerd/containerd/platforms"
 	"github.com/containers/buildah/util"
 	"github.com/containers/storage"
 	"github.com/containers/storage/pkg/system"
 	"github.com/containers/storage/pkg/unshare"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
@@ -43,8 +45,10 @@ func Info(store storage.Store) ([]InfoData, error) {
 
 func hostInfo() map[string]interface{} {
 	info := map[string]interface{}{}
-	info["os"] = runtime.GOOS
-	info["arch"] = runtime.GOARCH
+	ps := platforms.Normalize(v1.Platform{OS: runtime.GOOS, Architecture: runtime.GOARCH})
+	info["os"] = ps.OS
+	info["arch"] = ps.Architecture
+	info["variant"] = ps.Variant
 	info["cpus"] = runtime.NumCPU()
 	info["rootless"] = unshare.IsRootless()
 

tests/config.bats

@@ -198,6 +198,7 @@ function check_matrix() {
    --created-by COINCIDENCE \
    --arch amd64 \
    --os linux \
+   --variant abc \
    --user likes:things \
    --port 12345 \
    --env VARIABLE=VALUE1,VALUE2 \
@@ -228,6 +229,7 @@ function check_matrix() {
   check_matrix 'Author'       'TESTAUTHOR'
   check_matrix 'Architecture' 'amd64'
   check_matrix 'OS'           'linux'
+  check_matrix 'Variant'      'abc'
 
   run_buildah inspect --format '{{.ImageCreatedBy}}' $cid
   expect_output "COINCIDENCE"

tests/inspect.bats

@@ -113,3 +113,14 @@ load helpers
 	run_buildah inspect --format "{{.Docker}}" alpine
         expect_output --substring '\{'
 }
+
+@test "inspect-format-docker-variant" {
+	# github.com/containerd/containerd/platforms.Normalize() converts Arch:"armhf" to Arch:"arm"+Variant:"v7",
+	# so check that platform normalization happens at least for that one
+	run_buildah from --quiet --pull=false --signature-policy ${TESTSDIR}/policy.json --arch=armhf scratch
+	cid=$output
+	run_buildah inspect --format "{{.Docker.Architecture}}" $cid
+	[[ "$output" == "arm" ]]
+	run_buildah inspect --format "{{.Docker.Variant}}" $cid
+	[[ "$output" == "v7" ]]
+}