build: add attests flag and sbom/provenance shorthands

Signed-off-by: Justin Chadwell <me@jedevc.com>

commands/build.go

@@ -53,6 +53,7 @@ type buildOptions struct {
 	printFunc      string
 
 	allow         []string
+	attests       []string
 	buildArgs     []string
 	cacheFrom     []string
 	cacheTo       []string
@@ -85,6 +86,9 @@ type commonOptions struct {
 
 	exportPush bool
 	exportLoad bool
+
+	sbom       string
+	provenance string
 }
 
 func runBuild(dockerCli command.Cli, in buildOptions) (err error) {
@@ -212,9 +216,20 @@ func runBuild(dockerCli command.Cli, in buildOptions) (err error) {
 			}
 		}
 	}
-
 	opts.Exports = outputs
 
+	inAttests := append([]string{}, in.attests...)
+	if in.provenance != "" {
+		inAttests = append(inAttests, buildflags.CanonicalizeAttest("provenance", in.provenance))
+	}
+	if in.sbom != "" {
+		inAttests = append(inAttests, buildflags.CanonicalizeAttest("sbom", in.sbom))
+	}
+	opts.Attests, err = buildflags.ParseAttests(inAttests)
+	if err != nil {
+		return err
+	}
+
 	cacheImports, err := buildflags.ParseCacheEntry(in.cacheFrom)
 	if err != nil {
 		return err
@@ -504,6 +519,10 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 
 	flags.Var(options.ulimits, "ulimit", "Ulimit options")
 
+	flags.StringArrayVar(&options.attests, "attest", []string{}, `Attestation parameters (format: "type=sbom,generator=image")`)
+	flags.StringVar(&options.sbom, "sbom", "", `Shorthand for "--attest=type=sbom"`)
+	flags.StringVar(&options.provenance, "provenance", "", `Shortand for "--attest=type=provenance"`)
+
 	if isExperimental() {
 		flags.StringVar(&options.invoke, "invoke", "", "Invoke a command after the build [experimental]")
 	}

docs/reference/buildx_build.md

@@ -17,6 +17,7 @@ Start a build
 | --- | --- | --- | --- |
 | [`--add-host`](https://docs.docker.com/engine/reference/commandline/build/#add-entries-to-container-hosts-file---add-host) | `stringSlice` |  | Add a custom host-to-IP mapping (format: `host:ip`) |
 | [`--allow`](#allow) | `stringSlice` |  | Allow extra privileged entitlement (e.g., `network.host`, `security.insecure`) |
+| `--attest` | `stringArray` |  | Attestation parameters (format: `type=sbom,generator=image`) |
 | [`--build-arg`](#build-arg) | `stringArray` |  | Set build-time variables |
 | [`--build-context`](#build-context) | `stringArray` |  | Additional build contexts (e.g., name=path) |
 | [`--builder`](#builder) | `string` |  | Override the configured builder instance |
@@ -36,9 +37,11 @@ Start a build
 | [`--platform`](#platform) | `stringArray` |  | Set target platform for build |
 | `--print` | `string` |  | Print result of information request (e.g., outline, targets) [experimental] |
 | [`--progress`](#progress) | `string` | `auto` | Set type of progress output (`auto`, `plain`, `tty`). Use plain to show container output |
+| `--provenance` | `string` |  | Shortand for `--attest=type=provenance` |
 | `--pull` |  |  | Always attempt to pull all referenced images |
 | [`--push`](#push) |  |  | Shorthand for `--output=type=registry` |
 | `-q`, `--quiet` |  |  | Suppress the build output and print image ID on success |
+| `--sbom` | `string` |  | Shorthand for `--attest=type=sbom` |
 | [`--secret`](#secret) | `stringArray` |  | Secret to expose to the build (format: `id=mysecret[,src=/local/secret]`) |
 | [`--shm-size`](#shm-size) | `bytes` | `0` | Size of `/dev/shm` |
 | [`--ssh`](#ssh) | `stringArray` |  | SSH agent socket or keys to expose to the build (format: `default\|<id>[=<socket>\|<key>[,<key>]]`) |

util/buildflags/attests.go

@@ -0,0 +1,76 @@
+package buildflags
+
+import (
+	"encoding/csv"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+func CanonicalizeAttest(attestType string, in string) string {
+	if in == "" {
+		return ""
+	}
+	if b, err := strconv.ParseBool(in); err == nil {
+		return fmt.Sprintf("type=%s,enabled=%t", attestType, b)
+	}
+	return fmt.Sprintf("type=%s,%s", attestType, in)
+}
+
+func ParseAttests(in []string) (map[string]*string, error) {
+	out := map[string]*string{}
+	for _, in := range in {
+		in := in
+		attestType, enabled, err := parseAttest(in)
+		if err != nil {
+			return nil, err
+		}
+
+		k := "attest:" + attestType
+		if enabled {
+			out[k] = &in
+		} else {
+			out[k] = nil
+		}
+	}
+	return out, nil
+}
+
+func parseAttest(in string) (string, bool, error) {
+	if in == "" {
+		return "", false, nil
+	}
+
+	csvReader := csv.NewReader(strings.NewReader(in))
+	fields, err := csvReader.Read()
+	if err != nil {
+		return "", false, err
+	}
+
+	attestType := ""
+	enabled := true
+	for _, field := range fields {
+		key, value, ok := strings.Cut(field, "=")
+		if !ok {
+			return "", false, errors.Errorf("invalid value %s", field)
+		}
+		key = strings.TrimSpace(strings.ToLower(key))
+
+		switch key {
+		case "type":
+			attestType = value
+		case "enabled":
+			enabled, err = strconv.ParseBool(value)
+			if err != nil {
+				return "", false, err
+			}
+		}
+	}
+	if attestType == "" {
+		return "", false, errors.Errorf("attestation type not specified")
+	}
+
+	return attestType, enabled, nil
+}