Set image config created time

Before this was just using whatever created time was set on the base
image config which was incorrect.

Example using the `docker buildx bake runc-jammy-container` command:

Before:

docker image ls | grep runc
runc                                          jammy             8d1d42e074f3   25 minutes ago   228MB

After:

  docker image ls | grep runc
  runc                                          jammy             03c24620c8fa   5 seconds ago    228MB

**Note**: how the created time before was 25mins ago (b/c apparently the base
jammy image was recently updated, I've seen this be 2 weeks) compared to
after its 5 seconds ago.

Signed-off-by: Brian Goff <[email protected]>

frontend/build.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"time"
 
 	"github.com/Azure/dalec"
 	"github.com/containerd/platforms"
@@ -88,6 +89,10 @@ func BuildWithPlatform(ctx context.Context, client gwclient.Client, f PlatformBu
 		targetKey := GetTargetKey(dc)
 
 		ref, cfg, err := f(ctx, client, platform, spec, targetKey)
+		if cfg != nil {
+			now := time.Now()
+			cfg.Created = &now
+		}
 		return ref, cfg, nil, err
 	})
 	if err != nil {

test/azlinux_test.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/Azure/dalec"
 	"github.com/Azure/dalec/frontend/azlinux"
@@ -17,6 +18,7 @@ import (
 	gwclient "github.com/moby/buildkit/frontend/gateway/client"
 	moby_buildkit_v1_frontend "github.com/moby/buildkit/frontend/gateway/pb"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/exp/maps"
 	"gotest.tools/v3/assert"
 )
 
@@ -528,7 +530,16 @@ echo "$BAR" > bar.txt
 			)
 			sr.Evaluate = true
 
-			solveT(ctx, t, gwc, sr)
+			beforeBuild := time.Now()
+			res := solveT(ctx, t, gwc, sr)
+
+			dt, ok := res.Metadata[exptypes.ExporterImageConfigKey]
+			assert.Assert(t, ok, "result metadata should contain an image config: available metadata: %s", strings.Join(maps.Keys(res.Metadata), ", "))
+
+			var cfg dalec.DockerImageSpec
+			assert.Assert(t, json.Unmarshal(dt, &cfg))
+			assert.Check(t, cfg.Created.After(beforeBuild))
+			assert.Check(t, cfg.Created.Before(time.Now()))
 
 			// Make sure the test framework was actually executed by the build target.
 			// This appends a test case so that is expected to fail and as such cause the build to fail.
@@ -542,7 +553,8 @@ echo "$BAR" > bar.txt
 			// update the spec in the solve request
 			withSpec(ctx, t, &spec)(&newSolveRequestConfig{req: &sr})
 
-			if _, err := gwc.Solve(ctx, sr); err == nil {
+			res, err := gwc.Solve(ctx, sr)
+			if err == nil {
 				t.Fatal("expected test spec to run with error but got none")
 			}
 		})