exec: fix platform value in cache key

Use vertex platform instead of the current system one. This shouldn't break any cache unless qemu was used. Even when qemu was used the issue would not cause any cache collisions because the base images for run were scoped by platform, but better to stop using invalid data for cache key calculation.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

solver/llbsolver/ops/exec.go

@@ -10,13 +10,13 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"runtime"
 	"sort"
 	"strings"
 	"sync"
 	"time"
 
 	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/platforms"
 	"github.com/docker/docker/pkg/locker"
 	"github.com/moby/buildkit/cache"
 	"github.com/moby/buildkit/cache/metadata"
@@ -34,6 +34,7 @@ import (
 	utilsystem "github.com/moby/buildkit/util/system"
 	"github.com/moby/buildkit/worker"
 	digest "github.com/opencontainers/go-digest"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/opencontainers/runc/libcontainer/system"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -51,12 +52,13 @@ type execOp struct {
 	md        *metadata.Store
 	exec      executor.Executor
 	w         worker.Worker
+	platform  *pb.Platform
 	numInputs int
 
 	cacheMounts map[string]*cacheRefShare
 }
 
-func NewExecOp(v solver.Vertex, op *pb.Op_Exec, cm cache.Manager, sm *session.Manager, md *metadata.Store, exec executor.Executor, w worker.Worker) (solver.Op, error) {
+func NewExecOp(v solver.Vertex, op *pb.Op_Exec, platform *pb.Platform, cm cache.Manager, sm *session.Manager, md *metadata.Store, exec executor.Executor, w worker.Worker) (solver.Op, error) {
 	return &execOp{
 		op:          op.Exec,
 		cm:          cm,
@@ -65,6 +67,7 @@ func NewExecOp(v solver.Vertex, op *pb.Op_Exec, cm cache.Manager, sm *session.Ma
 		exec:        exec,
 		numInputs:   len(v.Inputs()),
 		w:           w,
+		platform:    platform,
 		cacheMounts: map[string]*cacheRefShare{},
 	}, nil
 }
@@ -98,16 +101,27 @@ func (e *execOp) CacheMap(ctx context.Context, index int) (*solver.CacheMap, boo
 	}
 	op.Meta.ProxyEnv = nil
 
+	p := platforms.DefaultSpec()
+	if e.platform != nil {
+		p = specs.Platform{
+			OS:           e.platform.OS,
+			Architecture: e.platform.Architecture,
+			Variant:      e.platform.Variant,
+		}
+	}
+
 	dt, err := json.Marshal(struct {
-		Type string
-		Exec *pb.ExecOp
-		OS   string
-		Arch string
+		Type    string
+		Exec    *pb.ExecOp
+		OS      string
+		Arch    string
+		Variant string `json:",omitempty"`
 	}{
-		Type: execCacheType,
-		Exec: &op,
-		OS:   runtime.GOOS,
-		Arch: runtime.GOARCH,
+		Type:    execCacheType,
+		Exec:    &op,
+		OS:      p.OS,
+		Arch:    p.Architecture,
+		Variant: p.Variant,
 	})
 	if err != nil {
 		return nil, false, err

worker/base/worker.go

@@ -197,7 +197,7 @@ func (w *Worker) ResolveOp(v solver.Vertex, s frontend.FrontendLLBBridge, sm *se
 		case *pb.Op_Source:
 			return ops.NewSourceOp(v, op, baseOp.Platform, w.SourceManager, sm, w)
 		case *pb.Op_Exec:
-			return ops.NewExecOp(v, op, w.CacheManager, sm, w.MetadataStore, w.Executor, w)
+			return ops.NewExecOp(v, op, baseOp.Platform, w.CacheManager, sm, w.MetadataStore, w.Executor, w)
 		case *pb.Op_Build:
 			return ops.NewBuildOp(v, op, s, w)
 		}