build: add experimental support for print flag

Print flag can be used to make additional information
requests about the build and print their results.

Currently Dockerfile supports: outline, targets, subrequests.describe

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

vendor/github.com/moby/buildkit/client/diskusage.go

@@ -10,18 +10,18 @@ import (
 )
 
 type UsageInfo struct {
-	ID      string
-	Mutable bool
-	InUse   bool
-	Size    int64
+	ID      string `json:"id"`
+	Mutable bool   `json:"mutable"`
+	InUse   bool   `json:"inUse"`
+	Size    int64  `json:"size"`
 
-	CreatedAt   time.Time
-	LastUsedAt  *time.Time
-	UsageCount  int
-	Parents     []string
-	Description string
-	RecordType  UsageRecordType
-	Shared      bool
+	CreatedAt   time.Time       `json:"createdAt"`
+	LastUsedAt  *time.Time      `json:"lastUsedAt"`
+	UsageCount  int             `json:"usageCount"`
+	Parents     []string        `json:"parents"`
+	Description string          `json:"description"`
+	RecordType  UsageRecordType `json:"recordType"`
+	Shared      bool            `json:"shared"`
 }
 
 func (c *Client) DiskUsage(ctx context.Context, opts ...DiskUsageOption) ([]*UsageInfo, error) {

vendor/github.com/moby/buildkit/client/info.go

@@ -9,13 +9,13 @@ import (
 )
 
 type Info struct {
-	BuildkitVersion BuildkitVersion
+	BuildkitVersion BuildkitVersion `json:"buildkitVersion"`
 }
 
 type BuildkitVersion struct {
-	Package  string
-	Version  string
-	Revision string
+	Package  string `json:"package"`
+	Version  string `json:"version"`
+	Revision string `json:"revision"`
 }
 
 func (c *Client) Info(ctx context.Context) (*Info, error) {

vendor/github.com/moby/buildkit/client/llb/sourcemap.go

@@ -61,7 +61,7 @@ func (smc *sourceMapCollector) Add(dgst digest.Digest, ls []*SourceLocation) {
 		}
 		smc.index[l.SourceMap] = idx
 	}
-	smc.locations[dgst] = ls
+	smc.locations[dgst] = append(smc.locations[dgst], ls...)
 }
 
 func (smc *sourceMapCollector) Marshal(ctx context.Context, co ...ConstraintsOpt) (*pb.Source, error) {

vendor/github.com/moby/buildkit/client/llb/state.go

@@ -199,10 +199,10 @@ func marshal(ctx context.Context, v Vertex, def *Definition, s *sourceMapCollect
 	if opMeta != nil {
 		def.Metadata[dgst] = mergeMetadata(def.Metadata[dgst], *opMeta)
 	}
+	s.Add(dgst, sls)
 	if _, ok := cache[dgst]; ok {
 		return def, nil
 	}
-	s.Add(dgst, sls)
 	def.Def = append(def.Def, dt)
 	cache[dgst] = struct{}{}
 	return def, nil

vendor/github.com/moby/buildkit/client/solve.go

@@ -209,8 +209,10 @@ func (c *Client) solve(ctx context.Context, def *llb.Definition, runGateway runG
 				<-time.After(3 * time.Second)
 				cancelStatus()
 			}()
-			bklog.G(ctx).Debugf("stopping session")
-			s.Close()
+			if !opt.SessionPreInitialized {
+				bklog.G(ctx).Debugf("stopping session")
+				s.Close()
+			}
 		}()
 		var pbd *pb.Definition
 		if def != nil {