dagger.#FS support

- Implement dagger.#FS support
- Migrate `context.imports` to dagger.#FS
- Backward compat: dagger.#FS can be passed in lieu of a
  dagger.#Artifact
- For instance, an import (`dagger.#FS`) can be passed to the current
  `yarn.#Package` implementation

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

plan/task/import.go

@@ -2,9 +2,9 @@ package task
 
 import (
 	"context"
-	"fmt"
-	"os"
 
+	"cuelang.org/go/cue"
+	"github.com/moby/buildkit/client/llb"
 	"go.dagger.io/dagger/compiler"
 	"go.dagger.io/dagger/plancontext"
 	"go.dagger.io/dagger/solver"
@@ -17,21 +17,64 @@ func init() {
 type importTask struct {
 }
 
-func (c importTask) Run(ctx context.Context, pctx *plancontext.Context, _ solver.Solver, v *compiler.Value) (*compiler.Value, error) {
-	var dir *plancontext.Directory
+func (c importTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	var dir struct {
+		Path    string
+		Include []string
+		Exclude []string
+	}
 
 	if err := v.Decode(&dir); err != nil {
 		return nil, err
 	}
 
-	// Check that directory exists
-	if _, err := os.Stat(dir.Path); os.IsNotExist(err) {
-		return nil, fmt.Errorf("%q dir doesn't exist", dir.Path)
+	opts := []llb.LocalOption{
+		withCustomName(v, "Local %s", dir.Path),
+		// Without hint, multiple `llb.Local` operations on the
+		// same path get a different digest.
+		llb.SessionID(s.SessionID()),
+		llb.SharedKeyHint(dir.Path),
 	}
 
-	id := pctx.Directories.Register(dir)
-	return compiler.Compile("", fmt.Sprintf(
-		`fs: #up: [{do: "local", id: %q}]`,
-		id,
-	))
+	if len(dir.Include) > 0 {
+		opts = append(opts, llb.IncludePatterns(dir.Include))
+	}
+
+	// Excludes .dagger directory by default
+	excludePatterns := []string{"**/.dagger/"}
+	if len(dir.Exclude) > 0 {
+		excludePatterns = dir.Exclude
+	}
+	opts = append(opts, llb.ExcludePatterns(excludePatterns))
+
+	// FIXME: Remove the `Copy` and use `Local` directly.
+	//
+	// Copy'ing is a costly operation which should be unnecessary.
+	// However, using llb.Local directly breaks caching sometimes for unknown reasons.
+	st := llb.Scratch().File(
+		llb.Copy(
+			llb.Local(
+				dir.Path,
+				opts...,
+			),
+			"/",
+			"/",
+		),
+		withCustomName(v, "Local %s [copy]", dir.Path),
+	)
+
+	result, err := s.Solve(ctx, st, pctx.Platform.Get())
+	if err != nil {
+		return nil, err
+	}
+
+	id := pctx.FS.Register(&plancontext.FS{
+		Result: result,
+	})
+
+	return compiler.NewValueWithContent(id,
+		cue.Str("fs"),
+		cue.Hid("_fs", "alpha.dagger.io/dagger"),
+		cue.Str("id"),
+	)
 }

plan/task/secretenv.go

@@ -40,9 +40,8 @@ func (c secretEnvTask) Run(ctx context.Context, pctx *plancontext.Context, _ sol
 		PlainText: env,
 	})
 
-	out := compiler.NewValue()
-	if err := out.FillPath(cue.ParsePath("contents.id"), id); err != nil {
-		return nil, err
-	}
-	return out, nil
+	return compiler.NewValueWithContent(id,
+		cue.Str("contents"),
+		cue.Str("id"),
+	)
 }

plan/task/secretfile.go

@@ -39,9 +39,8 @@ func (c secretFileTask) Run(ctx context.Context, pctx *plancontext.Context, _ so
 		PlainText: string(data),
 	})
 
-	out := compiler.NewValue()
-	if err := out.FillPath(cue.ParsePath("contents.id"), id); err != nil {
-		return nil, err
-	}
-	return out, nil
+	return compiler.NewValueWithContent(id,
+		cue.Str("contents"),
+		cue.Str("id"),
+	)
 }

plan/task/util.go

@@ -0,0 +1,14 @@
+package task
+
+import (
+	"fmt"
+
+	"github.com/moby/buildkit/client/llb"
+	"go.dagger.io/dagger/compiler"
+)
+
+func withCustomName(v *compiler.Value, format string, a ...interface{}) llb.ConstraintsOpt {
+	prefix := fmt.Sprintf("@%s@", v.Path().String())
+	name := fmt.Sprintf(format, a...)
+	return llb.WithCustomName(prefix + " " + name)
+}