engine.#Pull implementation

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

plan/task/pull.go

@@ -0,0 +1,79 @@
+package task
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"cuelang.org/go/cue"
+	"github.com/docker/distribution/reference"
+	"github.com/moby/buildkit/client/llb"
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/plancontext"
+	"go.dagger.io/dagger/solver"
+)
+
+func init() {
+	Register("Pull", func() Task { return &pullTask{} })
+}
+
+type pullTask struct {
+}
+
+func (c *pullTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	// FIXME: handle auth
+	rawRef, err := v.Lookup("source").String()
+	if err != nil {
+		return nil, err
+	}
+
+	ref, err := reference.ParseNormalizedNamed(rawRef)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse ref %s: %w", rawRef, err)
+	}
+	// Add the default tag "latest" to a reference if it only has a repo name.
+	ref = reference.TagNameOnly(ref)
+
+	st := llb.Image(
+		ref.String(),
+		withCustomName(v, "FetchContainer %s", rawRef),
+	)
+
+	// Load image metadata and convert to to LLB.
+	platform := pctx.Platform.Get()
+	image, digest, err := s.ResolveImageConfig(ctx, ref.String(), llb.ResolveImageConfigOpt{
+		LogName:  vertexNamef(v, "load metadata for %s", ref.String()),
+		Platform: &platform,
+	})
+	if err != nil {
+		return nil, err
+	}
+	imageJSON, err := json.Marshal(image)
+	if err != nil {
+		return nil, err
+	}
+	// Apply Image Config on top of LLB instructions
+	st, err = st.WithImageConfig(imageJSON)
+	if err != nil {
+		return nil, err
+	}
+
+	result, err := s.Solve(ctx, st, pctx.Platform.Get())
+	if err != nil {
+		return nil, err
+	}
+	fs := pctx.FS.New(result)
+
+	out := compiler.NewValue()
+	if err := out.FillPath(cue.ParsePath("output"), fs.MarshalCUE()); err != nil {
+		return nil, err
+	}
+	if err := out.FillPath(cue.ParsePath("digest"), digest.String()); err != nil {
+		return nil, err
+	}
+	if err := out.FillPath(cue.ParsePath("config"), image.Config); err != nil {
+		return nil, err
+	}
+
+	return out, nil
+}

plan/task/util.go

@@ -7,8 +7,12 @@ import (
 	"go.dagger.io/dagger/compiler"
 )
 
-func withCustomName(v *compiler.Value, format string, a ...interface{}) llb.ConstraintsOpt {
+func vertexNamef(v *compiler.Value, format string, a ...interface{}) string {
 	prefix := fmt.Sprintf("@%s@", v.Path().String())
 	name := fmt.Sprintf(format, a...)
-	return llb.WithCustomName(prefix + " " + name)
+	return prefix + " " + name
+}
+
+func withCustomName(v *compiler.Value, format string, a ...interface{}) llb.ConstraintsOpt {
+	return llb.WithCustomName(vertexNamef(v, format, a...))
 }