FetchContainer: Inject Docker image metadata into LLB

Fixes #130

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

dagger/pipeline.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/docker/distribution/reference"
 	"github.com/moby/buildkit/client/llb"
 	dockerfilebuilder "github.com/moby/buildkit/frontend/dockerfile/builder"
 	bkgw "github.com/moby/buildkit/frontend/gateway/client"
@@ -484,17 +485,57 @@ func (p *Pipeline) Load(ctx context.Context, op *compiler.Value) error {
 }
 
 func (p *Pipeline) FetchContainer(ctx context.Context, op *compiler.Value) error {
-	ref, err := op.Get("ref").String()
+	rawRef, err := op.Get("ref").String()
 	if err != nil {
 		return err
 	}
-	// FIXME: preserve docker image metadata
-	p.fs = p.fs.Set(
-		llb.Image(ref, llb.WithCustomName(p.vertexNamef("FetchContainer %s", ref))),
+
+	ref, err := reference.ParseNormalizedNamed(rawRef)
+	if err != nil {
+		return 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)
+
+	state := llb.Image(
+		ref.String(),
+		llb.WithCustomName(p.vertexNamef("FetchContainer %s", rawRef)),
 	)
+
+	// Load image metadata and convert to to LLB.
+	// FIXME: metadata MUST be injected back into the gateway result
+	// FIXME: there are unhandled sections of the image config
+	image, err := p.s.ResolveImageConfig(ctx, ref.String(), llb.ResolveImageConfigOpt{
+		LogName: p.vertexNamef("load metadata for %s", ref.String()),
+	})
+	if err != nil {
+		return err
+	}
+
+	for _, env := range image.Config.Env {
+		k, v := parseKeyValue(env)
+		state = state.AddEnv(k, v)
+	}
+	if image.Config.WorkingDir != "" {
+		state = state.Dir(image.Config.WorkingDir)
+	}
+	if image.Config.User != "" {
+		state = state.User(image.Config.User)
+	}
+	p.fs = p.fs.Set(state)
 	return nil
 }
 
+func parseKeyValue(env string) (string, string) {
+	parts := strings.SplitN(env, "=", 2)
+	v := ""
+	if len(parts) > 1 {
+		v = parts[1]
+	}
+
+	return parts[0], v
+}
+
 func (p *Pipeline) FetchGit(ctx context.Context, op *compiler.Value) error {
 	remote, err := op.Get("remote").String()
 	if err != nil {

dagger/solver.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"github.com/moby/buildkit/client/llb"
+	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
 	bkgw "github.com/moby/buildkit/frontend/gateway/client"
 	bkpb "github.com/moby/buildkit/solver/pb"
 	"github.com/opencontainers/go-digest"
@@ -39,6 +40,23 @@ func (s Solver) SessionID() string {
 	return s.c.BuildOpts().SessionID
 }
 
+func (s Solver) ResolveImageConfig(ctx context.Context, ref string, opts llb.ResolveImageConfigOpt) (dockerfile2llb.Image, error) {
+	var image dockerfile2llb.Image
+
+	// Load image metadata and convert to to LLB.
+	// Inspired by https://github.com/moby/buildkit/blob/master/frontend/dockerfile/dockerfile2llb/convert.go
+	// FIXME: this needs to handle platform
+	_, meta, err := s.c.ResolveImageConfig(ctx, ref, opts)
+	if err != nil {
+		return image, err
+	}
+	if err := json.Unmarshal(meta, &image); err != nil {
+		return image, err
+	}
+
+	return image, nil
+}
+
 // Solve will block until the state is solved and returns a Reference.
 func (s Solver) SolveRequest(ctx context.Context, req bkgw.SolveRequest) (bkgw.Reference, error) {
 	// call solve

go.mod

@@ -6,6 +6,7 @@ require (
 	cuelang.org/go v0.3.0-beta.5
 	github.com/KromDaniel/jonson v0.0.0-20180630143114-d2f9c3c389db
 	github.com/containerd/console v1.0.1
+	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/emicklei/proto v1.9.0 // indirect
 	github.com/jaguilar/vt100 v0.0.0-20150826170717-2703a27b14ea
 	github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db

stdlib/go/go.cue

@@ -24,14 +24,8 @@ import (
 		dagger.#Exec & {
 			"args": ["go"] + args
 
-			env: env
-			env: CGO_ENABLED: "0"
-			// FIXME: this should come from the golang image.
-			// https://github.com/dagger/dagger/issues/130
-			env: {
-				PATH:   "/go/bin:/usr/local/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
-				GOPATH: "/go"
-			}
+			"env": env
+			"env": CGO_ENABLED: "0"
 
 			dir: "/src"
 			mount: "/src": from: source