engine: Support plan outputs

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

plan/task/outputdirectory.go

@@ -0,0 +1,43 @@
+package task
+
+import (
+	"context"
+
+	bk "github.com/moby/buildkit/client"
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/plancontext"
+	"go.dagger.io/dagger/solver"
+)
+
+func init() {
+	Register("OutputDirectory", func() Task { return &outputDirectoryTask{} })
+}
+
+type outputDirectoryTask struct {
+}
+
+func (c outputDirectoryTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	contents, err := pctx.FS.FromValue(v.Lookup("contents"))
+	if err != nil {
+		return nil, err
+	}
+
+	dest, err := v.Lookup("dest").String()
+	if err != nil {
+		return nil, err
+	}
+
+	st, err := contents.Result().ToState()
+	if err != nil {
+		return nil, err
+	}
+	_, err = s.Export(ctx, st, nil, bk.ExportEntry{
+		Type:      bk.ExporterLocal,
+		OutputDir: dest,
+	}, pctx.Platform.Get())
+	if err != nil {
+		return nil, err
+	}
+
+	return compiler.NewValue(), nil
+}

stdlib/europa/dagger/engine/plan.cue

@@ -82,7 +82,7 @@ _#inputSecret: {
 }
 
 _#outputDirectory: {
-	@dagger(notimplemented)
+	$dagger: task: _name: "OutputDirectory"
 
 	// Filesystem contents to export
 	// Reference an #FS field produced by an action

tests/plan.bats

@@ -69,3 +69,11 @@ setup() {
 	assert_failure
 	assert_output --partial 'failed: exec: "rtyet": executable file not found'
 }
+
+@test "plan/outputs" {
+    cd "$TESTDIR"/plan/outputs
+
+    rm -f "./out/test"
+    "$DAGGER" --europa up ./outputs.cue
+    assert [ -f "./out/test" ]
+}

tests/plan/outputs/.gitignore

@@ -0,0 +1 @@
+out

tests/plan/outputs/outputs.cue

@@ -0,0 +1,21 @@
+package main
+
+import "alpha.dagger.io/europa/dagger/engine"
+
+engine.#Plan & {
+	actions: {
+		scratch: engine.#Scratch
+
+		data: engine.#WriteFile & {
+			input:    scratch.output
+			path:     "/test"
+			mode:     0o600
+			contents: "foobar"
+		}
+	}
+
+	outputs: directories: test: {
+		contents: actions.data.output
+		dest:     "./out"
+	}
+}