engine.#WriteFile

Signed-off-by: Joel Longtine <joel@dagger.io>

plan/task/writefile.go

@@ -0,0 +1,90 @@
+package task
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+
+	"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"
+)
+
+func init() {
+	Register("WriteFile", func() Task { return &writeFileTask{} })
+}
+
+type writeFileTask struct {
+}
+
+func (t *writeFileTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	var contents []byte
+	var err error
+
+	path, err := v.Lookup("path").String()
+	if err != nil {
+		return nil, err
+	}
+
+	switch kind := v.Lookup("contents").Kind(); kind {
+	// TODO: support bytes?
+	// case cue.BytesKind:
+	// 	contents, err = v.Lookup("contents").Bytes()
+	case cue.StringKind:
+		var str string
+		str, err = v.Lookup("contents").String()
+		if err == nil {
+			contents = []byte(str)
+		}
+	case cue.BottomKind:
+		err = fmt.Errorf("%s: WriteFile contents is not set", path)
+	default:
+		err = fmt.Errorf("%s: unhandled data type in WriteFile: %s", path, kind)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	mode, err := v.Lookup("mode").Int64()
+
+	// err = fmt.Errorf("%s: unhandled data type in WriteFile: %w", path, err)
+	if err != nil {
+		return nil, err
+	}
+
+	input, err := pctx.FS.FromValue(v.Lookup("input"))
+
+	if err != nil {
+		return nil, err
+	}
+
+	inputState, err := input.Result().ToState()
+
+	if err != nil {
+		return nil, err
+	}
+
+	outputState := inputState.File(
+		llb.Mkfile(path, fs.FileMode(mode), contents),
+		withCustomName(v, "WriteFile %s", path),
+	)
+
+	result, err := s.Solve(ctx, outputState, pctx.Platform.Get())
+
+	if err != nil {
+		return nil, err
+	}
+
+	fs := pctx.FS.New(result)
+
+	output := compiler.NewValue()
+
+	if err := output.FillPath(cue.ParsePath("output"), fs.MarshalCUE()); err != nil {
+		return nil, err
+	}
+
+	return output, nil
+}